Linkage assembly for connecting a work implement to a frame of a work machine

Information

  • Patent Grant
  • 6409459
  • Patent Number
    6,409,459
  • Date Filed
    Friday, January 30, 1998
    26 years ago
  • Date Issued
    Tuesday, June 25, 2002
    22 years ago
Abstract
A linkage assembly for connecting an implement to a frame of a work machine which provides greater visibility for an operator of the work machine is disclosed. The linkage assembly includes a box-boom lift arm having a frame end portion and an implement end portion, wherein (i) the frame end portion is pivotally coupled to the frame, (ii) the implement end portion is pivotally coupled to the implement, and (iii) the frame end portion includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween. The linkage assembly also includes a lift cylinder having a frame end and a lift arm end, wherein (i) the frame end is pivotally coupled to the frame, and (ii) the lift arm end is pivotally coupled to the box boom lift arm. Moreover, the linkage assembly includes a rear tilt link having a first end and a second end, wherein the first end is pivotally coupled to the frame. The linkage assembly further includes a-rear tilt lever having a cylinder end and a link end, wherein (i) the link end is pivotally coupled to the second end of the rear tilt link, (ii) the rear tilt lever is pivotally coupled to the box boom lift arm at a location which is interposed between the cylinder end and the link end, and (iii) the rear tilt lever extends through the first lever space. The linkage assembly also includes a tilt cylinder having a lever end and an implement end, wherein (i) the lever end is pivotally coupled to the cylinder end of the rear tilt lever, and (ii) the implement end is mechanically coupled to the implement.
Description




TECHNICAL FIELD OF THE INVENTION




The present invention relates generally to a linkage assembly, and more particularly to a linkage assembly for connecting a work implement to a frame of a work machine.




BACKGROUND OF THE INVENTION




Work machines, such as wheel loaders, typically include a linkage assembly which mechanically connects a work implement (e.g. a bucket) to a front end frame (herein after referred to as the “frame”). The linkage assembly will typically include a slab lift arm or a box boom lift arm having one end thereof connected to the frame and the opposite end thereof coupled to the work implement. Generally, the linkage assembly also includes a number mechanical linkages and hydraulic cylinders coupled to the frame and the lift arm such that the lift arm, and therefore the work implement, can be moved relative to the frame. Movement of the lift arm and the work implement relative to the frame is necessary in order to do useful work with the work implement.




During operation of the work machine, the linkage assembly is subjected to various loads and forces, some of which may be severe. Therefore, it is critical that each component thereof has sufficient structure and connection to one another to provide the strength necessary to withstand these loads and forces. Heretofore, linkage assemblies have been constructed to be relatively large and bulky in order to accommodate the aforementioned forces. However, a drawback to these linkage assemblies is that they are so large and bulky that they tend to obstruct the view of an operator operating the work machine.




In addition, it should be understood that, on occasion, it is desirable to maintain the work implement at a predetermined angle relative to the ground while moving the lift arm to a raised position. Typically, linkage assemblies include additional mechanical and/or hydraulic mechanisms to maintain the work implement at the previously mentioned predetermined angle. However, a drawback to adding these additional mechanisms is that they increase the mechanical complexity, the expense, and the bulk of the linkage assembly.




What is needed therefore is a linkage assembly for connecting an implement to a frame of a work machine which overcomes one or more of the above-mentioned drawbacks.




DISCLOSURE OF THE INVENTION




In accordance with a first embodiment of the present invention, there is provided a linkage assembly for connecting an implement to a frame of a work machine. The linkage assembly includes a box-boom lift arm having a frame end portion and an implement end portion, wherein (i) the frame end portion is pivotally coupled to the frame, (ii) the implement end portion is pivotally coupled to the implement, and (iii) the frame end portion includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween. The linkage assembly also-includes a lift cylinder having a frame end and a lift arm end, wherein (i) the frame end is pivotally coupled to the frame, and (ii) the lift arm end is pivotally coupled to the box boom lift arm. Moreover, the linkage assembly includes a rear tilt link having a first end and a second end, wherein the first end is pivotally coupled to the frame. The linkage assembly further includes a rear tilt lever having a cylinder end and a link end, wherein (i) the link end is pivotally coupled to the second end of the rear tilt link, (ii) the rear tilt lever is pivotally coupled to the box boom lift arm at a location which is interposed between the cylinder end and the link end, and (iii) the rear tilt lever extends through the first lever space. The linkage assembly also includes a tilt cylinder having a lever end and an implement end, wherein (i) the lever end is pivotally coupled to the cylinder end of the rear tilt lever, and (ii) the implement end is mechanically coupled to the implement.




In accordance with a second embodiment of the present invention, there is provided a linkage assembly for connecting an implement to a frame of a machine. The linkage assembly includes a lift arm having a frame end portion and an implement end portion, wherein (i) the frame end portion is pivotally coupled to the frame, (ii) the implement end portion is pivotally coupled to the implement, (iii) the lift arm includes an upper arm segment and a lower arm segment, and (iv) the upper arm segment includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween. The linkage assembly also includes a lift cylinder having a frame end and a lift arm end, wherein (i) the frame end is pivotally coupled to the frame, and (ii) the lift arm end is pivotally coupled to the lift arm. Moreover, the linkage assembly includes a rear tilt lever having a cylinder end and a link end, wherein (i) the link end is mechanically coupled to the frame, (ii) the rear tilt lever is pivotally coupled to the lift arm at a location which is interposed between the cylinder end and the link end, and (iii) the rear tilt lever extends through the first lever space. The linkage assembly further includes a tilt cylinder having a lever end and an implement end, wherein (i) the lever end is pivotally coupled to the cylinder end of the rear tilt lever, and (ii) the implement end is mechanically coupled to the implement.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a work machine which incorporates the features of the present invention therein;





FIG. 2

is a perspective view of the frame of the work machine of

FIG. 1

;





FIG. 3

is a front elevational view of the frame of

FIG. 2

;





FIG. 4

is a right side elevational view of the frame of

FIG. 2

;





FIG. 5

is a left side elevational view of the frame of

FIG. 2

;





FIG. 6

is a rear elevational view of the frame of

FIG. 2

;





FIG. 7

is a perspective view of the lift arm assembly and a portion of the linkage assembly of the work machine of

FIG. 1

;





FIG. 8

is another perspective view of the lift arm assembly and the portion of the linkage assembly of the work machine of

FIG. 1

;





FIG. 9

is an enlarged cross sectional view of the left proximal extension of the lift arm assembly taken along the line


9





9


of

FIG. 7

as viewed in the direction of the arrows;





FIG. 10

is a flow chart illustrating a procedure for manufacturing the lift arm assembly of the work machine of

FIG. 1

;





FIG. 11

is a perspective view of the proximal lift arm segment of the lift arm assembly of FIG.


7


and two distal lift arm segments either one of which can be secured to the proximal lift arm segment (distal lift arm segment


130


is shown assembled to proximal lift arm segment


128


in

FIG. 7

while distal lift arm segment


218




10


o is shown assembled to proximal lift arm segment


128


in FIG.


12


);





FIG. 12

is perspective view of an alternative lift arm assembly which can be utilized with the work machine of

FIG. 1

;





FIG. 13

is a perspective view of the frame, the lift arm assembly, the linkage assembly, and the work implement of the work machine of

FIG. 1

(note that the lift arm assembly is shown in a partially raised position and only a fragmentary view of the work implement is shown for clarity of description);





FIG. 14

is a schematic side elevational view of the frame, the lift arm assembly, the linkage assembly, the coupler, and the work implement of the work machine, with the lift arm assembly shown in a lowered position;





FIG. 15

is a view similar to the one shown in

FIG. 14

, but showing the lift arm assembly in a raised position;





FIG. 16

is a view similar to the one shown in

FIG. 15

, but showing the work implement and the coupler in a dumping position (note that a wheel is shown for clarity of description);





FIG. 17

is a view similar to

FIG. 16

, but showing a second configuration of the lift arm assembly;





FIG. 18

is a view similar to

FIG. 16

, but showing the lift arm assembly positioned at its point of maximum instability;





FIG. 19

is a view similar to

FIG. 17

, but showing the second configuration of the lift arm assembly positioned at its point of maximum instability;





FIG. 20

is a side elevational view of the lift arm assembly of

FIG. 7

;





FIG. 21

is a view of the front portion of the work machine of

FIG. 1

as viewed by an operator positioned in the cab assembly;





FIG. 22

is a view of a front portion of a prior art work machine as viewed by an operator positioned in a cab assembly thereof;





FIG. 23

is a perspective view of the implement coupler and the work implement of the work machine of

FIG. 1

; and





FIG. 24

is an exploded view of the implement coupler and the work implement shown in FIG.


23


.











BEST MODE FOR CARRYING OUT THE INVENTION




While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.




Referring now to

FIG. 1

, there is shown a work machine


10


which incorporates the features of the present invention therein. Work machine


10


includes a rear portion


11


and a front portion


15


. Rear portion


11


includes a cab assembly


12


, a rear end frame


13


, a hitch (not shown), an engine (not shown), a rear axle housing (not shown) and drive train components (not shown). Cab assembly


12


, the hitch, the engine, the rear axle housing, and the drive train components are all mounted to rear end frame


13


. Front portion


15


includes a front end frame


16


(hereinafter called frame


16


), a front axle housing


17


, a work implement


18


, a lift arm assembly


20


, and a linkage assembly


22


.




The Frame of the Work Machine




As shown in

FIG. 2

, frame


16


includes a side wall portion


26


, a side wall portion


32


, a central wall portion


40


, a hitch structure


48


, a box support structure


50


, a box support structure


88


, a floor plate


70


, and an axle mounting structure


46


. Side wall portion


26


has a bore hole


28


, a access hole


30


, and a bore hole


66


defined therein. Side wall portion


32


has a bore hole


34


, a access hole


36


, and a bore hole


68


defined therein. Central wall portion


40


has a bore hole


42


and a bore hole


44


defined therein.




Referring now to

FIGS. 2 and 4

, hitch structure


48


includes an upper plate


58


and a lower plate


60


. Upper plate


58


has a hitch pin aperture


62


defined therein. Upper plate


58


also has a pair of steering cylinder apertures


84


defined therein (one steering cylinder aperture is shown in FIG.


2


). Lower plate


60


has a hitch pin aperture


64


defined therein.




As shown in

FIGS. 3

, and


6


, box support structure


50


includes a front box wall


52


and a back box wall


54


. Box support structure


88


includes a front box wall


90


and a back box wall


92


.




As shown in

FIGS. 2

,


3


,


4


, and


5


, floor plate


70


includes a component hole


72


and a component hole


74


. Side wall portion


32


is welded to an edge


82


(see

FIG. 5

) of floor plate


70


such that a perimeter


78


of component hole


74


is defined by floor plate


70


and side wall portion


32


. Side wall portion


26


is welded to an edge


80


(see

FIG. 4

) of floor plate


70


such that a perimeter


76


(see

FIG. 3

) of component hole


72


is defined by floor plate


70


and side wall portion


26


. Moreover, side wall portion


26


and side wall portion


32


are welded to floor plate


70


in the above described manner such that side wall portion


32


is spaced apart from side wall portion


26


so as to define an interior space


38


therebetween.




In addition, as shown in

FIG. 2

, side wall portion


26


and side wall portion


32


are positioned relative to one another such that (i) bore hole


28


is linearly aligned with bore hole


34


as illustrated by line L


1


and (ii) access hole


30


is linearly aligned with access hole


36


as illustrated by line L


2


.




Referring now to

FIGS. 4 and 5

, upper plate


58


and lower plate


60


of hitch structure


48


are welded to side wall portion


26


and side wall portion


32


so that (i) upper plate


58


and lower plate


60


are vertically spaced apart from each other and (ii) bore hole


66


of side wall portion


26


and bore hole


68


of side wall portion


32


are both positioned below upper plate


58


. In addition, upper plate


58


and lower plate


60


are positioned relative to one another such that hitch pin aperture


62


is linearly aligned with hitch pin aperture


64


as illustrated by Line L


3


. Furthermore, as shown in

FIG. 4

, an end portion


124


of floor plate


70


is welded to an under portion


126


of upper plate


58


.




Referring again to

FIGS. 2 and 3

, central wall portion


40


is positioned within interior space


38


, and a lower section


86


(see

FIG. 3

) thereof is welded to upper plate


58


of hitch structure


48


. Central wall portion


40


is also positioned within interior space


38


such that (i) bore hole


42


is linearly aligned with bore holes


28


and


34


as illustrated by line L


1


and (ii) bore hole


44


is linearly aligned with access holes


30


and


36


as illustrated by line L


2


.




As shown in

FIG. 2

, arranging side wall portion


26


, side wall portion


32


, and central wall portion


40


in the above described manner positions side wall portion


26


in a plane P


1


, side wall portion


32


in a plane P


2


, and central wall portion


40


in a plane P


3


. Planes P


1


, P


2


, and P


3


are vertically oriented and substantially parallel to each other.




Referring now to

FIGS. 3

,


4


, and


6


, back box wall


54


includes a lateral edge


102


, a lateral edge


104


, and a bottom edge


106


. Back box wall


54


is positioned within interior space


38


and interposed between side wall portion


26


and central wall portion


40


. Lateral edge


102


is welded to side wall portion


26


. Lateral edge


104


is welded to central wall portion


40


. Bottom edge


106


is welded to upper plate


58


of hitch structure


48


.




Front box wall


52


includes a lateral edge


94


, a lateral edge


96


, a top edge


98


, and a bottom edge


100


. Front box wall


52


is positioned within interior space


38


and interposed between side wall portion


26


and central wall portion


40


. Lateral edge


94


is welded to side wall portion


26


. Lateral edge


96


is welded to central wall portion


40


. Bottom edge


100


is welded to upper plate


58


of hitch structure


48


, and top edge


98


is welded to back box wall


54


. Positioning front box wall


52


and back box wall


54


in the above described manner locates box support structure


50


in interior space


38


and results in side wall portion


26


, central wall portion


40


, front box wall


52


, back box wall


54


, and upper plate


58


of hitch structure


48


defining a sealed void


56


(see FIG.


4


).




Referring now to

FIGS. 3

,


5


, and


6


, back box wall


92


includes a lateral edge


108


, a lateral edge


110


, and a bottom edge


112


. Back box wall


92


is positioned within interior space


38


and interposed between side wall portion


32


and central wall portion


40


. Lateral edge


108


is welded to side wall portion


32


. Lateral edge


110


is welded to central wall portion


40


. Bottom edge


112


is welded to upper plate


58


of hitch structure


48


.




Front box wall


90


includes a lateral edge


114


, a lateral edge


116


, a top edge


118


, and a bottom edge


120


. Front box wall


90


is positioned within interior space


38


and interposed between side wall portion


32


and central wall portion


40


. Lateral edge


114


is welded to side wall portion


32


. Lateral edge


116


is welded to central wall portion


40


. Bottom edge


120


is welded to upper plate


58


of hitch structure


48


, and top edge


118


is welded to back box wall


92


. Positioning front box wall


90


and back box wall


92


in the above described manner locates box support structure


88


in interior space


38


and results in side wall portion


32


, central wall portion


40


, front box wall


90


, back box wall


92


, and upper plate


58


of hitch structure


48


defining a sealed void


122


.




Referring again to

FIG. 2

, axle mounting structure


46


is welded to side wall portion


26


and side wall portion


32


such that axle mounting structure


46


is free from contact with central wall portion


40


.




Frame


16


is secured to front axle housing


17


(see

FIG. 1

) via axle mounting structure


46


in a well known manner. For example, such securement can be achieved by utilizing bolts inserted through apertures defined in axle mounting structure


46


and into apertures defined in axle housing


17


to secure frame


16


to axle housing


17


. Front portion


15


(see

FIG. 1

) is then mechanically coupled to rear portion


11


(see

FIG. 1

) via hitch structure


48


of frame


16


in a well known manner such that work machine


10


can be steered by rotating front portion


15


relative to rear portion


11


.




It should be understood that frame


16


is relatively compact as compared to existing front end frames. The compactness of frame


16


provides an operator with a relatively unobstructed view of a work area seen from cab assembly


12


as shown in

FIG. 21

as compared to existing frames (e.g. see FIG.


22


).




However, even though frame


16


is relatively small and compact, it is still configured to possess the structural strength required to accommodate high loads generated during the use of work implement


18


. One reason frame


16


can accommodate these high loads is that its structure is designed to efficiently transfer loads from work implement


18


through lift arm assembly


20


, side wall portion


26


, side wall portion


32


, and central wall portion


40


to front axle housing


17


(via axle mounting structure


46


) and rear end frame


13


(via hitch structure


48


).




The Lift Arm Assembly of the Work Machine




Referring now to

FIGS. 7 and 8

, lift arm assembly


20


includes a proximal lift arm segment


128


and a distal lift arm segment


130


. The lift arm assembly also includes a frame end portion


246


defined by proximal lift arm segment


128


, and an implement end portion


248


defined by the distal lift arm segment


130


. Lift arm assembly


20


also includes a left proximal extension


174


, a right proximal extension


176


, a left distal extension


178


, and a right distal extension


180


(as viewed by a bystander in the general direction of arrow


475


). In addition, lift arm assembly


20


includes a left frame coupling


136


having a left frame pin bore


138


defined therein, a right frame coupling


190


having a right frame pin bore


192


defined therein, a left implement coupling


140


having a left implement pin bore


142


defined therein, and a right implement coupling


194


having a right implement pin bore


308


defined therein. Furthermore, lift arm assembly


20


includes a linkage pin bore


132


, a linkage pin bore


133


(see FIG.


11


), a linkage pin bore


134


, a linkage pin bore


135


(see FIG.


11


), a cylinder pin bore


186


, and a slot


172


(see FIG.


8


).




Proximal lift arm segment


128


has left proximal extension


174


and right proximal extension


176


extending therefrom. Left proximal extension


174


and right proximal extension


176


are spaced apart from each other so as to define a lever space


292


therebetween. Left proximal extension


174


also has linkage pin bore


132


and cylinder pin bore


186


defined therein. Right proximal extension


176


has linkage pin bore


133


(see

FIG. 11

) defined therein. A cylinder pin bore (not shown) is also formed in right proximal extension


176


which is substantially identical to cylinder pin bore


186


. Left frame coupling


136


is secured to an end of left proximal extension


174


. Right frame coupling


190


is secured to an end of right proximal extension


176


.




Distal lift arm segment


130


has left distal extension


178


and right distal extension


180


extending therefrom. Left distal extension


178


and right distal extension


180


are spaced apart from each other so as to define a link space


294


therebetween. Left distal extension


178


also has linkage pin bore


134


defined therein. Right distal extension


180


also has a linkage pin. bore


135


(see

FIG. 11

) defined therein. Left implement coupling


140


is secured to an end of left distal extension


178


. Right implement coupling


194


is secured to an end of right distal extension


180


.




Structurally, lift arm assembly


20


is a “box boom lift arm”. What is meant herein by a “box boom lift arm” is a lift arm assembly fabricated from a number of metal plates such that the lift arm assembly has (i) a generally hollow interior and (ii) the structure of the lift arm assembly has a generally rectangular shaped transverse cross section which extends for a substantial distance along the length of the lift arm assembly as shown in

FIGS. 7 and 8

.




An advantage of utilizing a “box boom lift arm” is that they are typically stiffer and stronger than a lift arm assembly of substantially equal weight which utilize a different structural design. For example, a lift arm assembly which utilizes a “box boom lift arm” structural design will typically be stiffer and stronger than a lift arm assembly of substantially equal weight which utilizes a “slab type” structural design.




As shown in

FIG. 9

, left proximal extension


174


generally illustrates the structural characteristics of a “box boom lift arm”. Specifically, left proximal extension


174


includes a side plate


146


, a side plate


148


, an under plate


160


, an intermediate plate


166


, and an over plate


158


.




A bottom edge


162


of side plate


146


is secured to under plate


160


such that side plate


146


extends upwardly from under plate


160


. In a similar manner, a bottom edge


164


of side plate


148


is secured to under plate


160


such that side plate


148


extends upwardly from under plate


160


. Over plate


158


is secured to a top edge


154


of side plate


146


. Over plate


158


is also secured to a top edge


156


of side plate


148


. Over plate


158


is secured to side plate


146


and side plate


148


such that over plate


158


is in a substantially parallel relationship with under plate


160


. Intermediate plate


166


is interposed between and secured to both side plate


146


and side plate


148


such that intermediate plate


166


is positioned in a substantially parallel relationship with over plate


158


and under plate


160


. Arranging and securing side plate


146


, side plate


148


, over plate


158


, and under plate


160


in the above described manner results in left proximal extension


174


having a generally hollow interior


144


and a generally rectangular shaped transverse cross section.




It should be understood that proximal lift arm segment


128


, including right proximal extension


176


, has structural characteristics similar to those described for left proximal extension


174


. Moreover, distal lift arm segment


130


, including left distal extension


178


and right distal extension


180


, has structural characteristics similar to those described above for left proximal extension


174


. As a result, lift arm assembly


20


is a has (i) a generally hollow interior and (ii) the structure of lift arm assembly


20


has a generally rectangular shaped transverse cross section which extends substantially along the entire length of lift arm assembly


20


.




Referring now to

FIGS. 10 and 11

, a procedure


203


is used to manufacture lift arm assembly


20


(see FIG.


7


). Procedure


203


begins with a step


204


in which proximal lift arm segment


128


and distal lift arm segment


130


are formed. It should be understood that proximal lift arm segment


128


and distal lift arm segment


130


are formed as two independent, separate, subassemblies of lift arm assembly


20


(see FIG.


7


). In particular, proximal lift arm segment


128


is formed as described above in reference to

FIGS. 7

,


8


, and


9


so as to include left proximal extension


174


and right proximal extension


176


. In addition, proximal lift arm segment


128


is fabricated to include welding edges


300


(see FIG.


11


).




Distal lift arm segment


130


is formed to include left distal extension


178


and right distal extension


180


. In addition, distal lift arm segment


130


is formed to include welding edges


302


.




It should be appreciated that the order in which proximal lift arm segment


128


and distal lift arm segment


130


are formed is not important to the present invention. That is, proximal lift arm segment


128


can be formed before, after, or simultaneously with, distal lift arm segment


130


.




In addition, step


204


includes welding the couplings to proximal lift arm segment


128


and distal lift arm segment


130


. Specifically, left frame coupling


136


is welded to left proximal extension


174


and right frame coupling


190


is welded to right proximal extension


176


during the formation of proximal lift arm segment


128


. In a similar manner, left implement coupling


140


is welded to left distal extension


178


and right implement coupling


194


is welded to right distal extension


180


during the formation of distal lift arm segment


130


. It should be appreciated that the order in which the couplings are welded is not important to the present invention.




After completion of step


204


, the next step in procedure


203


is step


206


. In step


206


, linkage pin bore


132


, linkage pin bore


133


(see FIG.


11


), cylinder pin bore


186


, and the cylinder pin bore defined in right proximal extension


176


(not shown) are formed in proximal lift arm segment


128


. In addition, linkage pin bore


134


and linkage pin bore


135


(see

FIG. 11

) are formed in distal lift arm segment


130


. In particular, a machining complex (not shown) is preferably used to form linkage pin bore


132


and cylinder pin bore


186


in left proximal extension


174


of proximal lift arm segment


128


. The machining complex is also used to form linkage pin bore


133


and the cylinder pin bore (not shown) defined in right proximal extension


176


.




The machining complex is also utilized to form linkage pin bore


134


in left distal extension


178


of distal lift arm segment


130


and linkage pin bore


135


in right distal extension


180


. In addition, it should be understood that the machining complex can be used to form pin bores


138


,


142


,


192


, and


308


(see FIG.


8


).




After completion of step


206


, the next step in procedure


203


is step


208


. In step


208


, proximal lift arm segment


128


is welded to distal lift arm segment


130


. In particular, proximal lift arm segment


128


is positioned relative to distal lift arm segment


130


such that welding edges


300


(see

FIG. 11

) of proximal lift arm segment


128


and welding edges


302


(see

FIG. 11

) of distal lift arm segment


130


are in contact. It should be understood that the above described “bores” formed in step


206


are used as locators in conjunction with a number of pins (not shown) and a fixture apparatus (not shown) to position proximal lift arm segment


128


relative to distal lift arm segment


130


such that welding edges


300


and welding edges


302


are in contact. Welding edges


300


and


302


are then welded together to form a weld seam


304


(see

FIGS. 7 and 8

) that secures proximal lift arm segment


128


to distal lift arm segment


130


as shown in

FIGS. 7 and 8

.




Hereinafter, linkage pin bore


132


, linkage pin bore


133


, cylinder pin bore


186


, linkage pin bore


134


, linkage pin bore


135


, and the cylinder pin bore formed in right proximal extension


176


are collectively referred to as the “pin bores”. It should be appreciated that performing step


206


(i.e. forming the pin bores in proximal lift arm segment


128


and distal lift arm segment


130


) of procedure


203


prior to performing step


210


(i.e. welding proximal lift arm segment


128


to distal lift arm segment


130


) is an important aspect of the present invention which provides several advantages.




Specifically, proximal lift arm segment


128


is relatively small as compared to lift arm assembly


20


. Similarly, distal lift arm segment


130


is relatively small as compared to lift arm assembly


20


. In particular proximal lift arm segment


128


has a shorter length L


8


(see

FIG. 11

) as compared to the length L


7


(see

FIG. 7

) of lift arm assembly


20


, and distal lift arm segment


130


also has a shorter length L


4


(see

FIG. 11

) as compared to the length L


7


(see

FIG. 7

) of lift arm assembly


20


. The size of the machining complex required to form the pin bores (i.e. step


206


) in a structure, such as lift arm assembly


20


or proximal lift arm segment


128


, is directly proportional to the size of the structure. For example, since lift arm assembly


20


is larger (e.g. longer) than proximal lift arm segment


128


, a larger machining complex would be required to form the pin bores in lift arm assembly


20


as compared to forming them in proximal lift arm segment


128


.




It should be appreciated that larger machining complexes are significantly more expensive than smaller machining complexes. Thus utilizing a larger machining complex increases the manufacturing cost of lift arm assembly


20


. The present invention results in a decrease in manufacturing costs by first forming the pin bores in proximal lift arm segment


128


and distal lift arm segment


130


with a relatively small machining complex, and then welding proximal lift arm segment


128


and distal lift arm segment


130


together to form the relatively large (i.e. longer) lift arm assembly


20


structure.




After completion of procedure


203


, lift arm assembly


20


is secured to frame


16


of work machine


10


(see FIGS.


1


and


13


). Specifically, as shown in

FIG. 13

, frame end portion


246


of lift arm assembly


20


is positioned relative to frame


16


(see

FIG. 2

) such that (i) left frame coupling


136


(see

FIG. 7

) is interposed between side wall portion


26


and central wall portion


40


of frame


16


and (ii) right frame coupling


190


(see

FIG. 8

) is interposed between central wall portion


40


and side wall portion


32


of frame


16


. Lift arm assembly


20


is further positioned in the above described manner such that left frame pin bore


138


(see

FIG. 7

) of left frame coupling


136


(see

FIG. 7

) and right frame pin bore


192


(see

FIG. 8

) of right frame coupling


190


(see

FIG. 8

) are linearly aligned with bore hole


28


(see FIG.


2


), bore hole


42


(see FIG.


2


), and bore hole


34


(see

FIG. 2

) of frame


16


. A frame pin


260


is then advanced through bore hole


28


, bore hole


42


, bore hole


34


, left frame pin bore


138


(see FIG.


8


), and right frame pin bore


192


(see

FIG. 8

) so as to pivotally couple left proximal extension


174


and right proximal extension


176


(and thus lift arm assembly


20


) to frame


16


at a frame area


296


.




As will be discussed in greater detail below lift arm assembly


20


is designed for certain work applications. For example, lift arm assembly


20


is preferably used to lift loads having a relatively low density, such as agricultural products. However, as shown in

FIGS. 11 and 12

, other lift arm assembly configurations can be manufactured utilizing procedure


203


. Specifically, an alternative distal lift arm segment


218


can be substituted for distal lift arm segment


130


in step


210


of procedure


203


. As a result, distal lift arm segment


218


is welded to proximal lift arm segment


128


rather than distal lift arm segment


130


. Welding distal lift arm segment


218


to proximal lift arm segment


128


produces an alternative lift arm assembly


214


as shown in FIG.


12


.




It should be appreciated that alternative lift arm assembly


214


is pivotally coupled to frame


16


in the same manner as described above for lift arm assembly


20


since lift arm assembly


214


and lift arm assembly


20


have substantially identical proximal lift arm segments (i.e. proximal lift arm segment


128


). However, one difference between distal lift arm segment


130


and distal lift arm segment


218


is that distal lift arm segment


130


has a length L


4


(see

FIG. 11

) and distal lift arm segment


218


has a length L


5


. Length L


4


is greater than L


5


. Since the length of proximal lift arm segment


128


remains constant, welding distal lift arm segment


218


to proximal lift arm segment


128


results in lift arm assembly


214


having a length L


6


(see

FIG. 12

) which is less than the length L


7


(see

FIG. 7

) of lift arm assembly


20


. The shorter length L


6


of lift arm assembly


214


results in lift arm assembly


214


being better suited for lifting relatively high density loads, such as earth or rock, as compared to lift arm assembly


20


.




It should be appreciated that keeping the physical configuration of proximal lift arm segment


128


constant while providing a number of alternative distal lift arm segment configurations (e.g. distal lift arm segments


130


and


218


) for welding to proximal lift arm segment


128


is another advantage of the present invention. Specifically, keeping the physical configuration of proximal lift arm segment


128


constant while providing several alternative distal lift arm segment configurations provides an economical method to produce and utilize lift arm assemblies designed for a wide range of applications. For example, having a standardized configuration of proximal lift arm segment


128


ensures that different lift arm assembly configurations, such as lift arm assemblies


20


and


214


, can be utilized on work machine


10


with out altering frame


16


. This is true since frame


16


is designed to cooperate with proximal lift arm segment


128


, and the physical characteristics thereof remain constant (e.g. location of the pin bores). Thus, work machine


10


can be equipped with lift arm assembly


20


or alternative lift arm assembly


214


without altering frame


16


. Being able to utilize any one of several lift arm assembly configurations (e.g. lift arm assembly


20


or lift arm assembly


214


) without altering frame


16


enhances the versatility of work machine


10


.




As discussed above, utilizing procedure


203


to manufacture a “box boom lift arm” type lift arm assembly (i.e. lift arm assembly


20


) has several advantages. However, it should be understood that procedure


203


can also be utilized to manufacture other types of lift arm assemblies, such as “slab type” lift arm assemblies.




The Linkage Assembly of the Work Machine




Referring now to

FIGS. 7

,


8


, and


13


, linkage assembly


22


includes lift arm assembly


20


, a lift cylinder


250


, a lift cylinder


328


, a rear tilt link


256


, a rear tilt lever


262


, and a tilt cylinder


270


. Linkage assembly


22


also includes a front tilt lever


276


, a front tilt link


282


, and an implement coupler


290


.




Referring now to

FIGS. 13 and 14

, lift cylinder


250


has a frame end


252


and a lift arm end


254


. Lift cylinder


250


is positioned relative to frame


16


such that frame end


252


is located within interior space


38


of frame


16


and positioned adjacent to bore hole


66


(see

FIG. 2

) of side wall portion


26


. Lift cylinder


250


is also positioned relative to frame


16


such that lift cylinder


250


extends through component hole


72


of floor plate


70


(see FIG.


3


). A pin


310


is then inserted through bore hole


66


and frame end


252


so as to pivotally couple lift cylinder


250


to frame


16


.




Lift cylinder


250


is also positioned relative to lift arm assembly


20


such that lift arm end


254


is inserted up through slot


172


(see

FIG. 8

) of lift arm assembly


20


and located adjacent to cylinder pin bore


186


(see FIG.


8


). A pin


312


is then inserted through cylinder pin bore


186


and lift arm end


254


so as to pivotally couple lift cylinder


250


to lift arm assembly


20


.




Lift cylinder


328


is pivotally coupled to frame


16


and lift arm assembly


20


in substantially the same manner as that described for lift cylinder


250


. Specifically, lift cylinder


328


has a frame end (not shown) and a lift arm end (not shown). Lift cylinder


328


is positioned relative to frame


16


such that the frame end thereof is located within interior space


38


of frame


16


and positioned adjacent to bore hole


68


(see

FIG. 5

) of side wall portion


32


. Lift cylinder


328


is also positioned relative to frame


16


such that lift cylinder


328


extends through component hole


74


of floor plate


70


. A pin (not shown) is then inserted through bore hole


68


(see

FIG. 5

) and through the frame end of lift cylinder


328


so as to pivotally couple lift cylinder


328


to frame


16


.




Lift cylinder


328


is also positioned relative to lift arm assembly


20


such that the lift arm end (not shown) thereof is inserted up through the slot (not shown) defined in right proximal extension


176


of lift arm assembly


20


and located adjacent to the cylinder pin bore (not shown) formed therein. A pin (not shown) is then inserted through the cylinder pin bore and the lift arm end so as to pivotally couple lift cylinder


328


to lift arm assembly


20


.




Referring again to

FIGS. 7 and 8

, rear tilt lever


262


includes a plate


314


, a plate


316


, and a cross tube member


317


. Plate


314


has a hole


320


and a hole


322


defined therein such that holes


320


and


322


are positioned at opposite ends of plate


314


. Plate


314


also has an aperture


326


(see

FIG. 8

) defined therethrough. Aperture


326


is interposed between hole


320


and hole


322


.




Plate


316


is constructed in a substantially identical manner as plate


314


. Specifically, plate


316


has a hole


324


defined in one end thereof. Plate


316


also has another hole (not shown) defined in the end of plate


316


opposite to the end having hole


324


. Plate


316


also has an aperture (not shown) defined therethrough. The aperture formed in plate


316


is interposed between hole


324


and the other hole (not shown).




Plate


314


and plate


316


are spaced apart from each other in a substantially parallel relationship so that a plate space


318


(see

FIG. 7

) is defined therebetween. Cross tube member


317


is positioned within plate space


318


and secured to plate


314


and plate


316


such that a conduit (not shown) defined by cross tube member


317


is linearly aligned with aperture


326


formed in plate


314


and the aperture formed in plate


316


. Plate


314


and plate


316


are also positioned relative to one another such that holes


320


and


324


are linearly aligned. Plate


314


and plate


316


are further positioned relative to one another such that hole


322


and the hole defined in the end of plate


316


opposite to the one having hole


324


defined therein are linearly aligned.




Rear tilt lever


262


is positioned within lever space


292


such that cross tube member


317


and the apertures formed in plate


314


and plate


316


(i.e. aperture


326


and the one formed in plate


316


(not shown)) are linearly aligned with linkage pin bore


132


formed in left proximal extension


174


and linkage pin bore


133


(see

FIG. 11

) formed in right proximal extension


176


. Rear tilt lever


262


is further positioned within lever space


292


such that rear tilt lever


262


extends through lever space


292


. Positioning rear tilt lever


262


in the above described manner results in a cylinder end


264


and a link end


266


of rear tilt lever


262


extending out of lever space


292


.




As shown in

FIG. 14

, a pin


330


is then inserted through linkage pin bore


132


, cross tube member


317


, the apertures formed in plate


314


and plate


316


(i.e. aperture


326


and the one formed in plate


316


(not shown)), and linkage pin bore


133


(see

FIG. 11

) so as to pivotally couple rear tilt lever


262


to lift arm assembly


20


at a location which is interposed between cylinder end


264


and link end


266


.




Referring to

FIG. 8

, rear tilt link


256


includes a plate


332


, a plate


334


, and a boss


336


. Plate


332


has a hole


338


defined in one end thereof and a hole


344


defined in the opposite end thereof. Plate


334


is constructed in a substantially identical manner as plate


332


. Specifically, plate


334


also has a hole defined in each end thereof, however only a hole


340


is shown. Plate


332


and plate


334


are spaced apart from each other in a substantially parallel relationship so that a plate space


342


is defined therebetween. Boss


336


is positioned within plate space


342


and secured to plate


332


and plate


334


such that a passageway (not shown) defined by boss


336


is linearly aligned with hole


344


in plate


332


and the hole (not shown) defined in plate


334


. Plate


332


and plate


334


are also positioned relative to one another such that holes


338


and


340


are linearly aligned.




Rear tilt link


256


has an end


258


and an end


260


. Rear tilt link


256


is positioned relative to link end


266


of rear tilt lever


262


such that end


260


of rear tilt link


256


is positioned within plate space


318


(see

FIG. 7

) of rear tilt lever


262


. Rear tilt link


256


is further positioned relative to link end


266


of rear tilt lever


262


such that hole


344


in plate


332


, the hole (not shown) defined in plate


334


, the passageway (not shown) defined by boss


336


, and the holes (i.e. hole


322


and the hole formed in plate


316


(not shown)) defined in rear tilt lever


262


are linearly aligned.




As shown in

FIGS. 13 and 14

, a pin


346


is then inserted through hole


344


in plate


332


(see FIG.


8


), the hole (not shown) defined in plate


334


, the passageway (not shown) defined by boss


336


, and the holes (i.e. hole


322


and the hole formed in plate


316


(not shown)) defined in rear tilt lever


262


so as to pivotally couple rear tilt link


256


to link end


266


of rear tilt lever


262


.




End


258


of rear tilt link


256


is positioned relative to frame


16


such that central wall portion


40


of frame


16


is interposed between plates


332


and


334


of rear tilt link


256


. End


258


of rear tilt link


256


is further positioned relative to frame


16


such that hole


338


defined in plate


332


(se

FIG. 8

) and hole


340


defined in plate


334


(see

FIG. 8

) are linearly aligned with bore hole


44


defined in central wall portion


40


(see FIG.


2


). A pin


348


is then inserted through access hole


30


of side wall portion


26


(see FIG.


2


), holes


338


and


340


of rear tilt link


256


, bore hole


44


of central wall portion


40


(see FIG.


2


), and access hole


36


of side wall portion


32


(see

FIG. 2

) so as to pivotally couple end


258


of rear tilt link


256


to frame


16


at a frame area


298


which is located vertically below frame area


296


(see FIG.


13


).




Referring back to

FIGS. 7 and 8

, front tilt link


282


has a lever end


284


and a lift arm end


286


. Lever end


284


has a hole


352


defined therein and lift arm end


286


has a hole (not shown) defined therein. Front tilt link


282


is positioned relative to lift arm assembly


20


such that front tilt link


282


extends into link space


294


. Front tilt link


282


is further positioned relative to lift arm assembly


20


such that the hole defined in lift arm end


286


is linearly aligned with linkage pin bore


134


defined in left distal extension


178


(see

FIG. 11

) and with linkage pin bore


135


defined in right distal extension


180


(see FIG.


11


). As shown in

FIGS. 13 and 14

, a pin


350


is inserted through linkage pin bore


134


(see FIG.


11


), the hole (not shown) defined in lift arm end


286


of front tilt link


282


, and linkage pin bore defined


135


(see

FIG. 11

) so as to pivotally couple lift arm end


286


of front tilt link


282


to lift arm assembly


20


.




As shown in

FIGS. 7 and 8

, front tilt lever


276


includes a plate


354


, a plate


356


, a boss


359


, a rear end


278


, and a front end


280


. Plate


354


has a hole


361


in one end and a hole


363


defined in the opposite end thereof. Plate


354


also has an aperture


369


defined therethrough. Aperture


369


formed in plate


354


is interposed between hole


361


and hole


363


. Plate


356


is constructed in a substantially identical manner as that described for plate


354


. Specifically, plate


356


has a hole


365


in one end and a hole (not shown) defined in the opposite end thereof. Plate


356


also has an aperture (not shown) defined therethrough. The aperture (not shown) formed in plate


356


is interposed between hole


365


and the hole not shown. Plate


356


and plate


354


are spaced apart from each other in a substantially parallel relationship so that a plate space


371


is defined therebetween. Boss


359


is positioned within plate space


371


and secured to plate


354


and plate


356


such that a passageway (not shown) defined through boss


359


is linearly aligned with hole


363


and the hole (not shown) formed in the end of plate


356


. Plate


354


and plate


356


are also positioned relative to one another such that holes


361


and


365


are linearly aligned, and aperture


369


and the aperture formed in plate


356


are linearly aligned.




Front tilt lever


276


is positioned relative to front tilt link


282


such that lever end


284


of front tilt link


282


is located within plate space


371


. Front tilt lever


276


is further positioned relative to front tilt link


282


such that aperture


369


formed in plate


354


, hole


352


defined in front tilt link


282


, and the aperture (not shown) defined in plate


356


are linearly aligned. A pin


373


(see

FIG. 14

) is then inserted through aperture


369


, hole


352


, and the aperture (not shown) defined in plate


356


. Pin


373


pivotally couples lever end


284


of front tilt link


282


to front tilt lever


276


at a position


288


which is interposed between rear end


278


and front end


280


of front tilt lever


276


.




Referring now to

FIGS. 13 and 14

, tilt cylinder


270


includes a lever end


272


and an implement end


274


. Tilt cylinder


270


is positioned relative to cylinder end


264


of rear tilt lever


262


such that lever end


272


is located within plate space


318


(see

FIG. 7

) and interposed between holes


320


and


324


. A pin


375


is then inserted through hole


320


(see FIG.


7


), lever end


272


, and hole


324


(see

FIG. 7

) so as to pivotally couple lever end


272


of tilt cylinder


270


to cylinder end


264


of rear tilt lever


262


.




In addition, tilt cylinder


270


is positioned relative to front tilt lever


276


such that implement end


274


is located within plate space


371


and interposed between holes


365


and


361


(see FIG.


7


). A pin


377


is then inserted through hole


365


, implement end


274


, and hole


361


so as to pivotally couple implement end


274


of tilt cylinder


270


to rear end


278


of front tilt lever


276


. It should be understood that coupling tilt cylinder


270


in the above described manner mechanically couples implement end


274


of tilt cylinder


270


to work implement


18


.




It should be appreciated that linkage assembly


22


provides a relatively compact mechanism for mechanically coupling work implement


18


to frame


16


as compared to existing linkage assemblies. The compactness of linkage assembly


22


contributes to providing an operator with a relatively unobstructed view of the work area from cab assembly


12


as shown in

FIG. 21

as compared to existing linkage assemblies (see e.g. FIG.


22


).




In addition, it should be understood that the arrangement of the above described components of linkage assembly


22


allow a greater range of motion of work implement


18


in the directions indicated by arrows


379


and


381


(see

FIG. 14

) as compared to existing linkage assemblies. Being able to rotate work implement


18


to a greater degree as described above improves versatility with alternative work implements. Moreover, the arrangement of the above described components of linkage assembly


22


provide a relatively constant tilt force over the entire range of motion of work implement


18


in the directions indicated by arrows


379


and


381


of FIG.


14


.




Furthermore, as shown in

FIGS. 14 and 15

, tilt cylinder


270


can be extended so as to position work implement


18


such that the intersection of a horizontal line


383


and a linear extension


387


of a surface defined by a floor segment


385


of work implement


18


defines a predetermined angle Θ. It should be appreciated that linkage assembly


22


allows lift arm assembly


20


to be elevated as shown in

FIG. 15

while substantially maintaining work implement


18


at predetermined angle Θ. Maintaining work implement


18


at predetermined angle Θ during lifting thereof helps an operator of work machine


10


reduce dumping of material contained within work implement


18


during an excavation procedure. The ability of linkage assembly


22


to maintain work implement


18


at predetermined angle Θ during lifting thereof is an advantage of the present invention since existing linkage assemblies typically require additional mechanical and/or hydraulic components to maintain the work implement at a predetermined angle relative to a horizontal line (similar to horizontal line


383


) during elevation of the lift arm assembly. These additional components increase the mechanical complexity and expense of these existing linkage assemblies as compared to linkage assembly


22


.




The Implement Coupler of the Work Machine




Referring now to

FIGS. 13

,


23


, and


24


there is shown implement coupler


290


. Implement coupler


290


is operative to connect linkage


22


to work implement


18


. In particular, implement coupler


290


is the interface between linkage


22


and work implement


18


. Furthermore, implement coupler


290


allows work implement


18


to be quickly coupled and decoupled from linkage


22


.




Implement coupler


290


includes a right outside support plate


460


, a right inside support plate


462


, a left inside support plate


464


and a left outside support plate


466


(as viewed by a bystander in the general direction of arrow


475


). A center box section


468


is welded to the lower portions of inside right support plate


462


and left inside right support plate


464


. A rear box section


480


(see

FIG. 13

) is welded to the lower portions of right outside support plate


460


, right inside support plate


462


, left inside support plate


464


, and left outside support plate


466


such that each of the support plates are substantially parallel. Center box section


468


and rear box section


480


provide structure that transfers load from work implement


18


to linkage


22


during lifting operations.




A tube section


470


is welded to the upper portion of right outside support plate


460


, right inside support plate


462


, left inside support plate


464


, and left outside support plate


466


. A right support bar


472


is affixed to right outside support plate


460


and extends outwardly in the general direction of arrow


476


. Similarly, a left support bar


474


is affixed to left outside support plate


466


and extends outwardly in the general direction of arrow


478


.




Right inside support plate


462


has a right tilt pin bore


484


defined therethrough at a point located between tube section


470


and center box section


480


. Left inside support plate


464


has a left tilt pin bore


485


defined therethrough at a point located between tube section


470


and center box section


480


. It should be appreciated that right tilt pin bore


484


and left tilt pin bore


485


are linearly aligned such that a tilt pin


486


can be inserted through right tilt pin bore


484


and left tilt pin bore


485


. Moreover, a tilt pin fastener (not shown) can secure tilt pin


486


to right inside support plate


462


and left inside support plate


464


such that tilt pin


486


is prevented from moving in the general directions of arrows


476


and


478


.




The right outside support plate


460


further has a right outside implement pin bore


492


defined therethrough and right inside support plate


462


further has a right inside implement pin bore


494


defined therethrough at points located near center box section


480


. Similarly, left inside support plate


464


has a right inside tilt pin bore


496


defined therethrough and left outside support plate


466


further has an outside implement pin bore


498


defined therethrough at points located near center box section


468


. It should be appreciated that right outside implement pin bore


492


, right inside implement pin bore


494


, left inside implement pin bore


496


, and left outside implement pin bore


498


are linearly aligned such that an right implement pin


500


can be inserted through right outside implement pin bore


492


, through right inside implement pin bore


494


, and into center box section


468


whereas left implement pin


501


can be inserted through left outside implement pin bore


498


, through left inside implement pin bore


496


, and into center box section


468


. Moreover, a right implement pin fastener (not shown) can secure right implement pin


500


to right outside support plate


460


and right inside support plate


462


such that right implement pin


500


is prevented from moving in the general directions of arrows


476


and


478


. Similarly, a left implement pin fastener (not shown) can secure left implement pin


501


to left outside support plate


466


and left inside support plate


464


such that left implement pin


501


is prevented from moving in the general directions of arrows


476


and


478


.




Positioned within rear box section


480


is a cylinder which is divided into a right half coupler cylinder


481


(shown in phantom) and a left half coupler cylinder


479


(shown in phantom). A left engagement pin


488


is secured to a movable rod (not shown) of left half coupler cylinder


479


. (Alternatively, left engagement pin


488


may simply be an end portion of the movable rod of left half coupler cylinder


479


.) Hydraulic fluid can be advanced into the left half coupler cylinder


479


to move left engagement pin


488


in the general direction of arrow


476


and hydraulic fluid can be advanced into the left half coupler cylinder


479


to move left engagement pin


488


in the general direction of arrow


478


. When the left half coupler cylinder


479


moves left engagement pin


488


in the general direction of arrow


476


, left engagement pin


488


is positioned in a first pin position as shown in FIG.


24


. In the first pin position, left engagement pin


488


does not extend through a left second coupling aperture


490


defined in left outside support plate


466


and is spaced apart from work implement


18


. When the left half coupler cylinder


479


moves left engagement pin in the general direction of arrow


478


, left engagement pin


488


is positioned in a second pin position as shown in FIG.


23


. In the second pin position, left engagement pin


488


extends through second coupling aperture


490


defined in left outside support plate


466


.




In a similar manner, a right engagement pin


487


is secured to a movable rod (not shown) of right half coupler cylinder


481


. (Alternatively, right engagement pin


487


may simply be an end portion of the movable rod of right half coupler cylinder


481


.) Hydraulic fluid can be advanced into right half coupler cylinder


481


to move right engagement pin


487


in the general direction of arrow


478


and hydraulic fluid can be advanced to move right engagement pin


487


in the general direction of arrow


476


. When right half coupler cylinder


481


moves right engagement pin


487


in the general direction of arrow


478


, right engagement pin


487


is positioned in a first pin position (not shown). In the first pin position, right engagement pin


487


does not extend through a right second coupling aperture (not shown) defined in right outside support plate


460


and is spaced apart from work implement


18


. When right half coupler cylinder


481


moves right engagement pin


487


in the general direction of arrow


476


, right engagement pin


487


is positioned in a second pin position shown in FIG.


21


. In the second pin position, right engagement


487


pin extends through the second coupling aperture defined in right outside support plate


460


.




Implement coupler


290


is pivotably coupled to lift arm assembly


20


by right implement pin


500


and left implement pin


501


. In particular, right outside implement pin bore


492


and right inside implement pin bore


494


of implement coupler


290


must be aligned with right implement pin bore


308


of linkage


22


shown in

FIG. 7 and 8

whereas left inside implement pin bore


496


and left outside implement pin bore


498


of implement coupler


290


must be aligned with left implement pin bore


142


of linkage


22


as shown in

FIGS. 7 and 8

. Right implement pin


500


is then inserted through right outside implement pin bore


492


of implement coupler


290


; through right implement pin bore


308


of lift arm assembly


20


; through right inside implement pin bore


494


, and into center box section


468


of the implement coupler


290


. Left implement pin


501


is then inserted through left outside implement pin bore


498


of implement coupler


290


; through left implement pin bore


142


of lift arm assembly


20


; through left inside implement pin bore


496


, and into center box section


468


of the implement coupler


290


.




The right implement pin fastener secures right implement pin


500


to implement coupler


290


such that right implement pin


500


is prevented from moving in the general directions of arrows


476


and


478


whereas the left implement pin fastener secures left implement pin


501


to implement coupler


290


such that left implement pin


501


is prevented from moving in the general directions of arrows


476


and


478


. Thus, implement coupler


290


is pivotably coupled to lift arm assembly


20


such implement coupler


290


is free to rotate relative to lift arm assembly


20


at right implement pin


500


and left implement pin


501


in the general directions of arrows


502


and


504


as shown in FIG.


13


.




Implement coupler


290


is also pivotably coupled to front tilt lever


276


of linkage


22


as shown in FIG.


13


. In particular, hole


363


in plate


354


, boss


359


and hole (not shown) in plate


365


of linkage


22


shown in of

FIG. 7 and 8

are aligned with right tilt pin bore


484


and left tilt pin bore


485


of implement coupler


290


shown in FIG.


24


. Tilt pin


486


is then inserted through right tilt pin bore


484


of implement coupler


290


, through the hole in plate


365


of linkage


22


, through boss


359


of linkage


22


, through hole


363


in plate


354


of linkage


22


, and through left tilt pin bore


485


of implement coupler


290


. The tilt pin fastener secures tilt pin


486


to implement coupler


290


such that tilt pin


486


is prevented from moving in the general directions of arrows


476


and


478


. Thus, implement coupler


290


is pivotably coupled to front tilt lever


276


such implement coupler


290


is free to rotate relative to front tilt lever


276


at tilt pin


468


in the general directions of arrows


502


and


504


as shown in FIG.


13


.




It should be appreciated that implement coupler


290


can be rotated about right implement pin


500


and left implement pin


501


. In particular, when tilt cylinder


270


is extended in the general direction of arrow


506


shown in

FIG. 13

, front tilt lever


276


is urged in the general direction of arrow


506


so as to urge tilt pin


486


of implement coupler


290


in the general direction of arrow


506


. As tilt pin


486


is urged in the general direction of arrow


506


, implement coupler


290


rotates about right implement pin


500


and left implement pin


501


in the general direction of arrow


502


. Generally, implement coupler


290


is rotated in the general direction of arrow


502


when it is desired to dump a load from work implement


18


attached to implement coupler


290


.




Alternately, when tilt cylinder


270


is retracted in the general direction of arrow


508


shown in

FIG. 13

, front tilt lever


276


is urged in the general direction of arrow


508


so as to urge tilt pin


486


of implement coupler


290


in the general direction of arrow


508


. As tilt pin


486


is urged in the general direction of arrow


508


, implement coupler


290


rotates about right implement pin


500


and left implement pin


501


in the general direction of arrow


504


. Generally, implement coupler


290


is rotated in the general direction of arrow


504


when it is desired to scoop up a load with work implement


18


attached to implement coupler


290


.




Referring now to

FIGS. 23 and 24

, work implement


18


includes a right hinge plate


510


and a left hinge plate


512


secured thereto. Right hinge plate


510


includes a right hook portion


514


defined in the upper portion of right hinge plate


510


. Right hook portion


514


is configured to hookingly engage right support bar


472


of implement coupler


290


. Right hinge plate


510


further has a right first coupler aperture


516


defined therein. Right first coupling aperture


516


is configured to receive right engagement pin


487


of implement coupler


290


shown in FIG.


21


.




Similarly, left hinge plate


512


includes a left hook portion


518


defined in the upper portion of left hinge plate


512


. Left hook portion


518


is configured to hookingly engage left support bar


474


of implement coupler


290


. Left hinge plate


512


further has a left first coupler aperture


520


defined therein. Left first coupling aperture


520


is configured to receive left engagement pin


488


of implement coupler


290


.




In order to couple implement coupler


290


to work implement


18


, lift arm assembly


20


is moved toward work implement


18


. Thereafter, left support bar


474


is positioned proximately below left hook portion


518


of left hinge plate


512


whereas right support bar


472


is positioned proximately below right hook portion


514


of left hinge plate


510


.




As implement coupler


290


is raised in the general of direction of arrow


522


, left support bar


474


is moved into contact with left hook portion


518


of left hinge plate


512


so that left hinge plate


512


is hookingly engaged to implement coupler


290


as shown in FIG.


23


. Similarly, as implement coupler


290


is raised in the general of direction of arrow


522


, right support bar


472


is moved into contact with right hook portion


514


of right hinge plate


510


so that right hinge plate


510


is hookingly engaged to implement coupler


290


as shown in FIG.


23


.




When work implement


18


is hookingly engaged to implement coupler


290


, work implement


18


is free to rotate about left support bar


474


and right support bar


472


in the general direction of arrows


526


and


528


as shown in FIG.


23


.




As implement coupler


290


is moved in the general direction of arrow


522


, work implement


18


will rotate in the general direction of arrow


528


so as position implement coupler


290


into an engagement position as shown in FIG.


23


. In the engagement position, left first coupling aperture


520


of left hinge plate


512


is aligned with left second coupling aperture


490


of implement coupler


290


whereas right first coupling aperture


516


of right hinge plate


510


is aligned with right second coupling aperture (not shown) of implement coupler


290


.




In order to securely couple implement coupler


290


to work implement


18


, left engagement pin


488


and right engagement pin


487


of implement coupler


290


must engage work implement


18


. In particular, the left half coupler cylinder


479


moves left engagement pin


488


from the first pin position where left engagement pin


488


is spaced apart from left first coupler aperture


520


, shown in

FIG. 24

, to the second pin position, as shown in

FIG. 23

, in the general direction of arrow


478


. Specifically, left engagement pin


488


is advanced through left second coupling aperture


490


of implement coupler


290


and through left first coupling aperture


520


of work implement


18


so as to prevent rotation of work implement


18


about left support bar


474


in the general directions of arrows


526


and


528


.




Similarly, right half coupler cylinder


481


moves right engagement pin


487


from the first pin position where right engagement pin


487


is spaced apart from right first coupler aperture


516


(not shown) to the second pin position, as shown in

FIG. 21

, in the general direction of arrow


476


. Specifically, right engagement pin


487


is advanced through the right second coupling aperture of implement coupler


290


and through right first coupling aperture


516


of work implement


18


so as to prevent rotation of work implement


18


about right support bar


472


in the general directions of arrows


526


and


528


.




In order to decouple implement coupler


290


from work implement


18


, left engagement pin


488


and right engagement pin


487


of implement coupler


290


must disengage work implement


18


. In particular, left half coupler cylinder


479


moves left engagement pin


488


from the second pin position shown in

FIG. 23

to the first pin position in which left engagement pin


488


is spaced apart from left first coupling aperture


520


shown in FIG.


24


. Similarly, right half coupler cylinder


481


moves right engagement pin


487


from the second pin position shown in

FIG. 21

to the first pin position (not shown) in which right engagement pin


487


is spaced apart from right first coupling aperture


516


. Moreover, left support bar


474


is moved out of contact with left hook portion


518


and right support bar


472


is moved out of contact with left hook portion


514


as shown in FIG.


24


.




Referring now to

FIGS. 21 and 22

, the advantages of implement coupler


290


associated with use of the narrow box type lift arm


20


are illustrated.

FIG. 21

shows the view of an operator seated in a seat


530


located in cab assembly


12


of work machine


10


shown in FIG.


1


. From the seated position, the operator is able to verify that work implement


18


is coupled to implement coupler


290


. Specifically, the operator can verify that right hook portion


514


of right hinge plate


510


is hookingly engaged to right support bar


472


of implement coupler


290


. Furthermore, the operator can see an end portion of right engagement pin


487


extending through right hinge plate


510


of work implement


18


in the general direction of arrow


476


. In addition, the operator can verify that left hook portion


518


of left hinge plate


512


is hookingly engaged to left support bar


474


of implement coupler


290


. Furthermore, the operator can see an end portion of left engagement pin


488


extending through left hinge plate


512


of work implement


18


in the general direction of arrow


478


.





FIG. 22

shows the view of an operator seated in a seat located in cab assembly of an exemplary prior art articulated loader. The lift arm typically consists of a right slab arm


540


and a left slab arm


542


along with supports therebetween which obscure a significant portion of the operator's view to the front of work machine. Note that the operator's view of right hook portion of right hinge plate hookingly engaging right support bar of implement coupler is prevented by portions of the linkage in the general area of


532


. Furthermore, the operator's view of the end portion of the right engagement pin extending through the right hinge plate of the implement is prevented by portions of the linkage in the general area of


533


. Similarly, the operator's view of the left hook portion of the left hinge plate hookingly engaging to the left support bar of the implement coupler is prevented by portions of the linkage in the general area of


534


. Furthermore, the operator's view of the left engagement pin extending through the left hinge plate of the implement is prevented by portions of the linkage in the general area of


535


.




The Extended Lift Arm of the Work Machine




Referring now to

FIGS. 16 through 20

, two different extended configurations of lift arm assembly


20


are shown. The first extended configuration of lift arm assembly


20


shown in

FIGS. 16

,


18


, and


20


is exemplary lift arm assembly


20


of the present invention. Alternately, the second extended configuration of lift arm assembly


20


′ shown in

FIGS. 17 and 19

is similar to alternative lift arm


214


shown in

FIG. 12

but has an extended length. The second extended configuration of lift arm assembly


20


is presented to demonstrate the advantages of the first extended configuration of lift arm assembly


20


.





FIGS. 16 through 20

each show a left side elevational view of lift arm assembly


20


. Lift arm assembly


20


has several components that share common locations when viewed from the left side. For example, left frame pin bore


138


is located at the same position as right frame pin bore


192


(shown in

FIG. 8.

) when viewed from the left side as in

FIGS. 16 through 20

. Therefore, for clarity of description only the components that can directly be viewed from the left side will be discussed. It should be appreciated that the components viewed from the right side of work machine


10


are substantially identical to components viewed from the left side of work machine


10


.




Left frame pin bore


138


has a frame pin axis


400


as a centerline. It should be appreciated that frame pin axis


400


is the axis about which lift arm assembly


20


rotates relative to frame


16


. In particular, frame pin


260


(see also

FIG. 13

) pivotably couples left frame pin bore


138


and right frame pin bore


192


, to pin bores


28


,


42


,


34


of frame


16


, as described above, thereby allowing lift arm assembly


20


to rotate relative to frame


16


in the general direction of arrows


410


and


412


.




In a similar manner, left cylinder pin bore


186


has a cylinder pin axis


402


as a centerline. Cylinder pin axis


402


is the axis about which left lift cylinder


250


rotates when coupled to lift arm assembly


20


. In particular, as lift cylinder


250


is extended, lift arm assembly


20


is urged into an upper position as shown in

FIGS. 16 and 17

. Lift arm assembly


20


is pivotably coupled to lift arm end


254


of left lift cylinder


250


by pin


312


. As lift arm assembly


20


is moved into an upper position, lift arm end


254


of left lift cylinder


250


rotates about cylinder pin axis


402


in the general direction of arrow


412


as the orientation of lift cylinder


250


changes with respect to lift arm assembly


20


. Similarly, when lift cylinder


250


is retracted, lift arm end


254


of left lift cylinder


250


rotates about cylinder pin axis


402


in the general direction of arrow


410


as the orientation of lift cylinder


250


changes with respect to lift arm assembly


20


.




A first line


404


is the line that connects the frame pin axis


400


(defined by left frame pin bore


138


) and cylinder pin axis


402


(defined by left cylinder pin bore


186


).




Left implement pin bore


142


has an implement pin bore axis


408


as a centerline. It should be appreciated that work implement


18


is attached to lift arm assembly


20


at pin bore


142


by implement pin


501


shown in

FIGS. 23 and 24

. It should further be appreciated that work implement


18


rotates about implement pin bore axis


408


as work implement


18


moves in the general directions of arrows


410


and


412


.




A second line


416


is defined by left implement pin bore


142


and left frame pin bore


138


. Second line


416


connects frame pin axis


400


, defined by left frame pin bore


138


and implement pin bore axis


408


defined by left implement pin bore


142


. It should be appreciated that second line


416


lies above first line


404


. It should further be appreciated that first line


404


and second line


416


define a supplemental lift angle


418


of lift arm assembly


20


.




It should be appreciated that the first extended configuration of lift arm assembly


20


has a supplemental lift angle


418


of approximately nine degrees. It should further be appreciated that the second extended configuration of lift arm assembly


20


′ has a supplemental lift angle


418


of approximately two degrees.




The following description applies to the first extended configuration of lift arm assembly


20


which incorporates the features of the present invention therein.




Referring now to

FIG. 20

, a plane


420


is normal to first line


404


and intersects first line


404


at cylinder pin axis


402


. Plane


420


divides lift arm assembly


20


into a frame-side segment


422


that lies to the left of plane


420


and an implement-side segment


424


that lies to the right of the plane


420


as shown in FIG.


20


.




It should be appreciated that left frame pin bore


138


lies in frame-side segment


422


of lift arm assembly


20


whereas left implement pin bore


142


lies in implement-side segment


424


of lift arm assembly


20


. Furthermore, frame-side segment


422


of lift arm assembly


20


is pivotably coupled to frame


16


at left frame pin bore


138


whereas implement-side segment


424


of lift arm assembly


20


is pivotably coupled to work implement


18


at left implement pin bore


408


.




It should further be appreciated that plane


420


bisects left cylinder pin bore


186


into two equal segments whereby a first half of left cylinder pin bore


186


lies in frame-side segment


422


of lift arm assembly


20


, and a second half of cylinder pin bore


186


lies in implement-side segment


424


of lift arm assembly


20


.




First line


404


has a first line segment


428


defined therein. In particular, a point


426


exists where first line


404


intersects the periphery of implement-side segment


422


of lift arm assembly


20


. In addition, a point


427


lies on the distal side of left cylinder pin bore


186


where first line


404


intersects left cylinder pin bore


186


. First line segment


428


is defined as the portion of first line


404


that lies between point


427


and point


426


. Moreover, first line segment


428


is entirely coincident with implement-side segment


424


of lift arm assembly


20


. What is meant herein by the phrase “is entirely coincident with” is that a line segment is entirely coincident with the lift arm assembly


20


when the entire line segment lies within the periphery of the lift arm assembly


20


as depicted in a side elevational view as shown in FIG.


20


.




First line


404


further has a second line segment


436


defined therein. In particular, a point


432


lies on the proximal side of left cylinder pin bore


186


where first line


404


intersects left cylinder pin bore


186


. In addition, a point


434


lies on the distal side of left frame pin bore


138


where first line


404


intersects left frame pin bore


138


. Second line segment


436


is defined as the portion of first line


404


that lies between point


432


and point


434


. Moreover, second line segment


436


is entirely coincident with frame-side segment


422


of lift arm assembly


20


.




First line


404


further has a third line segment


438


defined therein. In particular, third line segment


438


is defined as the portion of first line


404


that lies beyond point


426


which extends in a direction away from implement-side segment


424


of lift arm assembly


20


. Third line segment


438


is entirely not coincident with lift arm assembly


20


. In particular, third line segment


438


is entirely not coincident with either implement-side segment


424


or frame-side segment


422


of lift arm assembly


20


. It should be appreciated that third line segment


436


lies below the lower edge of the periphery of implement-side segment


424


of lift arm assembly


20


as shown in FIG.


20


.




Second line


416


has a fourth line segment


440


defined therein. In particular, a point


442


lies on the distal side of left frame pin bore


138


where second line


416


intersects left frame pin bore


138


. In addition, a point


444


lies on the proximal side of left implement pin bore


142


where second line


416


intersects left implement pin bore


142


. Fourth line segment


440


is defined as the portion of second line


416


that lies between point


442


and point


444


. Moreover, the entirety of fourth line segment


440


is coincident with lift arm assembly


20


.




Referring now to

FIGS. 16 through 19

, a horizontal line


406


extends from pin bore axis


400


parallel to ground


446


. It should be appreciated that first line


404


and horizontal line


406


define a lift angle


414


of lift arm assembly


20


with respect to frame assembly


16


. Lift angle


414


shown in

FIGS. 16 and 17

corresponds to a maximum lift angle of work machine


10


. Lift angle


414


shown in

FIGS. 18 and 19

places second line


416


parallel to ground


446


and coincident with horizontal line


406


.




For a given configuration of frame


16


, lift arm assembly


20


, and lift cylinder


250


there is a maximum value for lift angle


414


as shown in

FIGS. 16 and 17

. The maximum value of lift angle


414


of work machine


10


is approximately forty four degrees. It should be appreciated that this maximum value of lift angle


414


, supplemental angle


418


, and the length of lift arm assembly


20


define two operational heights for work machine


10


. Maximum lift height


454


is the maximum height that work machine


10


can lift implement pin axis


408


for the first extended configuration of lift arm assembly


20


. Maximum lift height


455


is maximum height that work machine


10


can lift implement pin axis


408


for the second extended configuration of lift arm assembly


20


′.




The maximum dump height


450


is the maximum height at which a load can be dumped from work implement


18


of work machine


10


with the first extended configuration of lift arm assembly


20


. Maximum dump height


451


is the maximum height at which a load can be dumped from work implement


18


of work machine


10


with the second extended configuration of lift arm assembly


20


′.




It should be appreciated that for some work implements, such as forks used to move pallets and the like, maximum lift height


454


,


455


is a better measure of operational capability of work machine


10


than maximum dump height


450


,


451


. Alternately, for other work implements, such as buckets used to haul and lift bulk material, maximum dump height


450


,


451


is a better measure of operational capability of work machine


10


than maximum lift height


454


,


455


.





FIGS. 18 and 19

show that both of the arms have similar stability. Stability is a measure of the likelihood that work machine


10


will overturn. As work machine


10


lifts a load from ground


446


to the upper position shown in

FIGS. 16 and 17

, lift arm assembly


20


must pass a point of maximum instability. The point of maximum instability is the point at which work machine


10


is most likely to overturn due to a moment created by the load. At the point of maximum instability, the load carried by lift arm assembly


20


creates the greatest moment about front wheel


430


.




The point of the maximum moment about front wheel


430


occurs when implement pin bore axis


408


is at a maximum distance


433


, as shown in

FIGS. 18 and 19

, to the right of an axle


435


of front wheel


430


. Maximum distance


433


occurs when the sum of lift angle


414


and supplemental angle


418


is equal to zero degrees, e.g. second line


416


is co-linear with horizontal line


406


and second line


416


is parallel to ground


446


.




There are several methods to decrease the maximum moment and increase the stability of work machine


10


. In particular, the weight of the load carried by work implement


18


can be decreased. Decreasing the weight of the load carried by work implement


18


limits the effectiveness of work machine


10


as more loads must be carried in a given work operation. Alternately, counterweights (not shown) can be mounted on the rear of rear end frame


13


, so as to create a moment about axle


435


of wheel


430


that counteracts the moment created by lifting loads. However, the counterweights also have the significant disadvantage of requiring more energy to move work machine


10


. As a further alternative, the length of lift arm assembly


20


can be reduced. Unfortunately, reducing the length of lift arm assembly


20


also reduces maximum lift height


454


and maximum dump height


451


. Each of the methods to decrease the maximum moment and increase the stability of work machine


10


has a disadvantage when applied to an extended lift arm.




When comparing the first extended configuration of lift arm assembly


20


shown in

FIGS. 16 and 18

to the second extended configuration of lift arm assembly


20


′ shown in

FIGS. 17 and 19

, both extended configurations have a similar point of maximum instability since distance


433


is substantially identical in the two configurations (see FIGS.


18


and


19


). This creates the same maximum moment about axle


435


of wheel


430


as lift arm is moved through a lift angle


414


of zero degrees. However, even though both the of the lift arms are configured for similar maximum instability, maximum lift height


454


of the first extended configuration shown in

FIG. 16

is greater than maximum lift height


455


of the second extended configuration shown in FIG.


17


. Similarly, maximum dump height


450


of the first extended configuration shown in

FIG. 16

is greater than maximum dump height


451


of the second extended configuration shown in FIG.


17


. Therefore, the first extended configuration of lift arm assembly


20


(with supplemental lift angle


418


of approximately nine degrees) is superior to the second extended configuration of lift arm assembly


20


′ (with supplemental lift angle


418


of approximately two degrees) since the first extended configuration provides work machine


10


with a greater lift height


454


while possessing a substantially identical amount of instability as found in the second extended configuration of lift arm assembly


20


′.




Furthermore, an alternative first extended configuration (not shown) of lift arm assembly


20


could be configured such that maximum lift height


454


of the alternative first extended configuration is the same as maximum lift height


455


of the second extended configuration. In such a case, maximum dump height


450


of the alternative first extended configuration would be substantially identical to maximum dump height


451


of the second extended configuration. However, in such an alternative extended configuration, the alternative first extended configuration would have a lesser amount of maximum instability, since maximum distance


433


for the alternative first extended configuration would be less than maximum distance


433


of the second extended configuration of lift arm assembly


20


′. Therefore, the alternate first extended configuration of lift arm assembly


20


(with supplemental lift angle


418


of approximately nine degrees) is superior to the second extended configuration of lift arm assembly


20


′ (with a supplemental lift angle


418


of approximately two degrees) because the alternate first extended configuration provides work machine


10


with a maximum lift height


454


equal to maximum lift height


455


of the second extended configuration with a lesser amount of instability than that exhibited by the second extended configuration.




It should be appreciated that supplemental lift angle


418


of approximately nine degrees, along with the limitations of first line segment


428


, second line segment


436


, third line segment


438


, and fourth line segment


440


can be advantageously achieved with the substantially “s” shape of the first extended configuration of lift arm assembly


20


of

FIGS. 16

,


18


and


20


. The “s” shape also allows a nine degree supplemental lift angle to be incorporated into a design that retains some common components with alternative lift arm assembly


214


. Specifically, frame pin bore


138


of the first extended configuration of lift arm assembly


20


is substantially identical in size, shape, and orientation to frame pin bore


138


of the alternative lift arm assembly


214


as shown in FIG.


12


. In addition, implement pin bore


142


of first extended configuration of lift arm


20


is substantially identical in size shape and orientation to implement pin bore


142


of the alternate lift arm assembly


214


. Thus, the “s” shape has the operational advantage of an enhanced maximum lift height


454


and enhanced maximum dump height


450


, as well as an economic advantage of sharing some common interface components with alternative lift arm assembly


214


shown in FIG.


12


.




Industrial Applicability




The operation of work machine


10


typically includes (i) the excavation of material (not shown) from the ground or a pile and (ii) the dumping of the material in a nearby truck (not shown) or the movement thereof to a remote site. Lift arm assembly


20


and work implement


18


are positioned in a lowered position as shown in FIG.


1


. Work implement


18


is then loaded by forcing the material being excavated under the motive force of work machine


10


into the work implement


18


. Work implement


18


is then rotated back toward work machine


10


in a direction indicated by arrow


379


by retracting tilt cylinder


270


as shown in FIG.


14


. Lift arm assembly


20


, and thus work implement


18


, is raised via the extension of lift cylinders


250


and


328


as shown in FIG.


15


. Work implement


18


is then rotated away from work machine


10


in a direction indicated by arrow


381


by the extension of tilt cylinder


270


as shown in

FIG. 16

so as to dump the material contained in work implement


18


at the appropriate location.




In the event that the material contained in work implement


18


is to be dumped into a nearby truck, the bucket is raised to a height above the height of the side wall of the truck. Work machine


10


is then driven toward the truck until work implement


18


extends over the side wall of the truck and over the bed thereof. Tilt cylinder


270


is then extended as shown in

FIG. 16

to rotate work implement


18


away from work machine


10


in the direction indicated by arrow


412


so as to dump the material from work implement


18


into the bed of the truck.




It is well known that the forces applied to frame


16


, lift arm assembly


20


, and linkage arrangement


22


during the above described operation can be extremely severe depending upon the force with which the work machine


10


is driven into the pile of material, the type of material being excavated, and the amount or weight of material lifted and dumped from the work implement


18


. It is imperative that the aforementioned components of work machine


10


possess the size and mass in order to accommodate the most severe loads while still allowing an operator positioned within cab assembly


12


to have a relatively unobstructed view of the work area. Among the other advantages previously discussed, frame


16


, lift arm assembly


20


, linkage assembly


22


, and coupler


290


cooperate to provide the desired strength for excavation and the desired visibility for the operator of the work area as well as key machine components.




While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.



Claims
  • 1. A linkage assembly for connecting an implement to a frame of a work machine, comprising:a box-boom lift arm having a frame end portion and an implement end portion, wherein (i) said frame end portion is pivotally couplable to said frame, (ii) said implement end portion is pivotally couplable to said implement, and (iii) said frame end portion includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween; a lift cylinder having a frame end and a lift arm end, wherein (i) said frame end is pivotally couplable to said frame, and (ii) said lift arm end is pivotally coupled to said box boom lift arm; a rear tilt link having a first end and a second end, wherein said first end is pivotally couplable to said frame; a rear tilt lever having a cylinder end and a link end, wherein (i) said link end is pivotally coupled to said second end of said rear tilt link, (ii) said rear tilt lever is pivotally coupled to said box boom lift arm at a location which is interposed between said cylinder end and said link end, and (iii) said rear tilt lever extends through said first lever space; and a tilt cylinder having a lever end and an implement end, wherein (i) said lever end is pivotally coupled to said cylinder end of said rear tilt lever and (ii) said implement end is mechanically couplable to said implement.
  • 2. The assembly of claim 1, further comprising:a front tilt lever having a rear end and a front end, wherein (i) said rear end is pivotally coupled to said implement end of said tilt cylinder, and (ii) said front end is mechanically couplable to said implement; and a front tilt link having a lever end and a lift arm end, wherein (i) said lever end of said front tilt link is pivotally coupled to said front tilt lever at a position which is interposed between said rear end and said front end of said front tilt lever, and (ii) said lift arm end of said front tilt link is pivotally coupled said box boom lift arm.
  • 3. The assembly of claim 2, further comprising an implement coupler, wherein:said implement coupler is couplable to said implement, said front tilt lever is pivotally coupled to said implement coupler, and said box boom lift arm is pivotally coupled to said implement coupler.
  • 4. The assembly of claim 1, wherein:said first extension is pivotally couplable to said frame, and said second extension is pivotally couplable to said frame.
  • 5. The assembly of claim 2, wherein:said implement end portion includes a third extension and a fourth extension spaced apart from each other so as to define a second link space therebetween, and said front tilt link extends through said second link space.
  • 6. The assembly of claim 5, wherein:said first extension is pivotally couplable to said frame, and said second extension is pivotally couplable to said frame, said third extension is mechanically couplable to said implement, and said fourth extension is mechanically couplable to said implement.
  • 7. The assembly of claim 6, further comprising an implement coupler, wherein:said implement coupler is couplable to said implement, said third extension is pivotally coupled to said implement coupler, and said fourth extension is pivotally coupled to said implement coupler.
  • 8. The assembly of claim 1, wherein:said frame end portion of said box boom lift arm is couplable to said frame at a first frame area, said first end of said rear tilt link is couplable to said frame at a second frame area, and said first frame area is located vertically above said second frame area.
  • 9. A linkage assembly for connecting an implement to a frame of a work machine, comprising:a box-boom lift arm having a frame end portion and an implement end portion, wherein (i) said frame end portion is pivotally couplable to said frame, (ii) said implement end portion is pivotally couplable to said implement, (iii) said box-boom lift arm includes an upper arm segment and a lower arm segment, and (iv) said upper arm segment includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween; a lift cylinder having a frame end and a lift arm end, wherein (i) said frame end is pivotally couplable to said frame, and (ii) said lift arm end is pivotally coupled to said box-boom lift arm; a rear tilt lever having a cylinder end and a link end, wherein (i) said link end is mechanically couplable to said frame, (ii) said rear tilt lever is pivotally coupled to said box-boom lift arm at a location which is interposed between said cylinder end and said link end, and (iii) said rear tilt lever extends through said first lever space; and a tilt cylinder having a lever end and an implement end, wherein (i) said lever end is pivotally coupled to said cylinder end of said rear tilt lever, and (ii) said implement end is mechanically couplable to said implement.
  • 10. The assembly of claim 9, further comprising:a rear tilt link having a first end and a second end, wherein (i) said first end is pivotally couplable to said frame, and (ii) said second end is pivotally coupled to said link end of said rear tilt lever.
  • 11. The assembly of claim 9, further comprising:a front tilt lever having a rear end and a front end, wherein (i) said rear end is pivotally coupled to said implement end of said tilt cylinder, and (ii) said front end is mechanically couplable to said implement; and a front tilt link having a lever end and a lift arm end, wherein (i) said lever end of said front tilt link is pivotally coupled to said front tilt lever at a position which is interposed between said rear end and said front end of said front tilt lever, and (ii) said lift arm end of said front tilt link is pivotally coupled to said box-boom lift arm.
  • 12. The assembly of claim 11, further comprising an implement coupler, wherein:said implement coupler is couplable to said implement, said front tilt lever is pivotally coupled to said implement coupler, and said box-boom lift arm is pivotally coupled to said implement coupler.
  • 13. The assembly of claim 9, wherein:said first extension is pivotally couplable to said frame, and said second extension is pivotally couplable to said frame.
  • 14. The assembly of claim 9, further comprising a front tilt link, wherein:said lower arm segment includes a third extension and a fourth extension spaced apart from each other so as to define a second link space therebetween, and said front tilt link (i) extends through said second link space and (ii) is mechanically coupled to said tilt cylinder.
  • 15. The assembly of claim 14, wherein:said first extension is pivotally couplable to said frame, said second extension is pivotally couplable to said frame, said third extension is mechanically couplable to said implement, and said fourth extension is mechanically couplable to said implement.
  • 16. The assembly of claim 15, further comprising an implement coupler, wherein:said implement coupler is couplable to said implement, said third extension is pivotally coupled to said implement coupler, and said fourth extension is pivotally coupled to said implement coupler.
  • 17. The assembly of claim 9, wherein:said frame end portion of said box-boom lift arm is couplable to said frame at a first frame area, said first end of said rear tilt link is couplable to said frame at a second frame area, and said first frame area is located vertically above said second frame area.
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Entry
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