Cab window lock system

Abstract
A lock system is made in a combination of a rotatable latch and a release lever for restricting the turn of the latch in a disengaging direction. The lock system further includes a release lever disengagement maintaining mechanism which engages with the release lever to maintain it in its disengaging condition wherein the latch is disengaged from the release lever. The release lever disengagement maintaining mechanism is designed to release the release lever from its disengaging condition when the latch turns through a specified rotation angle. Lock mechanisms are provided for a lift open type window which can be housed by moving a movable window frame upward from a window closing upright position, being guided by a pair of guide rails. The lock mechanisms are respectively attached to both ends of a top part of the window frame, so as to be exterior to the window frame and interior to and under the guide rails. Each lock mechanism has a turnable latch having two engagement notches at positions which are a specified rotation angle displaced from each other and a release lever for restricting the turn of the latch and for disengaging the latch. There are also provided strikers at the upper part of a window frame's home position where the window frame stands up and at the end of a window housing position. These strikers are respectively attached to a support structure so as to be parallel with the axis of rotation of the latch, and respectively come into engagement with their corresponding engagement notches of the latch to hold the window frame.
Description




TECHNICAL FIELD OF THE INVENTION




The present invention generally relates to a cab window lock system installed in a cab of a construction machine, and more particularly, to a cab window lock system for locking, at a desired position, a cab window such as a front window which is openable by pulling-up operation.




BACKGROUND ART




An openable front window is usually provided for, for instance, a cab of a construction machine, at the front part thereof, for viewing the state of operation being carried out with the front implements. A typical front window is designed to be retractable to its housing position, by pulling it once frontward, pulling it up and backward, and then moving it to the ceiling side of the cab.




Generally, this front window should be fixedly installed on the front side of the cab such that rain and dust cannot penetrate into the cab from outside when it is in service, and should be stably held at its housing position when it is opened. To this end, such a front window is conventionally provided with a lock mechanism of the bolt (lock pin) type such as disclosed in Japanese Patent Publication (KOKAI) Gazette No. 10-311061 (1998). This mechanism has lock pins which are disposed on both ends of the top portion of a window frame so as to be fittable in engagement holes defined on the front pillars of the cab etc. At the time of opening or closing the window, the window is unlocked or locked, by pulling out or inserting the lock pins of the lock system relative to the holes. This prior art lock mechanism includes a holding mechanism in which holding levers are automatically brought into engagement with a roller shaft of the window frame upon arrival of the window frame at its travel end when it is moved to its housing position so that the window frame is held so as not to move back from the housing position.




In place of the above lock-pin type lock mechanism, another lock mechanism is proposed in Japanese Patent Publication (KOKAI) Gazette No. 10-311062 (1998) according to which latches are provided so as to rotate into engagement with strikers fixedly mounted on a structure (the body of a cab). In this lock mechanism, strikers in the form of (Japanese katakana letter “ko”) are secured to the body of a cab, while two plate members each having an engagement groove are attached through brackets to a movable window frame at its upper and lower positions so as to work and turn in cooperation. When these plate members are released from a fastened condition by one release lever, the opposed engagement grooves of the plate members are respectively opened to the strikers by virtue of the force of torsion springs, receiving the strikers in a biting manner so that the engagement grooves are brought into locking engagement with the strikers. For unlocking the window, the plate members are respectively turned by the release lever in the direction opposite to the turning direction adapted at the time of engagement so that disengagement is established.




Japanese Patent Publication (KOKAI) Gazette No. 8-312220 discloses a lock mechanism having one latch capable of engaging with a moveable member provided at a home position and another moveable member provided at a position to which a door is moved. This mechanism uses, in combination, lock grooves (notches) formed on a turnable lock plate so as to be oriented in two different directions and a lock releasing lever for restricting the turn of the lock plate. When opening or closing the sliding door, a handle is operated to release the lock plate from the restriction by the lock releasing lever, so that the lock grooves of the lock plate are disengaged from lock pieces as the door moves. Then, upon arrival of the door at its sliding end, the lock grooves come in contact with lock pieces provided at this position so that the door is locked.




However, the lock-pin type lock mechanism of Japanese Patent Publication No. 10-311061 has a problem in its operablility that the lock pins have to be positioned relative to the lock holes for insertion and have to be anchored in the lock holes by rotation in order to prevent them from coming off. In addition, it is necessary to provide a radial gap between each pin and each pin hole (i.e., lock hole) in order to facilitate the positioning of the lock pin relative to the pin hole for insertion. The front window chatters with vibration all the more for the gap, generating noise and causing wear of the pin hole which brings about further vibration.




Another disadvantage of the system of this publication is that it needs a lock mechanism for locking the front window at the fixed position and a holding mechanism for holding it at the housing position, these mechanisms being different in structure. This is because the direction of locking the front window is utterly different from the direction of holding it. Therefore, the locking operation and the unlocking operation differ from each other, which leads to poor operability.




The lock mechanism having a latch and disclosed in Japanese Patent Publication No. 10-311062 involves a complex structure in which two plate members which respectively have an engagement groove are vertically arranged in an opposed relationship and these plate members cooperate to open and close their engagement grooves. In addition, this lock mechanism effectively functions in locking a window in an upright condition but cannot provide good stability when it is applied to the window in other conditions.




The lock mechanism disclosed in Japanese Patent Publication No. 8-312220 is advantageous in that two-directional operation can be performed, but the arrangement disclosed in this publication is insufficient to lock or hold the window frame at its travel end by use of only one latch (lock plate), the window frame being movable while changing its posture from an upright condition to a horizontally lying condition. More concretely, two different functions are required in locking and holding the window frame which moves upward changing its posture from an upright condition to a horizontally lying condition, one being a function for locking the window so as to press the window frame against a support structure at the periphery of the window when the window frame is in its upright position, while the other being a function for supporting the window frame which is coming down because of gravity and holding it so as not to move back when the window frame is in its upper, housing position. There is a difficulty in adapting the latch mechanism disclosed in the above publication to a cab window which requires the above functions.




The present invention is directed to overcoming the foregoing problems. Therefore, a first object of the invention is to provide a cab window lock system which is simple in structure and enables stable, easy locking operation and unlocking operation.




A second object of the invention is to provide a cab window lock system capable of reliably closing and fixing a window of the lift open type at its closing position, and reliably holding and housing it at its upper housing position.




DISCLOSURE OF THE INVENTION




The first object of the invention can be achieved by a cab window lock system according to a first aspect of the invention.




This lock system is composed of lock mechanisms each comprising a turnable latch and a release lever for restricting the turn of the latch in its disengaging direction,




each of the lock mechanisms further comprising a release lever disengagement maintaining mechanism which comes into engagement with the release lever to keep the release lever in its disengaging condition at a disengaging position where the latch is disengaged from the release lever,




the release lever disengagement maintaining mechanism being designed to release the release lever from its disengaging condition when the latch has turned through a specified rotation angle.




According to the invention arranged as described above, if the release lever is operated to cancel the engagement between the latch and the release lever thereby unlocking the latch, the release lever disengagement maintaining mechanism is operated, in conjunction with the latch unlocking operation by the release lever, to temporarily hold the release lever to prevent it from returning. Thus, the latch becomes free and is turned by an extrinsic turning force so that the latch can be unlocked. The turn of the latch in its disengaging direction causes a shift of the position of engagement between the latch and the release lever, and accordingly, the latch works on the release lever disengagement maintaining mechanism such that the release lever is released from its disengaged condition. Then, when the latch comes into engagement with a striker (closing bolt), exerting its locking function, the release lever returns to a position where it can engage with the latch.




Since the lock system of the invention is designed as described above, when the latch is unlocked by manipulating the latch release lever in releasing operation, the latch automatically becomes free, and therefore there is no need to hold nor handle the release lever afterward. This arrangement contributes to improved operability, particularly where a plurality of lock mechanisms need to be unlocked.




In the invention, the release lever disengagement maintaining mechanism comprises: a release lever latch which is supported on a support shaft of the latch and which is turnable together with the latch only when the latch turns in its disengaging direction; a striker which is disposed adjacently to an engagement end of the release lever for holding the release lever; and a spring for energizing the release lever latch such that the release lever latch turns in a returning direction. With this arrangement, the mechanism for maintaining the release lever in its disengaged condition can be disposed coaxially with the latch, which makes the whole system compact and reduces the number of parts, resulting in a saving of cost.




In this case, the release lever latch preferably includes an engagement recess which comes into engagement with the striker for bringing the release lever to a stop and a projection which extends continuously from the engagement recess. The distal end of the projection is preferably arranged such that the striker is positioned within the radius of gyration of the distal end of the projection when the latch is kept in its engaged condition by the release lever, and such that the striker reaches a position beyond the radius of gyration of the distal end of the projection when the release lever is shifted until the latch's engaged condition by the release lever is cancelled. With this arrangement, at an instant when latch disengaging operation is performed by the release lever, the striker attached to the distal end of the release lever comes in contact with the distal end of the projection of the release lever latch so that the release lever is prevented from returning, whereby the release lever can be reliably maintained in its disengaged condition. Additionally, the turn of the latch after the disengagement permits the striker formed on the release lever to be restorable and when the latch is engaged the next time, the release lever can be stably maintained in its engaged condition with the striker being positioned within the radius of gyration of the distal end of the projection.




The release lever disengagement maintaining mechanism may comprise a lock claw piece having a base pivotally supported in the neighborhood of the engagement end of the release lever and a distal end facing the distal end of the release lever; an operating pin attached to the lock claw piece for operating the lock claw piece by the turn of the latch; and a spring for energizing the lock claw piece so as to invariably move in the direction of the axis of rotation of the latch, and the striker may be operated by the lock claw piece. The striker may be located within the radius of gyration of the distal end of the lock claw piece when the latch is in its engaged condition and the striker may reach a position beyond the radius of gyration of the distal end of the lock craw piece when the release lever is shifted until the latch's engaged condition is cancelled.




With this arrangement, when unlocking the window by operating the release lever so as to be disengaged from the latch, the projection formed on the outer side face of the latch-engagement end of the release lever is brought into contact with the distal end of the lock claw piece to push the lock claw piece outward. Then, the lock claw piece pivots on the pivotal point on the base, so that the lock claw piece is disconnected from the projection on the latch engagement end of the release lever and the projection is anchored after moving to a position beyond the distal end of the lock claw piece. As a result, the latch can freely rotate in a disengaging direction by virtue of a rotation force caused by an energized, torsion spring or the like and is disengaged from the striker, thereby unlocking the structure (such as a door and window) to which the lock system is attached. When the latch turns, the peripheral face of the latch pushes the operating piece outward, thereby moving the lock claw piece outward to make the release lever free, so that the release lever returns to the latch side. Therefore, when the latch is engaged with the striker in the next time, the engaging part of the latch can engage with the engagement end to enable locking. In this way, the release lever disengagement maintaining mechanism can surely release the release lever in conjunction with a latch disengaging operation without difficulties. After being released, the release lever can be automatically restored in conjunction with the disengagement of the latch so that it is ready for the next locking operation.




The second object can be accomplished by a cab window lock system constructed according to a second aspect of the invention.




This lock system is designed to accommodate a window frame in its housing position such that the window frame is oriented in a direction transverse to the direction in which the window frame is oriented when it is in its upright-standing home position, by moving the window frame upward from the upright-standing home position, the window frame being movable along a pair of guide rails attached to a support structure. This lock system is constructed such that lock mechanisms are respectively attached to both ends of a top part of the window frame, so as to be exterior to the window frame and interior to the guide rails in the direction of width, each of the lock mechanisms having a latch including two engagement notches at positions which are a specified angle displaced from each other and a release lever for restricting the turn of the latch and disengaging the latch, and such that strikers are respectively disposed at the upper part of the upright-standing home position for the window frame and at the terminal end of the housing position for the window frame, for engaging with the engagement notches of the latches to hold the window frame, the strikers being attached to the support structure so as to be parallel with the axis of rotation of the latches.




In the invention thus designed, each of the lock mechanisms disposed at both ends of the top part of the window frame includes a turnable latch provided with two engagement notches having different engaging directions. At the window locking position in which the window is closed and at the housing position in which the window frame is housed after moving upward sequentially to opening of the window, the window frame can be fixedly positioned, by changing the engaging direction of the latch according to a change in the posture of the window frame by means of the strikers attached to the support structure and the engagement notches formed in the latch. With this arrangement, the window frame can be securely, reliably fixed and held by only one latch even though the window frame assumes different postures. In addition, since the lock system can be made in a simple structure provided with one turnable latch and a release lever for restricting the turn of the latch (i.e., locking) and disengaging the latch (i.e., unlocking), installation space can be saved and the window frame can be easily pulled up from its upright standing condition in order to house it.




In the invention, preferably, each of the latches has an engagement notch which comes into engagement with a first striker at a position above a rotating support shaft in order to lock the window when the window is closed, the first striker being fixedly supported by the support structure so as to project therefrom; and has an engagement notch which comes into engagement with a second striker at a position below the rotating support shaft in order to hold the window frame when the window frame is at the window-opening, housing position, the second striker being fixedly supported in the window-opening, housing position by the support structure so as to project therefrom.




With this arrangement, when moving the window frame at the window closing position so as to be pushed forward for closing the window, one of the engagement notches is brought into engagement with the first striker disposed in the above position, whereby the latch and the release lever can be connected in the neighborhood of the window frame, resulting in a compact structure. In addition, the two engagement notches formed in the latch radially open, and the position of the first striker located in the window closing position is upper than the position of the rotating support shaft of the latch, whereas the position of the second striker located in the housing position is lower than the position of the rotating support shaft of the latch. With this arrangement, when moving the window frame toward the housing position after pulling it up and opening the window, the other engagement notch of the latch can be brought into engagement with the second striker provided in the housing position without any special operation so that lock can be established. In this way, the window can be automatically locked only by pulling up and moving the window frame toward the housing position, which leads to improved operability.




It is also preferable that a striker trapping end of the opening of each engagement notch formed in each latch is longer than a striker holding end thereof. This enables it to stably maintain the engagement/holding of the strikers when the window is locked.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is an entire perspective view of the cab of a construction machine to which a lock system according to a first embodiment of the invention is attached.





FIG. 2

is a longitudinal sectional view of the cab of the construction machine.





FIG. 3

is a cutaway front view showing the essential parts of a lock mechanism of the first embodiment.





FIG. 4

is an exploded perspective view of the lock mechanism shown in FIG.


3


.




FIGS.


5


(


a


),


5


(


b


) and


5


(


c


) are explanatory views (1) illustrating the operation of the lock mechanism of the first embodiment.




FIGS.


6


(


a


),


6


(


b


),


6


(


c


) and


6


(


d


) are explanatory views (2) illustrating the operation of the lock mechanism of the first embodiment.





FIG. 7

is a partially cutaway front view of a lock mechanism according to a second embodiment of the invention.





FIG. 8

is a partially cutaway front view of a lock mechanism according to a third embodiment of the invention.





FIG. 9

is a sectional view taken on line A—A of FIG.


8


.





FIG. 10

is an explanatory view of the lock mechanism of the third embodiment.




FIGS.


11


(


a


),


11


(


b


) and


11


(


c


) are explanatory views (1) illustrating the operation of the lock mechanism of the third embodiment.




FIGS.


12


(


a


),


12


(


b


) and


12


(


c


) are explanatory views (2) illustrating the operation of the lock mechanism of the third embodiment.





FIG. 13

is a partially cutaway sectional view of a lock system according to a fourth embodiment of the invention.





FIG. 14

is a view showing the essential parts of the lock mechanism of the fourth embodiment.





FIG. 15

is a view taken on line B—B of FIG.


13


.





FIG. 16

is an enlarged sectional view taken on line C—C of FIG.


2


.




FIGS.


17


(


a


) and


17


(


b


) are explanatory views (1) illustrating the operation of the lock mechanism of the fourth embodiment.




FIGS.


18


(


a


) and


18


(


b


) are explanatory views (2) illustrating the operation of the lock mechanism of the fourth embodiment.




FIGS.


19


(


a


),


19


(


b


) and


19


(


c


) are explanatory views (3) illustrating the operation of the lock mechanism of the fourth embodiment.











BEST MODE FOR CARRYING OUT THE INVENTION




Referring now to the accompanying drawings, a cab window lock system will be described according to preferred embodiments of the invention.




(First Embodiment)





FIG. 1

shows an entire perspective view of the cab of a construction machine to which a lock system according to a first embodiment of the invention is attached, and

FIG. 2

shows a longitudinal sectional view of the cab.

FIG. 3

is a cutaway front view showing the essential parts of the lock mechanism of the present embodiment, and

FIG. 4

is an exploded perspective view of the lock system shown in FIG.


3


.




The lock system of this embodiment is applied to a front window of the lift open type disposed on the front face of the cab of a construction machine such as power shovels. There is provided a cab body


1


having front pillars


2


at the front part thereof and a pair of guide rails


4


which extend over the front pillars


2


and over the ceiling areas


3


inside the cab. A front window


5


is disposed so as to be movable along the guide rails


4


. The front window


5


has a window frame


6


on each side of which upper and lower guide rollers


7


are rotatably mounted by means of support shafts which project from the side face of the window frame


6


. The front window


5


can be moved from the front face of the cab body


1


to a position under the ceiling areas


3


by moving the guide rollers


7


along the guide rails


4


. For pulling the front window


5


up and down, the upper part and lower part of the window frame


6


are respectively provided with window-opening/closing handles


8


,


8


′.




Each of the guide rails


4


on the cab body


1


is formed such that its lower end


4




a


projects forward from the portion which extends along the front pillar


2


and such that, at the upper front of the cab body


1


, a branched portion


4




b


projects forward from a curved portion


4




c


which curves toward the ceiling area


3


of the cab body


1


.




A pane of glass


6




a


is fixed in the front window


5


by a plurality of clamps (not shown) which are arranged at specified intervals on the front side of the window frame


6


having a known structure. Each lower guide roller


7


is received by the lower end


4




a


of the guide rail


4


when the front window


5


is in its closed position, and as each upper guide roller


7


moves forward along the branched portion


4




b


of the guide rail


4


, the front window


5


is pressed against the front pillars


2


with the periphery of the front face of the glass


6




a


coming in contact, in a watertight manner, with the sealing member attached to the cab body


1


.




There are provided lock mechanisms


10


which are symmetrically laterally attached to the right and left upper parts of the inner side of the front window


5


, being respectively supported by the window frame


6


. In each of the lock mechanisms


10


, a latch


14


is rotatably mounted outside the window frame


6


. At the closing position where the front window


5


is closed, a striker


30


is attached to the cab body


1


through a clamp


31


so as to project therefrom in parallel with a support shaft


13


of the latch


14


.




These lock mechanisms


10


are laterally, symmetrically disposed and therefore one (the left one when viewed from the operator's seat) of them will be concretely described.




The lock mechanism


10


is composed of a combination of (i) a bracket


11


projecting inwardly from the upper part of the window frame


6


in a direction to cross the window glass


6




a


at right angle; (ii) a frame


12


composed of two pieces the base of which are attached to the bracket


11


with bolts


33


; (iii) a latch


14


rotatable about the support shaft


13


which is supported by the frame


12


at both ends, extending in parallel with the window glass


6




a


; (iv) a striker


30


projecting from the cab body


1


in parallel with the support shaft


13


; (v) a release lever


15


for disengaging the latch


14


from the striker


30


; (vi) a release lever disengagement maintaining mechanism


20


for keeping the release lever


15


in its disengaged condition after the latch


14


has been released from a locked condition.




The latch


14


is provided with an engagement notch


14




a


formed at a position located outwardly radially away from the center of rotation. On the periphery of the latch


14


, an engagement recess


14




b


is located oppositely to the engagement notch


14




a


with the support shaft


13


between. Fitted on the support shaft


13


for the latch


14


is a torsion spring


17


one end of which is engaged with the frame


12


while the other end being engaged with the latch


14


in place, whereby a turning force is constantly applied to the latch


14


in a clockwise direction on the plane of the drawing.




For such a latch


14


, a release lever


15


is provided. This release lever


15


includes a pivotal shaft pin


16


having a center in a vertical plane (that is parallel with the window frame


6


in the drawing) which passes the center of the support shaft


13


. The release lever


15


has an engagement end portion


15




a


which extends from the pivotal shaft pin


16


to the distal end of the release lever


15


. The release lever


15


has such a relationship with the latch


14


that when the engagement end portion


15




a


has been brought into engagement with the engagement recess


14




b


of the latch


14


, the latch


14


is locked. The release lever


15


is provided with a torsion spring


17


′ for pulling the release lever


15


back. The fixed end of the torsion spring


17


′ is secured to the frame


12


, so that the release lever


15


can return automatically after it has been released from its disengaged condition.




A striker


18


projects in parallel with the pivotal shaft pin


16


from a position on a side face of the release lever


15


, the position being close to the engagement end portion


15




a


of the release lever


15


. The striker


18


functions in cooperation with the release lever disengagement maintaining mechanism


20


described later.




The release lever disengagement maintaining mechanism


20


has, as a main component, a release lever latch


21


rotatably disposed on the support shaft


13


of the latch


14


so as to be parallel with the latch


14


. The mechanism


20


also has a torsion spring


24


for invariably applying a turning force to the release lever latch


21


in such a direction (counter-clockwise direction on the plane of the drawing) to close the latch


21


. When an engagement recess


21




a


of the release lever latch


21


is engaged with the striker


18


provided for the release lever


15


, the latch


14


is kept to be in a locked condition. For unlocking the latch


14


, the striker


18


of the release lever


15


is moved away from the latch


14


, thereby making the latch


14


free.




The release lever latch


21


comprises (i) an engagement recess


21




a


which is rotatably supported on the support shaft


13


, for bringing the release lever


15


to a stop by engaging with the striker


18


disposed at the engagement end portion


15




a


of the release lever


15


; (ii) a hook-like projection


22


which continuously extends from the engagement recess


21




a


and projects in a circumferential direction; and (iii) an engagement piece


23


disposed at a position a specified rotation angle away from the projection


22


and curved toward the peripheral face of the latch


14


so as to be parallel with the axis of the support shaft. The release lever latch


21


is normally held by the accumulated force of the torsion spring


24


with the striker


18


of the release lever


15


being engaged with the engagement recess


21




a


, as described earlier (see FIG.


3


).




The projection


22


of the release lever latch


21


has a sharpened distal end


22




a


. When the release lever


15


is turned to the position of a stopper


19


mounted on the frame


12


with the radius of gyration r with which the striker


18


attached to the release lever


15


turns in releasing operation, the striker


18


gets out of the turning range (with the radius of gyration R) of the distal end


22




a


of the projection


22


of the release lever latch


21


, and is prevented from moving back by the distal end


22




a


of the projection


22


.




The engagement piece


23


of the release lever latch


21


functions to restrain the turning movement of the release lever latch


21


which is turned by the accumulated force of the torsion spring


24


, upon disengagement of the striker


18


from the projection


22


which extends from the engagement recess


21




a


after the latch


14


is disengaged by the release lever


15


. Specifically, the engagement piece


23


comes in contact with an engagement part


14




c


which is formed on the peripheral face of the latch


14


, being located between the engagement recess


14




b


and the engagement notch


14




a


, so that the release lever latch


21


does not turn further.




The frame


12


for supporting the latch


14


and release lever


15


thus arranged as well as the release lever disengagement maintaining mechanism


20


is constructed as a combination of two frame pieces


12




a


,


12




b


as described earlier. Concretely, the latch


14


, the release lever


15


and the release lever disengagement maintaining mechanism


20


are housed in the space defined by the frame pieces


12




a


and


12




b


which are combined together. The space defined by the frame


12


is open to above in order to allow the engagement and disengagement between the latch


14


and the striker


30


positioned on the side of the main body. A handle


15




b


for manipulating the release lever


15


projects through an opening


12




d


which is formed by partially cutting away the underside of the frame


12


, so that the handle


15




b


can be operated from outside. Reference numerals


12




e


,


12




e


′ designate mounting holes for the support shaft


13


of the latch


14


. Reference numerals


12




f


and


12




g


designate a supporting hole for the pivotal shaft pin


16


of the release lever


15


and a mounting bolt hole for the bracket


11


, respectively.




Next, the operation of the lock mechanism of the first embodiment will be described with reference to

FIGS. 5 and 6

.




For unlocking the lock mechanism


10


when opening the front window


5


by pulling up, the handle


15




b


of the release lever


15


is pulled in the direction of arrow a in FIG.


5


(


a


). The lever


15


then pivots on the pivotal shaft pin


16


so that the engagement end portion


15




a


is moved away from the engagement recess


14




b


of the latch


14


as shown in FIG.


5


(


b


).




By further operating the release lever


15


, the striker


18


disposed at the distal end of the release lever


15


is moved away from the engagement recess


21




a


of the release lever latch


21


. Then, the release lever


15


moves until it comes in contact with the stopper


19


so that its turn is restricted. At the time when the release lever


15


has contacted the stopper


19


, the striker


18


has moved beyond the radius of gyration R of the distal end


22




a


of the projection


22


formed in the release lever latch


21


, as shown in FIG.


5


(


c


).




When the lock mechanism is in the condition shown in FIG.


5


(


c


), the latch


14


is completely free from the release lever


15


. Therefore, the latch


14


turns clockwise on the plane of the drawing (in the direction of arrow b) by virtue of the returning force of the torsion spring


17


(see

FIG. 4

) attached to the latch


14


, as shown in FIG.


6


(


a


). At the same time, the engagement end portion


15




a


of the release lever


15


comes into contact with the peripheral face between the engagement recess


14




b


and engagement part


14




c


of the latch


14


so that the latch


14


will not be locked again.




When the latch


14


further turns in the direction of arrow b, the engagement piece


23


formed at the end of the release lever latch


21


, which turns in the direction opposite to the turning direction of the latch


14


by virtue of the returning force of the torsion spring


24


, comes into engagement with the engagement part


14




c


formed on the periphery of the latch


14


, the part


14




c


having been away from the engagement piece


23


by that time, so that the release lever latch


21


turns and moves back together with the latch


14


(see FIG.


6


(


b


)).




The turn of the latch


14


allows the striker


30


, which has been in engagement with the engagement notch


14




a


, to start coming off the engagement notch


14




a


. Accordingly, when manipulating the window opening/closing handles


8


,


8


′ to pull the window frame


6


up for opening the front window


5


, the latch


14


is actively turned by this pull-up force, as shown in FIG.


6


(


c


), causing a reaction force of the striker


30


which has been in engagement with the engagement notch


14




a


of the latch


14


. Then, the latch


14


is separated from the striker


30


(see FIG.


6


(


d


)) so that the window frame


6


can be pulled up (pushed up) along the guide rails


4


toward the underside of the ceiling for storing.




As mentioned above, when the lock mechanism


10


is in its unlocked condition, the engagement end portion


15




a


of the release lever


15


is in contact with the peripheral face of the latch


14


, being kept off the engagement recess


14




b


, while the latch


14


and the release lever latch


21


are well balanced with the engagement part


14




c


being in engagement with the engagement piece


23


, as shown in FIG.


6


(


d


). This condition is maintained until the front window


5


is closed again.




For closing and locking the front window


5


, the window frame


6


is pushed into the locked position, while the latch


14


of the lock mechanism


10


being kept in its unlocked condition (shown in FIG.


6


(


d


)) as described above. Then, an opening inner edge


14




a


′ of the engagement notch


14




a


of the latch


14


touches the striker


30


which is in its home position, so that the edge


14




a


′ is pushed back by the striker


30


(see FIG.


6


(


c


)). In reaction to this, the latch


14


turns in the direction opposite to the aforesaid direction to receive the striker


30


within the engagement notch


14




a.






After that, the reverse turn of the latch


14


allows the engagement end portion


15




a


of the release lever


15


, which has been in contact with the peripheral face of the latch


14


, to be shifted to a position where the peripheral face of the latch


14


terminates. The engagement end portion


15




a


is then moved back and brought into engagement with the engagement recess


14




b


of the latch


14


by virtue of the accumulated force of the torsion spring


17


′ fitted on the pivotal shaft pin


16


of the release lever


15


. As a result, the latch


14


is locked by the release lever


15


.




(Second Embodiment)





FIG. 7

shows a partially cutaway front view of a lock mechanism constructed according to a second embodiment of the invention. The basic structure of the lock mechanism


10


A of the second embodiment is similar to that of the first embodiment except that a release lever latch


21


A of a release lever disengagement maintaining mechanism


20


A and a striker


18


A attached to the release lever


15


are different in shape from those of the first embodiment. Therefore, those parts in the second embodiment that find their equivalents in the first embodiment are indicated by the same numerals as used in the first embodiment, and explanation on them will be omitted.




In the release lever disengagement maintaining mechanism


20


A of the second embodiment, an engagement recess


21




a


′ of the release lever latch


21


A is more deeply gouged than that of the first embodiment, and accordingly a projection


22


A which continuously extends from the engagement recess


21




a


′ has a more elongated hook-like shape. The engagement piece


23


attached to the release lever latch


21


A is designed to invariably contact the engagement part


14




c


of the latch


14


so that the release lever latch


21


A turns together with the latch


14


. The striker


18


A attached to the distal end of the release lever


15


is formed so as to have a section in the form of a circle which is partially cut off on the side facing the release lever latch


21


A. Except the above features, the release lever disengagement maintaining mechanism of the second embodiment is similar to that of the first embodiment.




The parts which constitute the lock mechanism


10


A of the second embodiment having the above features operate and function in the same way as explained in the foregoing description, but the structural feature inherent to the second embodiment is as follows. The engagement recess


21




a


′ of the release lever latch


21


A is deeply gauged, and when the latch


14


is in its locked condition, the engagement piece


23


attached to the release lever latch


21


A is in contact with the engagement part


14




c


of the latch


14


invariably so that the release lever latch


21


A is operated together with the latch


14


. Therefore, the release lever latch


21


A is maintained to be out of contact with the striker


18


A provided for the release lever


15


when the latch


14


is in its locked condition, so that the release lever


15


does not receive external force from the window frame


6


side. This arrangement permits the release lever


15


to withstand long use.




(Third Embodiment)




Next, a lock mechanism


10


B constructed according to a third embodiment of the invention will be described.

FIG. 8

shows a partially cutaway front view of the lock mechanism


10


B of the third embodiment.

FIGS. 9 and 10

show a sectional view taken along line A—A in FIG.


8


and an explanatory view of a release lever holding mechanism, respectively.




The lock mechanism


10


B of the third embodiment is substantially similar to the lock mechanism


10


of the first embodiment except the release lever disengagement maintaining mechanism


20


B. Therefore, those parts in the third embodiment that find their equivalents in the foregoing embodiments are indicated by the same numerals as used in the foregoing embodiments, and explanation on them will be omitted. Note that the same numeral is given to the latch for locking the open or closed window.




The latch


14


is provided with the engagement notch


14




a


formed at a position located outwardly radially away from the center of rotation. On the periphery of the latch


14


, a first engagement recess


14




b


and a second engagement recess


14




d


are disposed oppositely to the engagement notch


14




a


with the support shaft


13


between. Fitted on the support shaft


13


of the latch


14


is the torsion spring


17


. One end of the torsion spring


17


is engaged with the frame


12


while the other being engaged with the latch


14


in place, so that a turning force is exerted at all times in a clockwise direction on the plane of the drawing.




The release lever


15


is provided for the latch


14


thus arranged in such a manner that the center of the pivotal shaft pin


16


is located on a vertical plane (a plane parallel with the window frame


6


in the drawing) which passes the center of the support shaft


13


. The release lever


15


has the engagement end portion


15




a


which extends from the pivotal shaft pin


16


to the distal end of the release lever


15


. By bringing the engagement end portion


15




a


into engagement with the first engagement recess


14




b


of the latch


14


, the latch


14


is locked. It should be noted that the release lever


15


is provided with a torsion spring (not shown) which returns upon cancel of engagement (this spring is the same as that of the first embodiment).




The striker


18


projects in parallel with the pivotal shaft pin


16


from a position on the side of the release lever


15


, the position being close to the engagement end portion


15




a


. The striker


18


is related to a release lever disengagement maintaining mechanism


20


B described later.




The release lever disengagement maintaining mechanism


20


B has, as a main component, a turnable lock claw piece


26


the base of which is supported by a pivotal shaft


25


which is disposed on the side of the latch


14


so as to be parallel with the support shaft


13


. Disposed between the lock claw piece


26


and the frame


12


for supporting the essential parts of the lock mechanism


10


B is a spring (not shown) for invariably applying a turning force to the lock claw piece


26


to turn it toward the support shaft


13


of the latch


14


. As this spring means (not shown), a torsion spring is fitted on the pivotal shaft


25


, or alternatively, an extension spring is tensioned between a suited position of the lock claw piece


26


and a suited position of the frame


12


.




The lock claw piece


26


is sharpened at its distal end


26




a


. When the region having a length L, which extends from the center of the pivotal shaft


25


positioned at the base of the lock claw piece


26


to the distal end


26




a


, does not project into the region of the radius of gyration r of the striker


18


(when turning in disengaging operation) attached to the release lever


15


as shown in FIG.


10


and the engagement end portion


15




a


of the release lever


15


is in its locked condition, being in engagement with the first engagement recess


14




b


of the latch


14


, the side face of the distal end


26




a


of the lock claw piece


26


is in contact with the striker


18


.




The lock claw piece


26


is provided with an operating pin


27


which is parallel with the pivotal shaft


25


and located at an intermediate position which is a proper distance away from the pivotal shaft


25


toward the distal end of the lock claw piece


26


. The operating pin


27


is normally in contact with the peripheral face of the latch


14


between the first engagement recess


14




b


and the second engagement recess


14




d


to control the lock claw piece


26


. Reference numeral


19


designates a stopper for restricting the turning range of the release lever


15


.




With reference to

FIGS. 11 and 12

, the operation of the lock mechanism


10


B of the third embodiment will be explained below. For pulling up the front window


5


to open it, when a handle


15


′ of the release lever


15


is pulled in the direction of arrow a in FIG.


11


(


a


) to unlock the lock mechanism


10


B, the release lever


15


is turned on the pivotal shaft pin


16


and the engagement end portion


15




a


is moved away from the engagement recess


14




b


of the latch


14


as shown in FIG.


11


(


b


).




Then, the release lever


15


is further turned whereby the striker


18


attached to the distal end of the release lever


15


is brought into contact with the side face of the distal end of the lock claw piece


26


to push the lock claw piece


26


back against the returning spring force. Thereafter, the release lever


15


moves until it touches the stopper


19


at its intermediate position and its turning movement is restricted. Just before the restriction by the stopper


19


, the striker


18


comes in contact with the outer side face of the lock claw piece


26


, moving beyond the radius (equal to the distance from the center of the proximal pivotal shaft


25


to the distal end) of gyration L of the distal end


26




a


of the lock claw piece


26


which is pushing back the side face of the striker


18


(see FIG.


11


(


c


)). As a result, the release lever


15


is held by the lock claw piece


26


, thereby making the latch


14


free.




The latch


14


is thus released from its engaged condition (unlocking), so that the latch


14


is turned in the direction of arrow b shown in FIG.


12


(


a


) by virtue of the returning force of the torsion spring


17


(see

FIG. 9

) being energized. At the same time, the operating pin


27


attached to the lock claw piece


26


comes into contact with the peripheral face of the adjacent portion of the latch


14


.




The latch


14


thus brought into a free condition is actively turned, as shown in FIG.


12


(


b


), against the striker


30


being in engagement with the engagement notch


14




a


of the latch


14


, by means of an operating force which has been applied for drawing the window frame


6


to the front side in order to pull it up with the window opening/closing handles


8


,


8


′ for opening the front window


5


. Then, the latch


14


is pulled away from the striker


30


(see FIG.


12


(


c


)) and the window frame


6


is pulled up (pushed up) along the guide rails


4


toward the underside of the ceiling for housing it.




As the free, latch


14


turns, the first engagement recess


14




b


shifts, turning in a proper amount from the engagement position at which the first engagement recess


14




b


engages with the engagement end portion


15




a


of the release lever


15


. Then, the operating pin


27


attached to the lock claw piece


26


is pushed out by a projection


14




e


which is preformed on the peripheral face of the latch


14


so as to be adjacent to the second engagement recess


14




d


, the operating pin


27


having come into contact with the latch peripheral face as the release lever


15


was anchored at its releasing operation position by the lock claw piece


26


of the release lever disengagement maintaining mechanism


20


B. Subsequently, the distal end


26




a


of the lock claw piece


26


, which works on the striker


18


attached to the distal end of the release lever


15


, thrusts the striker


18


away and then pushes the striker


18


back to the latch


14


side again. As a result, the engagement end portion


15




a


of the release lever


15


is brought into contact with the peripheral face of the latch


14


, as shown in FIG.


12


(


b


).




After the engagement notch


14




a


of the latch


14


has been disengaged from the striker


30


thereby completely unlocking the lock mechanism


10


B, the latch


14


is turned in a clockwise direction on the plane of the drawing by virtue of the returning force of the torsion spring


17


being energized. Then, the turn of the latch


14


is stopped by the engagement between the engagement end portion


15




a


of the release lever


15


which has been in contact with the latch's peripheral face and the second engagement recess


14




d


, and the latch


14


is kept in its stopped position (see FIG.


12


(


c


)).




In this way, the engagement notch


14




a


of the latch


14


is kept in such a condition that the notch


14




a


opens toward the striker


30


so as to receive it and therefore can quickly engage with the striker


30


at the time when the window is closed again. For operating the lock mechanism


10


B to lock the window frame


6


when closing the window, the latch


14


is operated in a manner reverse to the above-described unlocking operation, and therefore there is no need to manipulate the release lever


15


from outside so that the locking operation is unaffected.




The lock mechanism


10


B having the above structure includes the release lever disengagement maintaining mechanism which is different from those of the first and second embodiments and capable of facilitating the disengagement of the latch


14


by the release lever


15


.




(Fourth Embodiment)




This embodiment is associated with a structure which is applied to a lift open type cab window and enables closing/fixing of the window at the window closing position and housing/holding of the window at the upper housing position (window opening position).





FIG. 13

shows a longitudinal sectional view of the lock system of the present embodiment in which parts of the system are omitted.

FIG. 14

shows the essential parts of the lock mechanism.

FIGS. 15 and 16

show a view taken along line B—B in FIG.


13


and an enlarged sectional view taken along line C—C in

FIG. 2

, respectively. Those parts in the fourth embodiment that find their equivalents in the foregoing embodiments are indicated by the same numerals as used in the foregoing embodiments, and explanation on them will be omitted.




In the latch


14


of this embodiment, the engagement notches


14




a


,


14




b


are formed at two positions which are a rotation angle of 90° separated from each other and located outwardly radially away from the center of rotation as shown in

FIG. 14

(which shows the latch


14


on the right side when viewed from the operator's seat). The engagement notches


14




a


,


14




b


each have a semi-circular bottom. The engagement notch


14




a


has opening ends


14




c


,


14




d


at its opening side whereas the engagement recess


14




b


has opening ends


14




e


,


14




f


at its opening side, each of these ends taking the form of a circular arc. The opening ends


14




d


,


14




f


(i.e., striker trapping ends) are somewhat longer than the opening ends


14




c


,


14




e


(i.e., striker holding ends) respectively, the opening ends


14




d


,


14




f


being located behind when they receive the striker


30


(described later) whereas the opening ends


14




c


,


14




e


being opposite to the ends


14




d


,


14




f


. Engagement recesses


14




g


and


14




h


are formed at the periphery of the latch


14


so as to be opposite to the engagement notches


14




a


,


14




b


with the center of rotation of the latch


14


between.




The center of the pivotal shaft pin


16


is positioned on a vertical plane which passes the center of the support shaft


13


for rotatably supporting the latch


14


, and the release lever


15


is disposed on the side opposite to the position of the striker engaging portion when the window is in its closed position. The turn of the latch


14


is restricted by engaging the distal end portion


15




a


of the release lever


15


with the engagement recesses


14




g


,


14




h


of the latch


14


. Although not shown in the drawings, a torsion spring is fitted on the pivotal shaft pin


16


of the release lever


15


, with one end being connected to the side of a stationary member while the other end is connected to the release lever


15


in place, so that the release lever


15


can return after disengaging the latch


14


.




The latch


14


thus formed is supported on the support shaft


13


, just under the guide rail


4


for the window frame


6


, as shown in FIG.


15


. The latch


14


is provided with a torsion spring


17


which is fitted on the support shaft


13


, with one end being engaged on the bracket


11


side, while the other end is connected to the latch


14


in place. The torsion spring


17


gives a rotational returning force to the latch


14


. The latch


14


, the release lever


15


and others thus formed are supported, enclosed and protected by the frame


12


which also functions as a dividable cover. Reference numeral


19


represents a stopper for stopping the turn of the release lever


15


.




As shown in

FIG. 16

, strikers


40


are provided under the ceiling of the cab body


1


. Concretely, the strikers


40


are positioned under the guide rails


4


in the neighborhood of the end of the guide rails


4


and each of these is mounted by a clamp


41


attached to the cab body


1


in such a manner that the strikers


40


project inwardly in a horizontal condition relative to the direction of width. When the window frame


6


guided by the guide rails


4


has moved to the terminal end of the housing position, each striker


40


engages with the other engagement recess


14




b


of the latch


14


of a lock mechanism


10


C mounted on the upper part of the window frame


6


.




The opening and closing operation of the front window


5


of the present embodiment thus formed will be described with reference to

FIGS. 17

to


19


.

FIGS. 17

to


19


are shown when viewed from the side opposite to

FIG. 13

which shows a section of the window side.




For opening the window, the release lever


15


for each lock mechanism


10


C is operated to move in the direction of arrow a in FIG.


17


(


a


) (i.e., in the direction of arrow a in FIG.


13


), when the release lever


15


is in a condition shown in FIG.


17


(


a


). Then, the release lever


15


pivots on the pivotal shaft pin


16


and the distal end of the release lever


15




a


is disengaged from the engagement recess


14




g


of the latch


13


(see FIG.


17


(


b


)). It should be noted that the turn of the release lever


15


is restricted by the stopper


19


attached to the frame


12


so that the release lever


15


does not turn more than necessary.




Thereafter, the latch


14


is turned by the returning force of the torsion spring


17


mounted on the support shaft


13


, moving to the front side, which causes the reactive force of the striker


30


. As a result, the engagement notch


14




a


of the latch


14


turns and shifts in such a direction as to be separated from the striker


30


as shown in FIG.


18


(


a


), and shortly, the latch


14


is disengaged. After the disengagement of the latch


14


, the upper part of the window frame


6


to which the lock mechanisms


10


C are attached can be moved backward and released from the fixed condition. At this point, the distal end portion


15




a


of the release lever


15


has been brought into engagement with the other engagement recess


14




h


of the latch


14


so that the release lever


15


is held at this position and prevented from turning.




The window frame


6


is supported by the guide rollers


7


attached to the underside thereof being fitted in the respective lower ends


4




a


of the guide rails


4


(see FIG.


13


). Therefore, when the window frame


6


has been released from the condition wherein it is locked by the lock mechanisms


10


C, the window frame


6


can pivot on the guide rollers


7


in such a manner that its upper part moves inwardly of the cab. This permits each engagement notch


14




a


to come off the striker


30


located in the window-closing position P, so that the window frame


6


can move backward to a considerable extent as shown in FIG.


18


(


b


). Therefore, when the operator holds the lower window opening/closing handle


8


′ and the upper window opening/closing handle


8


by hands and pulls the upper part of the window frame


6


toward the operator, while lifting the window frame


6


, the upper guide rollers


7


move from the branched portions


4




b


of the guide rails


4


to the curved portions


4




c


(see

FIG. 2

) so that the window frame


6


can be directly pulled up.




By pulling the window frame


6


up in this way, the upper and lower guide rollers


7


are guided by the guide rails


4


so that the window frame


6


can move from the front face of the cab body


1


to the ceiling area without stops. Just before arrival of the window frame


6


at the housing position, the latch


14


of each lock mechanism


10


C moves such that the opening of the other engagement recess


14




b


faces its corresponding striker


40


disposed at the housing position as shown in FIG.


19


(


a


).




When the opening end


14




f


of the engagement recess


14




b


of the latch


14


touches the striker


40


, the latch


14


is turned by the striker


40


in the direction of arrow b, being guided by the circular arc face of the opening end


14




f


as shown in FIG.


19


(


b


), while the distal end portion


15




a


of the release lever


15


is pulled apart from the engagement recess


14




h


of the latch


14


. When the window frame


6


shortly arrives at the terminal end of the housing position, the latch


14


receives the striker


40


at the engagement recess


14




b


and the distal end portion


15




a


of the release lever


15


engages with the engagement recess


14




g


as shown in FIG.


19


(


c


), so that the window frame


6


is locked at this position.




In this way, the window frame


6


is locked by the lock mechanisms


10


C at its housing position, so that the cab body


1


would not slip forward even if vibration is transmitted to the cab body


1


from outside and can be safely, reliably held at the housing position.




For closing the front window


5


which has been thus opened by pulling up, the lock system is operated reversely to the above-described opening operation to pull the window frame


6


down to close the window. More concretely, when lowering the window frame


6


which is locked at its housing position, each lock mechanism


10


C is operated in such a way that the handle of the release lever


15


is pulled down from the position shown in FIG.


19


(


c


), and then, the release lever


15


turns on the pivotal shaft pin


16


so as to cancel the engagement between the distal end portion


15




a


and the engagement recess


14




g


of the latch


14


whereby the latch


14


becomes free.




Now that the window frame


6


has been brought into a freely movable condition, the window frame


6


is moved along the guide rails


4


by the window opening/closing handles


8


,


8


′. Since the latch


14


of the lock mechanism


10


C is free, the latch


14


is reversely turned by the returning force of the energized torsion spring


17


when the latch


14


is pulled apart from the striker


40


, so that the distal end portion


15




a


of the release lever


15


is again engaged with the engagement recess


14




h


and, in consequence, the window frame


6


can be restored to its initial position with the latch


14


being in the condition shown in FIG.


19


(


a


).




After the window frame


6


has been thus moved back to the front face of the cab body


1


, the guide rollers


7


attached to the underside of the window frame


6


of the front window


5


are fitted in the lower ends


4




a


of the guide rails


4


. Then, the upper part of the window frame


6


is pushed forward while its posture being adjusted, and the upper guide rollers


7


move into the branched portions


4




b


of the guide rails


4


so that the window frame


6


can be moved to the window closing position. Immediately before the movement of the window frame


6


to the window closing position, each lock mechanism


10


C is in an upright condition together with the window frame


6


and the engagement notch


14




a


of the latch


14


is kept in a condition wherein its opening side faces its corresponding striker


30


located in the window closing position, as shown in FIG.


18


(


b


).




By pushing the window frame


6


forward with the upper window opening/closing handle


8


, the opening end


14




d


of the engagement notch


14




a


of the latch


14


comes in contact with the striker


30


as shown in FIG.


18


(


a


). As the window frame


6


moves forward, the latch


14


reversely turns, and the latch


14


shortly reaches the window closing position, catching the striker


30


at the engagement notch


14




a


. Subsequently, the striker


30


is completely received within the engagement notch


14




a


of the latch


14


as shown in FIG.


17


(


a


). During this time, the distal end portion


15




a


of the release lever


15


is pulled apart from the engagement recess


14




h


and engages with the other engagement recess


14




g


, while the torsion spring


17


attached to the latch


14


is turned against the returning force and reversely energized so that energy is accumulated. By virtue of the accumulated energy of the torsion spring


17


, the engagement force of the distal end portion


15




a


of the release lever


15


which is in engagement with the engagement recess


14




g


is maintained so that the turn of the latch


14


is stopped. Namely, the latch


14


is locked and the front window


5


is anchored at the window section.




As described above, each lock mechanism


10


C incorporated in the window frame


6


includes the latch


14


having the engagement notch


14




a


which engages with the striker


30


at the window closing position and the engagement recess


14




b


which engages with the striker


40


at the housing position (window opening position), these engagement notches


14




a


and


14




b


being a predetermined rotation angle away from each other. Therefore, as the window frame


6


changes its posture from an upright condition to a lying down condition when opening or closing the front window


5


, the lock mechanism


10


C automatically changes its engagement position while the distal end portion


15




a


of the release lever


15


attached to the lock mechanism


10


C changes its engagement position from the engagement recess


14




g


to the engagement recess


14




h


of the latch


14


, whereby the striker


30


or striker


40


can engage with the engagement notch


14




a


or


14




b


without operation from outside. With this arrangement, the operator only needs to operate the release lever


15


so as to disengage the latch


14


from the striker


30


or


40


, when moving the window frame


6


to open or close the front window


5


. In consequence, the window frame can be reliably secured at the window closing position or the window opening position.




When the engagement notch


14




a


or


14




b


of the latch


14


comes into engagement with its associated striker


30


or


40


, the opening ends


14




d


or


14




f


first touches the striker


30


or


40


at the early stage of contact. These opening ends


14




d


and


14




f


are somewhat longer than the opening ends


14




c


and


14




e


, respectively, located on the opposite side. This facilitates the reception of the strikers


30


or


40


within the engagement notch


14




a


or


14




b


, thereby ensuring reliable engagement.




Since each striker


30


is located above the latch


14


at the window closing position, the upper part of the window frame can be pushed forward and locked without difficulties, and since the striker


30


presses the latch


14


downward, the vibration of the window frame can be restrained. In addition, since each striker


40


is located under the latch


14


at the housing position, the window frame


6


is locked at the housing position in such a manner that the window frame


6


is lifted by the locking section. With this arrangement, the window frame


6


does not come off the locking section even if it is subjected to vibration and, in consequence, safety can be ensured.




While the invention has been described in the context of a lock system for a front window mounted on the cab of a construction machine in the foregoing embodiments, it is equally applicable to windows of the lift open type used in houses. In cases where the invention is applied to house windows, the window lock system is not bulky and has a structure easy to handle, so that the window frame can be conveniently housed by pulling up without any troubles.



Claims
  • 1. A cab window lock system for accommodating a window frame in its window-opening, housing position such that the window frame is oriented in a direction transverse to the direction in which the window frame is oriented when it is in its upright-standing home position, by moving the window frame upward from the upright-standing home position, the window frame being movable along a pair of guide rails attached to a support structure,wherein lock mechanisms are respectively attached to both ends of a top part of the window frame, so as to be exterior to the window frame and interior to the guide rails in the direction of the width, each of the lock mechanisms having a latch including two engagement notches at positions which are a specified angle displaced from each other, two engagement recesses, and a release lever for restricting the turn of the latch and disengaging the latch by engagement with said engagement recesses, wherein strikers are respectively disposed at the upper part of the upright-standing home position for the window frame and at the terminal end of the housing position for the window frame, for engaging with the engagement notches of latches to hold the window frame, the strikers being attached to the support structure so as to be parallel with the axis of rotation of the latches.
  • 2. The cab window lock system according to claim 1, wherein each of the latches has one of said engagement notches which comes into engagement with a first striker of said strikers at a position above a rotating support shaft of said latch in order to lock the window frame when the window is closed, the first striker being fixedly supported by the support structure so as to project therefrom; and has another of said engagement notches which comes into engagement with a second striker of said strikers at a position below the rotating support shaft in order to hold the window frame when the window frame is at the window-opening, housing position, the second striker being fixedly supported in the window-opening, housing position by the support structure so as to project therefrom.
  • 3. The cab window lock system according to claim 1, wherein each engagement notch formed in each latch opens in a radial direction.
  • 4. The cab window lock system according to claim 1, wherein a striker trapping end of an opening of each engagement notch formed in each latch is longer than a striker holding end of the opening of each engagement notch formed in each latch.
Priority Claims (2)
Number Date Country Kind
11-96579 Apr 1999 JP
11-119240 Apr 1999 JP
Parent Case Info

This application is a divisional application of prior application Ser. No. 09/540,872 now U.S. Pat. No. 6,474,705 filed Mar. 31, 2000.

US Referenced Citations (6)
Number Name Date Kind
1580666 Hansen Apr 1926 A
3905626 Myers Sep 1975 A
4835997 Akright Jun 1989 A
4986593 Lohmann Jan 1991 A
5025880 Kato Jun 1991 A
5096253 Jo et al. Mar 1992 A
Foreign Referenced Citations (6)
Number Date Country
2821364 Dec 1978 DE
8-312220 Nov 1996 JP
10-311061 Nov 1998 JP
10-311062 Nov 1998 JP
11-181833 Jul 1999 JP
11-324019 Nov 1999 JP