Backhoe unit detachably attached to a tractor

Abstract

A backhoe unit detachably attached to a backhoe mounting frame disposed on a tractor body rearwardly of a driver's seat. The backhoe unit includes a base having engaging portions for connection to the backhoe mounting frame, a driver's footrest and a control column disposed on the base, a vertical swing axis supported by the base, a boom bracket supported to be swingable about the vertical swing axis, and a boom assembly attached to the boom bracket. The boom bracket is swung horizontally by a single swing cylinder having one end thereof connected to the base through a first cylinder connecting portion, and the other end connected to the boom bracket through a second cylinder connecting portion. The swing cylinder is disposed in a lateral position of the base.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a backhoe unit detachably attached to a backhoe mounting frame disposed on a tractor body rearwardly of a driver's seat.

2. Description of the Related Art

Conventionally, this type of backhoe unit is applied to a tractor known as a TLB (tractor-loader-backhoe) having a loader attached to the front of a vehicle body and the backhoe unit to the rear of the vehicle body. In such a TLB, as disclosed in Japanese Patent Laying-Open Publication H10-7014 and U.S. Pat. No. 6,056,502, a backhoe mounting frame is disposed at the rear of a tractor body, and a base that supports a backhoe unit is detachably attached to this backhoe mounting frame. The base includes a pair of right and left stabilizers and a vertical swing axis about which a boom bracket is swingable. A boom assembly is attached to the boom bracket. The boom bracket is horizontally swung by a pair of right and left swing cylinders. The right and left swing cylinders are the trunnion type distributed laterally of the center of the base, and arranged to extend parallel to each other in the fore and aft direction of the tractor body. Thus, fore and aft long spaces are required for accommodating the swing cylinders. In addition, four hydraulic hoses are needed for the two swing cylinders requiring a large accommodation space also. The entire base therefore has in a large fore and aft dimension, resulting in an increased fore and aft length of the backhoe unit. The backhoe unit when attached imposes a considerable load on the tractor body.

The base of the backhoe unit has a footrest formed thereon, and a control column of rectangular cross section is disposed in a transversely middle position in a rearward region of the footrest. In a large TLB, spaces are formed between right and left rear wheel fenders and right and left sides of the control column of the backhoe unit attached, thereby providing walkthrough spaces for the driver which extend longitudinally of the tractor body.

However, in small and medium-size TLBs, only narrow spaces are formed between the right and left rear wheel fenders and the right and left sides of the control column. The control column must be disposed further rearward from the rear wheel fenders to produce walkthrough spaces extending transversely of the tractor body. This results in an increased distance from the rear end of the tractor body to the control column of the backhoe unit attached, thereby increasing the total length of the backhoe unit, particularly the fore and aft dimension of the base. The increased fore and aft dimension of the base is detrimental to the weight balance of the TLB.

SUMMARY OF THE INVENTION

The object of this invention is, starting from a backhoe unit including a base having engaging portions for connection to the backhoe mounting frame, a driver's footrest and a control column disposed on the base, a vertical swing axis supported by the base, a boom bracket supported to be swingable about the vertical swing axis, and a boom assembly attached to the boom bracket, to overcome the disadvantages of the prior art noted above, and provide a compact backhoe unit that secures walkthrough spaces for the driver to climb up to and down from the footrest on the base with ease.

The above object is fulfilled, according to this invention, by a backhoe unit in which the boom bracket is swung horizontally by a single swing cylinder having one end thereof connected to the base through a first cylinder connecting portion, and the other end connected to the boom bracket through a second cylinder connecting portion, the swing cylinder being disposed in a lateral position of the base. With this construction, since the boom bracket of the backhoe unit is swung by a single swing cylinder, a construction relating to the swing cylinder is simplified, space may be reduced, and thus the base may have a reduced fore and aft dimension.

The swing cylinder may be placed to extend at an angle to a fore and aft direction of the tractor body. Then, the swing cylinder occupies a reduced fore and aft length, thereby reducing the fore and aft dimension of the base. This contributes toward a reduction in the load of the backhoe unit applied to the tractor body.

The swing cylinder is subjected to a heavy load. It is therefore preferable to support the swing cylinder by a strong portion of the base. As a specific measure therefor, it is proposed here that the engaging portions include a pair of right and left upper engaging portions and a lower engaging portion, the first cylinder connecting portion being disposed in a region substantially between the upper engaging portions and the lower engaging portion.

To achieve the above object, this invention proposes to limit an angle of swinging of the boom bracket by the swing cylinder to be smaller than 90 degrees. This is based on breaking of the fixed idea that the boom assembly must be horizontally swung 90 degrees right and left to transport soil, stone and the like with the bucket of the boom assembly. That is, by reducing the swing angle, a reduction is achieved in the distance between the vertical swing axis and backhoe mounting unit. It is extremely rate to swing the boom assembly 90 degrees to the right or left. There is hardly any disadvantage in performing ordinary operations if the swing angle of the boom bracket is limited to be smaller than 90 degrees. A simple form for limiting the swing angle reliably may be a pair of right and left stoppers disposed on the backhoe mounting frame for contacting the boom bracket. These stoppers may be disposed on the backhoe mounting frame.

The boom approaches the control column when the boom assembly is swung upward. In a preferred embodiment of this invention, the control column has a casing defining an opening in a lower rear portion thereof for permitting entry of an arm cylinder support of the boom assembly when the boom assembly swings upward by a maximum angle. This construction further reduces the fore and aft dimension from the control column to the vertical swing axis, and hence the fore and aft length of the backhoe unit.

As another measure for reducing the fore and aft dimension from the control column to the vertical swing axis, it is proposed that the distance from a rear surface of the casing to the vertical swing axis is smaller than a half of a maximum width of the boom assembly. The fore and aft dimension from the control column to the vertical swing axis may be reduced also where the footrest includes right and left portions located adjacent rear ends of right and left rear wheel fenders of the tractor, and a middle portion projecting forwardly of the rear ends of the right and left rear wheel fenders.

In a preferred embodiment of this invention, the engaging portions include a pair of right and left upper engaging portions and a lower engaging portion, and each of the upper engaging portions includes a pair of upper and lower mount holders vertically pivotably supported by pivotal supports to be forwardly openable and closable for approaching, from behind, an upper coupling attached to the backhoe mounting frame, and removably engaging the upper coupling from radially outward directions, and a retaining member movable, from behind, into a space between the mount holders and rearwardly of the pivotal supports for locking the mount holders against pivotal movement, the upper and lower mount holders being formed asymmetrical and the retaining member being inclined rearward and downward, thereby allowing the retaining member to extend under the footrest. This construction allows the footrest to be disposed close to the rear end of the tractor and to have an increased area.

The boom bracket may have a lower end thereof substantially level with the engaging portions. Thus, the base may be disposed in the lowest possible level to stabilize the weight balance of the backhoe unit.

To fulfill the foregoing object of this invention, it is also proposed that a walkthrough space is formed on the footrest to extend obliquely rearward from a rear position of the driver's seat.

Though a sufficient walkthrough space is formed for the driver, this construction reduces the fore and aft dimension from the rear end of the tractor body to the control column, contributing to making the base of the backhoe unit compact.

Further, the control column may have a casing with a front surface thereof smaller in width than a rear surface, and right and left sides inclined rearwardly and outwardly from the front surface. Thus, the fore and aft dimension from the rear end of the tractor body to the control column may be reduced while securing the large walkthrough space.

In one preferred embodiment of this invention, the footrest includes a pair of right and left foot supports diverging rearward for the driver's feet to be placed at opposite sides of the control column, and a passage portion extending between heel ends of the foot supports forwardly of the control column for enabling movement of the driver's feet. With this construction also, the fore and aft dimension from the rear end of the tractor body to the control column may be reduced while securing a sufficient space for the driver.

The footrest may include foot stoppers formed laterally of front edges thereof. Then, a projection of the feet from the footrest may be restricted even though the fore and aft dimension from the rear end of the tractor to the control column is reduced.

It is also advantageous to employ a construction in which the footrest is approximately channel-shaped opening rearward in plan view, the control column being trapezoidal, diverging rearward in plan view, and being disposed in a rearwardly opening portion of the footrest.

Further, the casing of the control column may house control valves for controlling the swing cylinder and the boom assembly, the control valves being operable by control levers arranged above the control valves. Then a free space is provided outside the control column, and no obstructive components are present around the driver's feet.

Other features and advantages of this invention will be apparent from the following description of the embodiment to be taken with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of a tractor having a backhoe unit according to this invention;

FIG. 2 is a plan view showing a framework of the tractor;

FIG. 3 is a partly exploded side view showing the framework of the tractor;

FIG. 4 is a side view of a principal portion showing the rear of the tractor and the backhoe unit;

FIG. 5 is a side view with a backhoe mounting frame and the front of the backhoe unit separate

FIG. 6 is a side view of the backhoe mounting frame and the front of the backhoe unit in a disconnected state;

FIG. 7 is a plan view of the backhoe mounting frame and the front of the backhoe unit in a connected state;

FIG. 8 is a rear view of the tractor with the backhoe mounting frame attached thereto;

FIG. 9 is a rear view of the backhoe mounting frame;

FIG. 10 is a rear view showing a rear vertical frame and lower links connected to the backhoe mounting frame;

FIG. 11 is a schematic side view showing the rear of the tractor and the backhoe unit;

FIG. 12 is a schematic plan view showing the rear of the tractor and the backhoe unit;

FIG. 13 is a schematic side view showing the backhoe unit and a base frame in a disconnected state;

FIG. 14 is a schematic side view showing the backhoe mounting frame and the base of the backhoe unit in a connected state;

FIG. 15 is a plan view, partly in section, of the lower links connected to a rear coupling frame; and

FIG. 16 is an exploded plan view of a lower link connecting structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of this invention will be described hereinafter with reference to the drawings.

FIGS. 1 through 14 show a tractor-front loader-backhoe (usually abbreviated as TLB) 1 . This TLB has a front loader F detachably attached to an intermediate position of a tractor body T to extend forward, and a backhoe unit B detachably attached to the rear of the tractor body T through a backhoe mounting unit 2 to act as a rear working implement. A midmount mower M may be attached under an intermediate portion of the tractor body T.

As shown in FIGS. 1 through 4 , the tractor body T includes an elongate vehicle body frame T 1 extending in the fore and aft direction, with an engine T 2 and a transmission case T 3 attached thereto as separated from each other in the fore and aft direction, to constitute a main vehicle body T 4 . Front wheels T 5 are attached to a front axle case T 6 supported in a forward position of the vehicle body frame T 1 . Rear wheels T 7 are attached to rear axle cases T 8 projecting right and left from the transmission case T 3 .

A hydraulic device T 10 is mounted on the transmission case T 3 for raising and lowering the working implement. Above the hydraulic device T 10 are a fuel tank T 9 and a driver's seat device 4 for reversing a driver's seat 3 between a forward facing position and rearward facing position. A floor seat T 11 extends from below the driver's seat 3 to a control portion T 14 so as to cover upper areas of the main vehicle body T 4 and fuel tank T 9 . Fenders T 12 of the rear wheels T 7 are attached by welding or by bolts to right and left sides of the floor seat T 11 .

T 13 denotes a hood for covering the engine T 2 , and the control portion T 14 is disposed rearwardly of the hood T 13 . A protector T 15 is disposed at the front end of the vehicle body frame T 1 for protecting the hood T 13 .

The vehicle body frame T 1 , broadly, includes a main frame T 17 , right and left mast support frames T 18 , and right and left reinforcing frames T 19 .

The main frame T 17 has an approximately rectangular shape in plan view, including a pair of right and left elongate plates T 17 a directly attached to the engine T 2 and transmission case T 3 arranged in between, and a plurality of cross members T 17 b formed of rods or plates arranged in the fore and aft direction and interconnecting the right and left elongate plates T 17 a.

The main frame T 17 has a support portion T 21 in a lower forward position thereof for supporting the front axle case T 6 to be pivotable about a center pin. The main frame T 17 has also a mounting portion from an intermediate position to a rearward position thereof for vertically movably supporting the midmount mower M.

Each of the right and left mast support frames T 18 has a side projecting member T 18 a fixed to and projecting outwardly from a longitudinally intermediate position of the main frame T 17 , and a mast support member T 18 b erected on an upper surface of an outer end of the projecting member T 18 a . The projecting member T 18 a is attached through a mounting element removably bolted to an outer surface of the main frame T 17 .

Each of the right and left reinforcing frames T 19 has two band plates T 19 a and T 19 b staggered relative to each other in the fore and aft and joined together in intermediate overlapping portions. The forward band plate T 19 a is connected at a forward end thereof to a bracket T 19 c fixed to the side projecting member T 18 a . The rearward band plate T 19 b is connected in a rearward portion thereof to the outer surface of the main frame T 17 by connecting elements such as bolts. The rear portion of the rearward band plate T 19 b is opposed to the elongate plates T 17 a with a space in between.

The reinforcing frames T 19 substantially overlap the main frame T 17 in side view. Thus, a load applied to the mast support members T 18 b may be distributed also to the rear of the main frame T 17 .

Numerals 6 and 7 denote front and rear mounting devices for interconnecting the right and left elongate plates T 17 a , as do the cross members T 17 b , and adjusting a spacing between the elongate plates T 17 a . The mounting devices 6 and 7 also serve to attach the transmission case T 3 to the main frame T 17 .

The front mounting device 6 has a pair of left and right mounts 6 L and 6 R which are L-shaped in front view. The vertical portion of each mount 6 L or 6 R is bolted to an inner surface of the elongate plate T 17 a , and bolted to the transmission case T 3 . The horizontal portions of the mounts 6 L and 6 R are connected to each other, with a length of connection fine-adjustable to match the spacing between the right and left elongate plates T 17 a . The lower portions (horizontal portions) of the mounts 6 L and 6 R project below the main frame T 17 to protect a lower front portion of the transmission case T 3 .

The rear mounting device 7 has a pair of left and right mounts 7 L and 7 R as does the front mounting device 6 . The vertical portion of each mount 7 L or 7 R is connected to the elongate plate T 17 a and the transmission case T 3 . The horizontal portions are connected to each other to match the spacing between the right and left elongate plates T 17 a.

The tractor body T has a frame structure, and the backhoe mounting unit 2 is connected to the body frame T 1 , transmission case T 3 and hydraulic device T 10 . Thus, the tractor body T may be regarded as including the backhoe mounting unit 2 .

The front loader F includes right and left masts F 1 , and a boom F 2 vertically pivotably supported at a proximal end thereof by upper ends of the masts F 1 . The boom F 2 supports a bucket F 3 at the distal end thereof to be pivotable in scooping and dumping action. The boom F 2 is hydraulically driven by a boom cylinder F 4 . The bucket F 3 is hydraulically driven by a bucket cylinder F 5 .

The masts F 1 fit downward into the mast support members T 18 b of mast support frames T 18 , with the lower ends thereof engaged with the mast support members T 18 b . The masts F 1 are locked in intermediate positions thereof by lock pins F 6 .

When unused, the front loader F may be detached from the mast support frames T 18 by pulling out the lock pins F 6 . When the tractor engages only in backhoe or mowing operations over a long period of time, the vehicle frame T 1 may have the right and left mast support frames T 18 and reinforcing frames T 19 detached from the main frame T 17 .

The midmount mower M is vertically movably attached to a lower portion of the main vehicle body T 4 through a suspending device M 1 . The mower M has blades rotatable by drive transmitted from the transmission case T 3 .

When the tractor engages in a loader and/or backhoe operation, the midmount mower M may be detached along with the suspending device M 1 from the tractor body T.

Referring to FIGS. 1-4 , 7 and 11 - 14 , the backhoe unit B has a pair of right and left connecting jaws B 2 arranged at the forward end of a base B 1 , and a boom bracket B 3 is pivotally supported by the rear of the base B 1 to be swingable about a vertical swing axis B 12 . A control column B 4 is mounted on the base B 1 . The base B 1 has hydraulically driven outriggers (stabilizers) T 16 at the right and left sides thereof.

The boom bracket B 3 is horizontally swingable right and left by a single swing cylinder B 5 . A boom assembly is attached to the boom bracket B 3 . That is, the boom bracket B 3 pivotally supports proximal ends of a boom B 6 and a boom cylinder B 7 , the boom B 6 being vertically swingable by the boom cylinder B 7 . The boom B 6 pivotally supports an arm B 8 at a distal end thereto to be vertically swingable by an arm cylinder B 9 . The arm B 8 pivotally supports a bucket B 10 at distal end thereof swingable by a bucket cylinder B 11 to take scooping and dumping action.

The boom B 6 is pivotally connected at the proximal end thereof to a lower rear end of the boom bracket B 3 through a pin B 6 b , with the boom cylinder B 7 mounted in the boom B 6 . The boom B 6 has an intermediate portion projecting upward to define an arm cylinder support B 6 a for pivotally supporting a proximal end of the arm cylinder B 9 .

When the boom B 6 is raised to an uppermost position by the boom cylinder B 7 , as shown in FIG. 1 , the boom B 6 assumes a substantially upright posture. In this state, the arm cylinder support B 6 a is located directly over the vertical swing axis B 12 and forwardly of the proximal end of the boom B 6 .

The base B 1 has a hollow construction with two flat plates B 1 a and B 1 b vertically spaced from each other and connected together through plates B 16 b and B 16 c constituting attaching mounts T 16 a of the outriggers T 16 , and the pair of right and left connecting jaws B 2 . The vertical swing axis B 12 is supported by a pair of upper and lower bearings B 1 c , and is vertically divided into two parts arranged coaxially.

Thus, the boom bracket B 3 has a forked bearing portion B 3 a . A flange B 3 b projects laterally of a vertically intermediate position of the boom bracket B 3 to act as a second cylinder connecting portion for connecting a forward end of a cylinder rod B 5 a of the swing cylinder B 5 .

A first cylinder connecting portion B 19 a for pivotally connecting a proximal end of the swing cylinder B 5 with a pin B 5 b is disposed in one lateral position, e.g. at the right side position in this embodiment, of the base B 1 , and adjacent and between the mount T 16 a of the right outrigger T 16 and the right connecting jaw B 2 .

That is, the first cylinder connecting portion B 19 a is secured to the plate B 16 c and connecting jaw B 2 between the upper and lower flat plates B 1 a and B 1 b constituting the base B 1 .

The swing cylinder B 5 is the clevis type that singly swings the boom bracket B 3 through a necessary angle right and left. The swing cylinder B 5 provides a swing angle smaller than 90 degrees, and requires only two hydraulic hoses to be connected thereto. The hoses are curved to a limited degree only to require a reduced space therefor.

The swing cylinder B 5 has the proximal end thereof disposed in one outer lateral position of the base B 1 , and the forward end of the cylinder rod B 5 a disposed centrally of the base B 1 . Thus, the swing cylinder B 5 is inclined with respect to the fore and aft direction. Compared with two swing cylinders the trunnion type extending fore and aft and parallel to each other, the swing cylinder B 5 may be arranged without being restricted by a middle space transversely of the base B 1 . On the contrary, the swing cylinder B 5 allows for a reduction in the fore and aft dimension of the base B 1 , to shorten the fore and aft dimension of the backhoe unit B. The backhoe unit B may therefore be close to the tractor body T.

Since the first cylinder mounting portion B 19 a of the swing cylinder B 5 is disposed adjacent right or left upper and lower engaging portions B 14 and B 15 , adjacent the mount B 16 a of the outrigger B 16 , or between the upper and lower engaging portions B 14 and B 15 and the mount B 16 a of the outrigger B 16 , the swing cylinder B 5 is supported in the strongest position inside the base B 1 .

Referring to FIGS. 4 , 7 , 11 and 12 , the boom bracket B 3 is swingable by the single swing cylinder B 5 right and left by a maximum swing angle S smaller than 90 degrees from a straight rearward posture (with the boom assembly extending rearward along a centerline of the vehicle body as shown in solid lines in FIGS. 7 and 12 ).

With the maximum right and left swing angle S of the swing cylinder B 5 set smaller than 90 degrees, when the boom B 6 is raised by a maximum angle to an uppermost position, a side surface of the arm cylinder support B 6 a which is the foremost portion of the boom B 6 does not move to a large extent forwardly of the vertical swing axis B 12 (as shown in two-dot chain lines in FIG. 12 ). Thus, to bring the side surface of the arm cylinder support B 6 a close to the rear of the control column B 4 , the position of the vertical swing axis B 12 may be shifted, by designing, further forward than in the prior art, thereby reducing a fore and aft dimension from the control column B 4 to the vertical swing axis B 12 , and hence the fore and aft length of the backhoe.

The maximum swing angle S, preferably, is in the order of 75 degrees. The control column B 4 has a casing B 4 a defining an opening B 4 b in a lower rear portion thereof for permitting entry of the arm cylinder support B 6 a when the boom B 6 swings by the maximum angle. The opening B 4 b also provides a passage for hydraulic pipes connected to control valves in the control column B 4 .

The boom B 6 supporting the arm cylinder B 9 has bearings projecting from a pair of right and left side plates and supporting a pivot pin of the arm cylinder B 9 , thereby having a maximum width L 2 of considerable size. Where the boom bracket B 3 is swingable by 90 degrees about the vertical swing axis B 12 , the distance L 1 from the rear surface of the casing B 4 a of the control column B 4 to the vertical swing axis B 12 must be greater than a half of the maximum width L 2 of the boom B 6 . However, by setting the maximum swing angle of the boom bracket B 3 smaller than 90 degrees as noted above, the bearings of the arm cylinder support B 6 a is further away from the rear surface of the casing B 4 a . The control column B 4 may be brought close to the vertical swing axis B 12 by a corresponding amount. Thus, the distance L 1 is set smaller than a half of the maximum width L 2 of the boom B 6 .

As noted above, the maximum swing angle S of the boom B 6 is dependent on the width of the arm cylinder support B 6 a of the boom B 6 , amount of projection of the bearings, and the presence of the opening B 4 b . The maximum swing angle S may be set to 80-85 degrees or thereabouts by minimizing the width of arm cylinder support B 6 a , minimizing the amount of projection of the bearings, and forming the opening B 4 b.

The fore and aft length of the backhoe may be reduced by placing the vertical swing axis B 12 closer to the control column post B 4 than in the prior art.

The backhoe mounting unit 2 includes a pair of right and left stoppers B 25 in rear positions thereof for contacting the boom bracket B 3 swung by the maximum angle S. The stoppers B 25 are formed of an elastic material such as rubber for reliably avoiding collision of the swinging boom B 6 with the control column B 4 .

In FIG. 11 , angle P represents a bottom-up angle. With this angle, the lower portion of the backhoe unit B does not contact the ground when the main tractor body T is placed on a footplate set to a truck deck for transporting the tractor-front loader-backhoe 1 .

Since the bottom-up angle P is substantially fixed, the smaller the distance is from the rear wheels T 7 to the rear end of the boom bracket B 3 , the lower the base B 1 and boom bracket B 3 may be located. Thus, by reducing the distance L 1 , the base B 1 may be located as low as possible to stabilize the weight balance of the backhoe unit B.

The base B 1 has a footrest B 24 attached to the upper surface thereof through support ribs B 23 . The control column B 4 is mounted on or alongside the footrest B 24 . A walkthrough space H is formed on the footrest B 24 to extend obliquely rearward from the rear of driver's seat 3 facing rearward. It is to be noted that the fore and aft direction herein is based on the fore and aft direction of the tractor.

The control column B 4 contains, in the casing B 4 a , a control valve C 1 for controlling the swing cylinder B 5 , a control valve C 2 for controlling the boom cylinder B 7 , a control valve C 3 for controlling the arm cylinder B 9 , a control valve C 4 for controlling the bucket cylinder B 11 , and control valves C 5 for controlling a pair of right and left outrigger cylinders.

These control valves C 1 -C 5 are mounted on an inner surface of a front wall of the casing B 4 a as arranged transversely of the tractor body. A swing and boom control lever C 6 , an arm and bucket control lever C 7 and right and left outrigger control levers C 8 are arranged above these valves through pivotal supports C 9 and C 10 . The pivotal supports C 9 and C 10 of the control levers C 6 -C 8 do not protrude forward from the casing B 4 a to be obstacles in the walkthrough space H.

As shown in FIGS. 7 and 12 , the casing B 4 a is trapezoidal, diverging rearward in plan view, with the front surface smaller in width than the rear surface, and the right and left sides inclined rearwardly and outwardly from the front surface. The front surface has dimensions necessary for attaching the control valves C 1 -C 5 , while the rear surface has sufficient dimensions for pipe connections, with a minimum fore and aft size.

The footrest B 24 is approximately channel-shaped opening rearward in plan view. The footrest B 24 includes a pair of right and left foot supports B 24 a diverging rearward for the driver to place his or her feet at opposite sides of the control column B 4 , and a passage portion B 24 b extending between heel ends of the foot supports B 24 a forwardly of the control column B 4 for enabling movement of the driver's feet.

The footrest B 24 includes foot stoppers B 24 c erected at front edges, rear edges and right and left side edges, or at least laterally of the front edges, to restrict the driver's feet projecting from the footrest B 24 .

The front of footrest B 24 has right and left sides, as seen in the fore and aft direction, lying adjacent rear ends of the right and left rear wheel fenders T 12 , and a middle portion projecting forwardly of the rear ends of right and left rear wheel fenders T 12 . The forward end of this middle portion is in substantially the same position, with respect to the fore and aft direction, as the rear end of a seating portion 3 A of driver's seat 3 ( 3 B denoting a backrest at the forward end.

The footrest B 24 has an upper surface area determined for securing an adequate accommodating space after an adequate distance is secured from the driver's seat 3 to the control column B 4 . With the right and left sides of the casing B 4 a inclined rearwardly and outwardly, the driver may comfortably place his or her feet wider apart at the tip than at the heel on the footrest B 24 . The walkthrough space H may allow movement of the driver despite small fore and aft and sideways distances from the casing B 4 a to the rear ends of right and left rear wheel fenders T 12 , by increasing the distance from the right and left sides of casing B 4 a to the rear ends of right and left rear wheel fenders T 12 .

Further, the rear end of the seating portion 3 A of driver's seat 3 facing rearward is, with respect to the fore and aft direction, located in substantially the same position as the backhoe mounting unit 2 or rearwardly of the rear end of the tractor body T. This feature also reduces the distance from the tractor body T to the footrest B 24 , the distance to the control column B 4 , and the distance to the base B 1 , thereby reducing the fore and aft length of the backhoe unit B.

The rear end of tractor body T and the forward end of the backhoe mounting unit 2 are adjacent each other in the fore and aft direction. The rear end of the seating portion 3 A also is adjacent to the rear end of tractor body T and the forward end of the backhoe mounting unit 2 . Thus, the fore and aft dimension from the tractor body T to the control column B 4 is reduced to make the base B 1 compact in the fore and aft direction.

Each of the right and left connecting jaws B 2 of the backhoe unit B has upper and lower engaging portions B 14 and B 15 . The upper and lower engaging portions B 14 and B 15 are detachably connected to upper and lower couplings 11 and 12 at one side of the backhoe mounting unit 2 . Thus, the backhoe unit B may be detachably attached to the tractor body T.

In FIGS. 1 through 14 , each upper coupling 11 of the backhoe mounting unit 2 has a pin 11 a . The upper engaging portion B 14 of each connecting jaw B 2 has a recess B 14 a opening forward for fitting on the pin 11 a (while avoiding interference), and a mounting device B 20 for gripping the pin 11 a fitted in the recess B 14 a.

The mounting device B 20 includes a pair of upper and lower mount holders B 20 b pivotally supported in upper positions of connecting jaw B 2 through upper and lower pins (pivotal supports) B 20 a , a spring B 20 c for biasing the mount holders B 20 b to an open position, and a retaining member B 20 d for retaining the upper and lower holders B 20 b in a closed position. The mount holders B 20 b define grip portions B 20 e for gripping the pin 11 a.

The retaining member B 20 d includes a rod supported to be slidable fore and aft by a bracket B 26 attached to the connecting jaw B 2 , and a head formed at a forward end of the rod. A spring B 20 f is mounted on the rod between the head and the bracket B 26 for constantly biasing the head forwardly.

The connecting jaw B 2 pivotably supports a lock release lever B 27 defining a slot B 28 receiving a pin B 29 projecting from the head of the retaining member B 20 d . By pivoting this lock release lever B 27 fore and aft, the retaining member B 20 d is moved in the fore and aft direction.

The head of the retaining member B 20 d is movable forward between the pair of mount holders B 20 b when the front ends of the mount holder B 20 b are closed, to maintain this closed state.

The retaining member B 20 d is disposed as inclined rearward and downward so that the rear end of the rod lies in a low position. Thus, the pair of mount holders B 20 b are formed vertically asymmetrical.

The retaining member B 20 d inclined downward may extend under the footrest B 24 , thereby allowing the footrest B 24 to be located close to the tractor body T. As a result, the fore and aft dimension of the base B 1 may be reduced.

Each of the upper and lower mount holders B 20 b has a rear end defining a curved surface B 30 about the pivotal support B 20 a acting as the center of curvature. When the front ends thereof are opened, the curved surfaces 58 of both mount holders B 20 b simultaneously contact the head of the retaining member B 20 d.

Each lower coupling 12 of the backhoe mounting unit 2 has a recess 12 a opening upward. The lower engaging portions B 15 of the connecting jaws B 2 share an elongate rod B 15 a extending transversely of the tractor body. The rod B 15 a placed in the recesses 12 a from above and supported therein.

In FIG. 14 , the upper couplings 11 of backhoe mounting unit 2 may be directly over the lower couplings 12 , but are disposed forwardly of the lower coupling 12 by a length L 3 . This shortens the distance from the tractor body T to the control column B 4 to further reduce the fore and aft length of the backhoe unit B.

When attaching the backhoe unit B to the tractor body T, the base B 1 is slightly tilted rearward, and the tractor body T is moved to place the recesses 12 a of the couplings 12 below the rod B 15 a of the lower engaging portion B 15 of the connecting jaw B 2 . Thereafter, the outriggers B 16 are operated to place the base B 1 in horizontal posture, and the rod B 15 a is inserted into the recesses 12 a.

As each mounting device B 20 approaches the pin 11 a , with the rod B 15 a resting in the recesses 12 a , inner parts of the grip portions B 20 e of mount holders B 20 b contact the pin 11 a . As a result, the upper and lower mount holders B 20 b are closed against the force of spring B 20 c.

When the upper and lower mount holders B 20 b are closed and the grip portions B 20 e fit on the pin 11 a , the spring B 20 f forces the retaining member B 20 d to enter between the upper and lower mount holders B 20 b . The pin 11 a is thereby maintained in the gripped state.

Each retaining member B 20 d is biased to the mount holders B 20 b by the spring B 20 f . By removing the retaining member B 20 d from the mount holders B 20 b against the force of spring B 20 f , the mounting device B 20 is opened to render the backhoe unit B detachable from the tractor body T.

The backhoe mounting unit 2 is connected in a vertically intermediate position thereof to the main frame T 17 , and in an upper intermediate position to the hydraulic device T 10 . A vertical rear frame 13 is mounted on the upper end of the backhoe mounting unit 2 . The backhoe mounting unit 2 has a hitch coupling 14 disposed at the lower end thereof. The backhoe mounting unit 2 is detachably attached to the rear end of the vehicle frame T 1 and upstanding so as to surround the rear of the transmission case T 3 .

The backhoe mounting unit 2 not only has the functions to attach the backhoe unit B and vertical rear frame 13 , but is constructed to attach, as a rear working implement, a raking device, a box blade device, a rotary plow, a soil packing device or a trailer. One of these devices may be used alone, or in combination with the front loader F and the midmount mower M attached to the tractor body T to carry out varied operations.

Referring to FIGS. 5 through 10 , the backhoe mounting unit 2 includes a pair of right and left vertical members 2 A, an upper member 2 B interconnecting upper positions of the right and left vertical members 2 A, and a lower member 2 C interconnecting lower positions of the right and left vertical members 2 A.

Each of the right and left vertical members 2 A is formed of a lower member 2 Aa and an upper member 2 Ab fixed together. The lower member 2 Aa has bent upper portion and lower portion extending horizontally in opposite directions. The upper member 2 Ab also has bent upper portion and lower portion extending horizontally in opposite directions.

As seen from FIGS. 15 and 16 , outer surfaces of the lower members 2 Aa of the vertical members 2 A have the elongate plates T 17 a of main frame T 17 fixed to vertically intermediate positions thereof, components of the upper couplings 11 fixed to upper positions, and components of the lower couplings 12 fixed to lower positions.

The lower member 2 C is bolted to lower horizontal portions of the right and left lower members 2 Aa. The lower member 2 C may be formed simply of plate, but the hitch coupling 14 is used in the embodiment. The hitch coupling 14 has a hitch joint 14 a providing a hitch connection point for connecting a traction rod of a soil packing device, trailer or the like.

The right and left vertical members 2 A have lower link pins 16 L and 16 R disposed in lower positions thereof. Both lower link pins 16 L and 16 R have flanges 16 a welded thereto. These flanges 16 a are bolted to inner surfaces of the vertical members 2 A.

The right and left lower link pins 16 L and 16 R are inwardly opposed to each other with a spacing 21 therebetween for receiving lower links 17 . The right lower link pin 16 R (or the left lower link pin 16 L) extends to the other side (left side) beyond a middle point transversely of the tractor body T.

Numeral 18 denotes a check chain connector extending over the right and left lower link pins 16 and attached to the right lower link pin 16 R by a set pin 18 a at a substantially middle point transversely of the tractor body T. The check chain connector 18 is attachable and detachable only by inserting and removing the set pin 18 a.

The check chain connector 18 is used to engage a forward end of a check chain extending between the right and left lower links 17 , and to restrict sideways movement of the right and left lower links 17 having forward ends thereof engaged with the right and left lower link pins 16 . This dispenses with special lower link retaining members.

That is, a portion of the check chain connector 18 that engages the lower link pins 16 has such a width that substantially fills a space between the right and left lower links 17 engaged with the right and left lower link pins 16 . The right and left lower links 17 may be removed from the spacing (gap) 21 only by detaching the check chain connector 18 .

The upper member 2 B is connected to the upper members 2 Ab of the vertical members 2 A through brackets. The upper member 2 B has a top link bracket 15 secured thereto for pivotally supporting a top link 24 through a pin.

The top link bracket 15 has an attaching portion 15 a formed of a plate material and defining a link connector 15 b projecting rearward. The attaching portion 15 a is fixed in an upper position thereof to the upper member 2 B, and bolted at the lower end to the hydraulic device T 10 .

A lower base plate 13 A of the vertical rear frame 13 is bolted to upper horizontal portions of the upper members 2 Ab of the vertical members 2 A. The vertical rear frame 13 has a main frame body 13 B formed of a pipe bent into an inverted U-shape and fixed at opposite lower ends thereof to the lower base plate 13 A, and a lower member 13 C connected to the opposite lower ends of the main frame body 13 B and mounted on the lower base plate 13 A.

The lower base plate 13 A reinforces the upper portion of the backhoe mounting unit 2 , while the upper member 2 B reinforces the lower portion of the vertical rear frame 13 .

The U-shaped main frame body 13 B has right and left props 13 a erected on the lower base plate 13 A. The right and left props 13 a are wide apart in intermediate to upper portions thereof. Thus, the main frame body 13 B bulges laterally outwardly in the intermediate to upper portions thereof. Even where the driver's seat 3 overlaps the vertical rear frame 13 in the fore and aft direction, an accommodating space is secured for the driver seated on the driver's seat 3 .

The vertical rear frame 13 includes flex portions 13 C formed in intermediate positions of the main frame body 13 B. Thus, the vertical rear frame 13 may be bent forward or rearward to reduce the height of the main frame body 13 B for storage or other purposes.

As shown in FIG. 8 , a pair of right and left attachment reinforcing members 23 interconnect the right and left vertical members 2 A and the hydraulic device T 10 , to improve mounting strength of the backhoe mounting unit 2 attached to the tractor body T.

Numeral 25 is a PTO shaft projecting rearward from the transmission case T 3 and overlapping the backhoe mounting unit 2 in the fore and aft direction.

This invention is not limited to the above embodiment, but may be modified in various ways. For example, the first cylinder mounting portion B 19 a of the swing cylinder B 5 may be disposed at the left side of the base B 1 , or adjacent and rearwardly of the mount B 16 a of one outrigger B 16 .

Claims

1. A backhoe unit detachably attached to a backhoe mounting frame disposed on a tractor body rearwardly of a driver's seat, comprising:a base having engaging portions for connection to said backhoe mounting frame; a driver's footrest and a control column disposed on said base; a vertical swing axis supported by said base; a boom bracket supported to be swingable about said vertical swing axis; a boom assembly attached to said boom bracket; and a single swing cylinder having one end thereof connected to said base through a first cylinder connecting portion, and the other end connected to said boom bracket through a second cylinder connecting portion, to swing said boom bracket horizontally, said swing cylinder disposed in one lateral side of said base to be offset from a centerline of said tractor body and extends slantwise in plan view relative to the centerline.

2. The backhoe unit as defined in claim 1, wherein said engaging portions include a pair of right and left upper engaging portions and a lower engaging portion, said first cylinder connecting portion being disposed in a region substantially between said upper engaging portions and said lower engaging portion.

3. The backhoe unit as defined in claim 1, further comprising swing angle limiting means for limiting a maximum angle of swinging of said boom bracket by said swing cylinder to be less than 90 degrees from a longitudinal axis extending through said vertical swing axis to each of a right side and a left side.

4. A backhoe unit detachably attached to a backhoe mounting frame disposed on a tractor body rearwardly of a driver's seat, comprising:a base having engaging portions for connection to said backhoe mounting frame; a driver's footrest and a control column disposed on said base; a vertical swing axis supported by said base; a boom bracket supported to be swingable about said vertical swing axis, and; a boom assembly attached to said boom bracket; a single swing cylinder having one end thereof connected to said base through a first cylinder connecting portion, and the other end connected to said boom bracket through a second cylinder connecting portion, to swing said boom bracket horizontally, wherein said swing cylinder is disposed in one lateral side of said base to be offset from a centerline of said tractor body and extends slantwise in plan view relative to the centerline; and swing angle limiting means for limiting a maximum angle of swinging of said boom bracket by said swing cylinder to be less than 90 degrees from a longitudinal axis extending through said vertical swing axis to each of a right side and a left side.

5. A The backhoe unit as defined in claim 4, wherein said swing angle limiting means is a pair of right and left stoppers disposed on said backhoe mounting frame for contacting said boom bracket to check the swinging of said boom bracket over the maximum angle.

6. The backhoe unit as defined in claim 4, wherein said control column has a casing defining an opening in a lower rear portion thereof for permitting entry of an arm cylinder support of said boom assembly when said boom assembly swings upward by a maximum angle.

7. The backhoe unit as defined in claim 4, wherein said control column has a casing, a distance from a rear surface of said casing to said vertical swing axis being smaller than a half of a maximum width of said boom assembly.

8. The backhoe unit as defined in claim 4, wherein:said engaging portions include a pair of right and left upper engaging portions and a lower engaging portion; and each of said upper engaging portions includes: a pair of upper and lower mount holders vertically pivotably supported by pivotal supports to be forwardly openable and closable for approaching, from behind, an upper coupling attached to said backhoe mounting frame, and removably engaging said upper coupling from radially outward directions, and a retaining member movable, from behind, into a space between said mount holders and rearwardly of said pivotal supports for locking said mount holders against pivotal movement, said upper and lower mount holders being formed asymmetrical and said retaining member being inclined rearward and downward, thereby allowing said retaining member to extend under said footrest.

9. The backhoe unit as defined in claim 4, wherein said boom bracket has a lower end thereof substantially level with said engaging portions.

10. The backhoe unit as defined in claim 4, wherein said footrest includes right and left portions located adjacent rear ends of right and left rear wheel fenders of the tractor, and a middle portion projecting forwardly of said rear ends of said right and left rear wheel fenders.

11. A backhoe unit detachably attached to a backhoe mounting frame disposed on a tractor body rearwardly of a driver's seat, comprising:a base having engaging portions for connection to said backhoe mounting frame; a control column disposed on said base; a vertical swing axis supported by said base; a boom bracket supported to be swingable about said vertical swing axis; a boom assembly attached to said boom bracket; a single swing cylinder having one end thereof connected to said base through a first cylinder connecting portion, and the other end connected to said boom bracket through a second cylinder connecting portion, to swing said boom bracket horizontally; and a driver's footrest disposed on said base, wherein said footrest is approximately channel-shaped opening rearward in plan view, said control column being in a form of a trapezoid having opposed lateral sides diverging rearward in plan view and being disposed in the rearwardly opening portion of said footrest, and the channel-shaped portion of said footrest defines a walkthrough space extending obliquely rearward from a rear position of said driver's seat for the driver to climb up and down from said footrest from lateral sides thereof.

12. The backhoe unit as defined in claim 11, wherein said control column has a casing with a front surface thereof smaller in width than a rear surface, and right and left sides inclined rearwardly and outwardly from said front surface.

13. The backhoe unit as defined in claim 11, wherein said footrest includes a pair of right and left foot supports diverging rearward for the driver's feet to be placed at opposite sides of said control column, and a passage portion extending between heel ends of said foot supports forwardly of said control column for enabling movement of the driver's feet.

14. The backhoe unit as defined in claim 11, wherein said footrest includes foot stoppers formed laterally of front edges thereof.

15. The backhoe unit as defined in claim 11, wherein said control column has a casing housing control valves for controlling said cylinder and said boom assembly, said control valves being operable by control levers arranged above said control valves.

16. The backhoe unit as defined in claim 11, wherein said swing cylinder is a single cylinder disposed in one lateral side of said base to be offset from a centerline of said tractor body and extends slantwise in plan view relative to the centerline.

17. The backhoe unit as defined in claim 11, further comprising swing angle limiting means for limiting a maximum angle of swinging of said boom bracket by said swing cylinder to less than 90 degrees from a longitudinal axis extending through said vertical swing axis to each of a right side and a left side.

18. The backhoe unit as defined in claim 17, wherein said swing angle limiting means is in the form of a pair of right and left stoppers disposed on said backhoe mounting frame for contacting said boom bracket to check the swinging of said boom bracket over the maximum angle.