JP2003304709A - Device for lifting implement of tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that a stroke and a capacity of an external cylinder are limited when a support to a mission case of the external cylinder and the fulcrum of a lower link of a three-point suspension are separately arranged in upper and lower positions, it is difficult to keep a balance of front and rear weight because of a long distance between an implement and a tractor when the support to the mission case of the external cylinder and the support of the lower link of the three-point suspension are separately arranged in front and rear and assembling parts and assembling labor are increased caused by installing brackets and pins to the mission case. <P>SOLUTION: In a tractor 100 in which the externally installed cylinders 2L, 2R are arranged on the side of a rear transmission case 4 and an implement- lifting device 1 moved by the external cylinders is installed, the fulcrum 2a of the external cylinder and the fulcrum of the lower link 13 for connecting the implement are arranged on the same shaft. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction of a working machine lifting device arranged at a rear portion of a body of a tractor.

[0002]

2. Description of the Related Art Conventionally, in a work vehicle such as a tractor, a working machine is mounted on a rear portion of a machine body through a working machine mounting device, and a hydraulic actuator such as a hydraulic cylinder is operated in the working machine mounting device. Therefore, a working machine lifting device for lifting the working machine is provided. The hydraulic actuator is composed of a hydraulic cylinder mounted inside a hydraulic cylinder case mounted on a transmission case or the like, and a piston rod of the hydraulic cylinder is interlocked with left and right lower links via a lift arm for lifting a working machine. Then, the working machine is moved up and down by expanding and contracting the hydraulic cylinder. Further, in the above-described work machine lifting device, the work machine is configured to be lifted and lowered by a single hydraulic cylinder, and therefore, when mounting a wide work machine or a heavy work machine, the work machine is not supported. The force and rigidity are insufficient to rotate up and down. Therefore, there is a technology for arranging two exterior hydraulic cylinders in the rear part of the machine body and interlockingly connecting them with the left and right lower links via lift arms, lift rods or hydraulic cylinders for horizontal control to rotate the working machine up and down. Proposed. For example, it is as in the technique of Japanese Patent Laid-Open No. 8-112006.

[0003]

However, JP-A-8-1
In the working machine lifting device of Japanese Patent Publication No. 12006, in order to avoid interference between a three-point support device (three-point link type working machine mounting device) for connecting the working machine to the rear of the tractor and the outer cylinder, the lower end of the outer cylinder The support point of the section is disposed above the tractor-side fulcrum of the lower link that constitutes the three-point support device. However, with such an arrangement, the distance between the two points (the middle part of the lift arm and the side surface of the mission case) that pivotally mount the exterior cylinder becomes small, which is a limitation in mounting a large capacity, large stroke exterior cylinder. . Also,
In order to mount a large capacity, large stroke exterior cylinder, there is also a method of moving the exterior cylinder pivot point on the side of the mission case downward and moving the tractor side fulcrum of the lower link to the rear of the mission case. However, such an arrangement increases the distance between the tractor and the working machine, which is not preferable from the viewpoint of the front-rear weight balance of the tractor when the working machine is connected. Further, in any of the above cases, a bracket or a pin for supporting the lower end of the lower link or the exterior cylinder must be provided in the mission case or the like, which increases the number of parts and the number of assembly steps.

[0004]

The problem to be solved by the present invention is as described above, and the means for solving this problem will be described below.

That is, according to the first aspect of the present invention, in a tractor in which an exterior cylinder is arranged on a side of a mission case and a working machine lifting device operated by the exterior cylinder is provided, a support point of the exterior cylinder and a working machine are provided. The fulcrum of the connecting lower link is arranged coaxially.

In the present invention, the supporting point of the exterior cylinder and the fulcrum of the lower link are rotatably supported by the same pin.

According to the third aspect of the present invention, the pin is supported by the mission case and the lower link check chain bracket.

According to another aspect of the present invention, the support point of the exterior cylinder is arranged at a position closer to the mission case than the pin support position of the check chain bracket, and is located farther from the mission case than the pin support position of the check chain bracket. The fulcrum of the lower link is arranged.

According to a fifth aspect of the present invention, the hydraulic valve of the working machine lifting device is arranged on one surface of the valve case, and the piping path between the hydraulic valves is provided on the other surface of the valve case.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. 1 is a left side view of a tractor, FIG. 2 is a left side view showing a first embodiment of a working machine lifting device of the present invention, and FIG. 3 is a rear view showing a first embodiment of a working machine lifting device of the present invention. 4 is a plan view showing a first embodiment of the working machine lifting device of the present invention, FIG. 5 is a perspective view of a check chain bracket, and FIG. 6 is a left side view showing a second embodiment of the working machine lifting device of the present invention. FIG. 7 is a partial left side sectional view of a hydraulic valve case according to an embodiment of the present invention, FIG. 8 is a plan view of a hydraulic valve case according to an embodiment of the present invention, and FIG. 9 is a conventional hydraulic valve. FIG. 10 is a plan view of the case, FIG. 10 is a plan view showing a piping path of the flow control swing valve, and FIG. 11 is a rear partial cross-sectional view showing a piping path of the flow control swing valve.

First, a tractor 100 having a working machine lifting device 1 which is a first embodiment of a working machine lifting device of the present invention will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, front wheels 102, 102 are supported by an engine frame 101 of a tractor 100 via a front axle case, and a rear mission case 4 is arranged at a rear portion of the engine frame 101 via a clutch housing. Rear axle cases 10 on both sides of the mission case 4
The rear wheels 103, 103 are supported via the. The working machine 120 can be mounted on the rear portion of the rear mission case 4 via a three-point supporting device (three-point link type working machine mounting apparatus) including the top link 50, the lower link 13, and the like. Further, a front wheel drive output shaft projects forward from the lower front portion of the rear mission case 4 so that the front wheels 102, 102 can be driven via a universal joint, a transmission shaft, or the like.

An engine 105 is mounted on the engine frame 101, and the engine 105 is covered with a bonnet 104. A dashboard 111 is arranged at the rear of the bonnet 104, and an operation panel 118 and a steering handle 119 are provided on the dashboard 11.
Is arranged, the seat 115 is arranged behind it, and the driving parts such as the dashboard 111 and the seat 115 are covered by the cabin 112. The cabin 112 is a cabin frame in which a front strut 113 is erected from the engine frame 101 via a support stay, a rear strut 114 is erected from the rear mission case 4, a beam is laid horizontally on the upper portion, and the ceiling is The roof 116 covers the front surface of the windshield, the side surfaces of the doors 117 and 117, and the rear surface of the rear glass.

As shown in FIGS. 2 to 4, the working machine lifting device 1 includes a pair of left and right exterior cylinders 2L and 2R (exterior cylinder 2R is not shown), a hydraulic valve case 3, and connecting these. It consists of hydraulic piping. Tractor 1
The hydraulic valve unit 3 is fixedly mounted on the upper surface of the rear transmission case 4 at 00 by bolting or the like.
The upper surface of the hydraulic valve case 3 is a valve arranging space 3a, and the rear part thereof is a lift arm pivoting portion 3b. By using the valve arrangement space 3a on the upper surface, it is possible to make the structure lower than that of the conventional cylinder case.
With the cabin specification, seats can be placed lower to increase the living space. Then, the lift arm pivotally connecting portion 3b
One end of a pair of left and right lift arms 5L and 5R (the lift arm 5R is not shown) is rotatably attached to the shaft. Details of the hydraulic valve case 3 will be described later. Since the exterior cylinders 2L and 2R have substantially the same configuration, the exterior cylinder 2L will be described below. Similarly, in the first embodiment, the left side of the tractor 100 will be described, and the right side of the tractor 100 will not be described as being substantially the same.
The exterior type cylinder 2L is composed of a cylinder case 2a, a case side pivoting portion 2b, a cylinder rod 2c, a rod side pivoting portion 2d and the like. A hydraulic pipe 6 is provided on the side surface of the cylinder case 2a.
One end of is connected. The other end of the hydraulic pipe 6 is connected to a lifting hydraulic valve fixedly mounted on the upper surface of the hydraulic valve unit 3, and the exterior cylinder 2L is configured to be expandable / contractible by switching the hydraulic valve. The exterior type cylinder 2
The rear transmission case 4 and the hydraulic valve unit 3 are located in the substantially left and right center between L and 2R, and the top link bracket 4 is provided on the rear surface of the hydraulic valve unit 3.
0 is fixed, and the front end of the top link 50 (shown in FIG. 1) can be mounted.
0 and the exterior cylinders 2L and 2R are arranged so as to overlap with each other, and the exterior cylinders 2L and 2R are arranged in front of the rear end of the top link bracket 40.
It is arranged so that the length in the front-rear direction becomes short. A PTO shaft 41 projects rearward from the rear surface of the rear transmission case 4 below the top link bracket 40.

Next, a method of fixing the exterior cylinder to the tractor, which is an essential part of the present invention, will be described. As shown in FIG. 3, a pin fixing bracket 7 is provided on the lower portion of the side surface of the rear mission case 4, and the pin fixing bracket 7 is provided.
The pin 8 is protruded from the tractor 100 toward the side. The case-side pivoting portion 2b of the exterior cylinder 2L is loosely fitted in the pin 8. On the other hand, the rod-side pivotal attachment portion 2d of the exterior cylinder 2L is pivotally attached by a pin 9 to a middle portion of the lift arm 5L so as to be rotatable. With this configuration, when the exterior cylinder 2L extends due to the operation of the lifting / lowering hydraulic valve, the lift arm 5L pivots upward, and the tip of the lift arm 5L and the middle of the lower link 13 of the three-point support device. The lower link 13 is rotated upward by the lift rod 16 (shown in FIG. 1) connected to the section, and the working machine is lifted upward. Further, check chain brackets 11 are fixedly mounted on the lower surface of the rear axle case 10 protruding leftward and rightward from the side of the rear mission case 4. The pin 8 is inserted into the pin support hole 11e of the check chain bracket 11, and the external cylinder 2L is rotatably supported so as to be sandwiched between the pin fixing bracket 7 and the check chain bracket 11.
In the present embodiment, the case-side pivoting portion 2b of the exterior cylinder 2L is pivotally attached to the pin 8, and the rod-side pivotal portion 2d of the exterior cylinder 2L is pivotally attached to the middle of the lift arm 5L. The rod side pivot portion 2d of the cylinder 2L has the pin 8
In addition, the same effect can be obtained even if the case side pivotal attachment portion 2b of the exterior cylinder 2L is pivotally attached to a middle portion of the lift arm 5L.

As shown in FIG. 5, the check chain bracket 11 mainly includes a base portion 11a and a first bracket 11.
b, a second bracket 11c, a reinforcing member 11d, and the like, which are structures combined by a method such as welding. A first bracket 11b and a reinforcing member 1 that extend downward and rearward from the lower surface of a base portion 11a in which the plate bodies are horizontally arranged.
1d is fixed by a method such as welding, and the base 11
A plurality of fixing bolt fixing holes 11g are formed in a, and are screwed to the lower surface of the rear axle case 10 by bolts or the like. However, the fixing method is not limited. In addition, a lower base portion of a safety frame or a cabin frame is fixedly provided on the upper surface of the rear axle case 10 which is vertically opposite to the mounting surface of the base portion 11a, and the left and right rear axle cases are connected to each other to reinforce the check chain bracket 11. The mounting rigidity is also increased. A check chain locking hole 11f is formed in the rear end of the first bracket 11b, and the front end of the check chain 12 is locked by a shackle or the like. One end of the second bracket 11c, which is substantially L-shaped in plan view, is fixedly attached to the side surface of the first bracket 11b in the front-rear midway portion, and a pin support hole 11e is provided at the rear end thereof, the pin support hole 11e and the check chain. Locking hole 11f and the pin fixing bracket 7
The center of the pin hole of is arranged on the same axis so that the check chain 12 and the lower link 13 can be smoothly rotated. The pin 8 is inserted through the pin support hole 11e, and the pin 8 is also inserted into the pin hole of the pin fixing bracket 7 and supported by both. Reinforcing member 11d
Connects the lower surface of the base 11a and the front surface of the second bracket 11c to enhance the rigidity of the check chain bracket 11.

The tip of the pin 8 inserted through the pin support hole 11e projects further outward from the tractor 100 than the pin support hole 11e. The lower link 13 of the three-point support device is rotatably pivotally attached to the projecting portion as shown in FIGS. 3 and 4. The rear end of the check chain 12 is locked in the middle of the lower link 13, the exterior cylinder 2L is arranged on the machine center side (inner side) of the lower link 13, and the check chain 12 is arranged outside the lower link 13. , A working machine 1 at the rear end of the lower link 13.
20 (shown in FIG. 1) are connected.

As described above, fixing the exterior cylinder 2L to the tractor has the following advantages. As described above, when the case-side pivotally connecting portion 2b and the front end portion, which is the fulcrum of the lower link 13 that connects the working machine, are vertically arranged on the side surface of the rear mission case 4 of the tractor 100, the stroke of the exterior cylinder 2L Also, there is a problem that it is difficult to increase the capacity. Further, when the case-side pivotally connecting portion 2b and the front end portion, which is the fulcrum of the lower link 13 that connects the working machine, are arranged front and rear on the side surface of the rear transmission case 4 of the tractor 100, the stroke and capacity of the exterior cylinder 2L are increased. However, the distance between the working machine and the tractor 100 becomes large, and it becomes difficult to maintain a good front-rear weight balance.

First, the case-side pivotally connecting portion 2b, which is a support point of the exterior cylinder 2L, and the front end portion, which is a fulcrum of the lower link 13 that connects the working machine, are located from the side surface of the rear mission case 4 of the tractor 100 from the tractor. By arranging on the same axis as the pin 8 projecting from the side of 100, it is possible to solve the above two problems.

Secondly, the case-side pivotally-attached portion 2b and the front end portion, which is a fulcrum of the lower link 13 for connecting the working machine, project from the side surface of the rear mission case 4 of the tractor 100 toward the tractor 100 side. It is pivotally attached to the same pin 8.
Therefore, it is not necessary to prepare separate pins, and the number of parts can be reduced. Further, the space required for pivotally connecting the exterior cylinder 2L and the lower link 13 can be reduced, which contributes to space saving.

Thirdly, the pin 8 is supported at two positions, that is, a pin fixing bracket 7 arranged on the side surface of the rear mission case 4 and a check chain bracket 11, and the exterior is provided at a portion sandwiched by the supporting points. Since the case-side pivotally-attached portion 2b, which is the support point of the cylinder 2L, is supported, the rigidity around the pin 8 is increased, and the operating force of the exterior cylinder 2L can be set to a larger value. Moreover, since a part of the check chain bracket 11 is used as a support point for the pin 8, there is an effect of reducing the number of parts.

Fourth, the check chain bracket 1
The case-side pivoting portion 2b, which is a support point of the exterior cylinder 2L, is arranged at a position closer to the rear mission case 4 than the position where 1 supports the pin 8, and the check chain bracket 11 is rearward from the position where the pin 8 is supported. Since the front end portion, which is the fulcrum of the lower link 13, is arranged at a position distant from the mission case 4 (that is, near the tip of the pin 8), it is easy to remove the lower link 13 from the tractor 100 (specifically, the pin). It is possible to easily remove the lower link 13 from the pin 8 by removing the retaining pin 14 locked in the through hole 8a penetrating the side surface near the tip of the pin 8).

The shape of the check chain bracket 11 is not limited to this embodiment. Further, the fixed position of the check chain bracket 11 is fixed to the rear axle case 10.
It is not limited to the lower surface, but may be the rear surface of the rear axle case 10 or the side surface of the rear mission case 4, for example. The means for preventing the lower link 13 from coming off from the pin 8 is not limited to the coming-off preventing pin 14, and for example, a groove may be provided on the peripheral surface near the tip of the pin 8 to fit a C ring or an E ring. May be.

The working machine lifting device 1 which is the first embodiment of the working machine lifting device of the present invention includes a pair of left and right exterior cylinders 2L and 2R. This has the following advantages in addition to increasing the lifting force of the working machine. That is, the hydraulic piping path is branched into two systems downstream of the lift arm raising valve (not shown) arranged in the valve arrangement space 3a on the upper surface of the hydraulic valve unit 3, and the hydraulic piping paths of these two systems are branched. A throttle valve and a relief valve are provided in each of the above, and then connected to the hydraulic pipes 6 of the exterior cylinders 2L and 2R. By configuring the hydraulic piping path in this way, it is possible to separately control the extension amounts of the exterior cylinders 2L and 2R. This means that the work implement lifting device 1 can also serve as a work implement horizontal holding mechanism for holding the posture of the work implement substantially horizontally with respect to the field even if the tractor 100 is tilted with respect to the field. This means that it is not necessary to separately provide a working machine horizontal holding mechanism. Therefore, it is possible to omit the parts related to the work implement horizontal holding mechanism. Further, on the side surfaces of the cylinder cases 2a of the exterior cylinders 2L and 2R, hydraulic pipes are connected to two places near the upper end and the lower end, and a switching valve is connected to the hydraulic pipes so that work can be performed even when the working machine descends. It is possible to positively generate a descending force by hydraulic pressure instead of descending only by the weight of the machine.

Next, a tractor having a working machine lifting device 15 which is a second embodiment of the working machine lifting device of the present invention will be described with reference to FIGS. 6 to 11. The working machine lifting device 15 according to the second embodiment includes lift cylinders 5L and 5R and exterior cylinders 2L and 2R for the rear mission case 4.
Although the mounting method is substantially the same as that of the working machine lifting device 1 of the first embodiment, the mechanism for horizontally holding the working machine is different. That is, the lift rod 16L connecting the lift arm 5L and the lower link 13
A tilting cylinder 17 is provided at a midway point. The two hydraulic pipes 18 a and 18 b connected to the upper and lower side surfaces of the tilt cylinder 17 are connected to an electromagnetic flow control swing valve (flow control swing valve) 19 arranged on the hydraulic valve case 3. . By operating the flow control swing valve 19, hydraulic piping 1
The direction of the hydraulic oil sent to 8a and 18b is switched, and the tilt cylinder 17 expands and contracts. As a result, the turning angles of the left and right lower links 13 can be changed, and the posture of the working machine can be maintained substantially horizontal to the field or at a desired inclination angle regardless of the posture of the tractor 100 main unit. Is possible. Further, in the second embodiment, it is not necessary to separately control the expansion and contraction amounts of the left and right exterior cylinders 2L and 2R as in the first embodiment. The throttle valve, etc.) can be omitted. Further, in the second embodiment, when the work machine is light in weight, the exterior cylinder 2 is used.
It is possible to omit either one of L and 2R and to raise the working machine by one exterior cylinder. In this case, the left and right lift arms are connected by a rotary shaft.

In the second embodiment, the exterior cylinder 2
A hydraulic lift valve 20 for expanding and contracting the L · 2R and a flow control swing valve 19 for expanding and contracting the tilting cylinder 17 are required. These hydraulic valves are arranged on the upper surface of the hydraulic valve case 3. As shown in FIGS. 7 and 8, the hydraulic valve case 3 has a box shape with a hollow inside and an open bottom surface. Further, the upper surface of the hydraulic valve case 3 has bolt holes 21, 21 ... For fastening to the upper surface of the rear transmission case 4 with bolts and the like, and the rear portion projects upward to rotate the lift arms 5L, 5R. A lift arm pivot portion 3b for movably pivoting is formed. Further, as shown in FIG. 7, the hydraulic valve case 3
A hydraulic lift valve 20 and a flow control swing valve 19 are attached to the upper surface. At this time, the hydraulic lift valve 20 and the flow control swing valve 19 also have a hydraulic oil port on the lower surface side in contact with the hydraulic valve case 3. Therefore, on the upper surface of the hydraulic valve case 3, oil holes (specifically, the oil holes 22, 23, 24, 2 in the hydraulic valve case 3 of the present embodiment are located.
5) is drilled. These oil holes penetrate to the lower surface of the hydraulic valve case 3, the oil hole 24 and the oil hole 25 are connected by a pipe 35, and the oil hole 22 and the oil hole 23 are connected by a pipe 36. The pipes 35 and 36 are configured to be housed in the hollow portion of the lower surface of the hydraulic valve case 3.

On the other hand, as shown in FIG. 9, in the conventional hydraulic valve case 26, the central portion 26a (hatched portion in FIG. 9) is formed of a thick member, and the lateral hole 27 is formed from the side wall of the central portion 26a.・ 28 ・ 29 ・ 30 are drilled. The horizontal hole 27 and the horizontal hole 28 are provided so as to communicate with each other, and the tip thereof also communicates with the oil holes 24 and 25 formed below the upper surface of the hydraulic valve case 26. Then, by closing the side wall of the central portion 26a with the plugs 31 and 32, the oil hole 2
An oil passage from 4 to the oil hole 25 is formed. Similarly,
The horizontal hole 29 and the horizontal hole 30 are provided so as to communicate with each other, and the tip thereof also communicates with the oil holes 22 and 23 formed from above. Then, by closing the side wall of the central portion 26a with the plugs 33 and 34, an oil passage from the oil hole 22 to the oil hole 23 is formed.

In the conventional hydraulic valve case 26, since the lateral holes 27, 28, 29 and 30 are bored from the side wall, the number of processing steps is large. Further, since the central portion 26a is a thick member, the weight is large. On the other hand, in the hydraulic valve case 3 according to the embodiment of the present invention, the horizontal holes are not bored, and the piping 35.
Since 6 is connected, processing is easy and the number of processing steps can be reduced. Further, the degree of freedom of piping is high, which is advantageous in design, and since the inside of the hydraulic valve case 3 does not need to be thick, the weight can be made lighter than that of the conventional hydraulic valve case 26.

Next, the connection method of the hydraulic piping path between the flow control swing valve 19 and the tilting cylinder 17 in the working machine lifting device 15 according to the second embodiment will be described with reference to FIGS.
0 and FIG. 11. Since the flow control swing valve 19 is of an electromagnetic type, solenoids are arranged on both left and right sides, and output oil passages are also arranged on both left and right sides. If the hydraulic pipes 18a and 18b are respectively connected to the output oil passages, the left and right sides are connected to the tilt cylinder cylinder 17 on the left and right sides, so that one of the pipe paths becomes long and complicated. Therefore, in the hydraulic valve case 3 which is one mode of the embodiment of the present invention, the left and right output oil passages are formed on the lower surface of the flow control swing valve 19, and the left and right other output oil passages are arranged on one side surface. A vertical hole 37 is formed in the main body side hydraulic valve case 3 at a portion corresponding to the output oil passage arranged on the lower surface side.
A lateral hole 38 is formed from the right side surface (other side) of the hydraulic valve case 3 so as to communicate therewith, and the hydraulic pipe 1 is provided at the outlet of the lateral hole 38.
By connecting 8b, flow control swing valve 1
The connection location was close to the hydraulic pipe 18a connected on the right side of 9. With this configuration, the hydraulic pipe 18
Since a and 18b have the same length, the parts can be made common, a simple hydraulic pipe path can be configured, and both pipes can be fixed at the same time.

[0029]

Since the present invention is constructed as described above,
The following effects are achieved.

That is, as described in claim 1, in a tractor in which an exterior cylinder is arranged on the side of a mission case, and a working machine lifting device operated by the exterior cylinder is provided, a support point of the exterior cylinder and a working machine are provided. Since the fulcrum of the lower link that connects the and the lower link is arranged on the same axis, a large stroke, large capacity exterior cylinder is installed, and the lower link support point is installed as far forward as possible to balance the front and rear weight of the tractor. It is possible to keep good.

Since the support point of the exterior cylinder and the fulcrum of the lower link are rotatably supported by the same pin, the pin for pivotally mounting the exterior cylinder and the lower link are provided. The number of parts can be reduced because it is not necessary to prepare each pin for pivotally attaching the. Further, the space required for pivotally connecting the exterior cylinder and the lower link can be reduced, which contributes to space saving.

Since the pin is supported by the mission case and the check chain bracket of the lower link as described in claim 3, it has a supporting structure to increase the rigidity around the pin and to increase the operating force of the exterior cylinder. It is possible to set. Further, since a part of the check chain bracket is used as a support point for the pin, there is an effect of reducing the number of parts.

According to a fourth aspect of the present invention, the support point of the exterior cylinder is arranged at a position closer to the mission case than the pin support position of the check chain bracket, and is farther from the mission case than the pin support position of the check chain bracket. Since the fulcrum of the lower link is disposed in the lower link, it is possible to easily remove the lower link from the pin by removing the retaining means near the tip of the pin.

Since the hydraulic valve of the working machine lifting device is arranged on one surface of the valve case and the piping path between the hydraulic valves is provided on the other surface of the valve case as described in claim 5, the machining is performed. It is easy and the processing man-hour can be reduced. In addition, the flexibility of piping is high and it is advantageous in design,
Since it is not necessary to make the inside of the hydraulic valve case thick, it is possible to reduce the weight.

[Brief description of drawings]

FIG. 1 is a left side view of a tractor.

FIG. 2 is a left side view showing the first embodiment of the working machine lifting device according to the present invention.

FIG. 3 is a rear view showing the first embodiment of the working machine lifting device of the present invention.

FIG. 4 is a plan view showing a first embodiment of the work implement lifting device of the present invention.

FIG. 5 is a perspective view of a check chain bracket.

FIG. 6 is a left side view showing a second embodiment of the working machine lifting device of the present invention.

FIG. 7 is a partial left side sectional view of a hydraulic valve case according to an embodiment of the present invention.

FIG. 8 is a plan view of a hydraulic valve case that is an embodiment of the present invention.

FIG. 9 is a plan view of a conventional hydraulic valve case.

FIG. 10 is a plan view showing a piping path of a flow control swing valve.

FIG. 11 is a rear partial cross-sectional view showing a piping path of a flow control swing valve.

[Explanation of symbols]

1 Working machine lifting device 2L / 2R Exterior type cylinder 2a cylinder case 2b Case side pivot 2c cylinder rod 2d Rod side pivot part 3 hydraulic valve case 4 rear mission case 7 pin fixing bracket 8 pin 11 check chain bracket 13 Lower Link 19 Flocon swing valve 20 hydraulic lift valve 35/36 piping

Claims (5)

[Claims] 1. In a tractor in which an exterior cylinder is arranged laterally of a mission case and which is provided with a work implement lifting device that operates by the exterior cylinder, a support point of the exterior cylinder and a fulcrum of a lower link connecting the work implement. A work implement lifting device for a tractor, wherein and are arranged on the same axis. 2. The work implement lifting device for a tractor according to claim 1, wherein a support point of the exterior cylinder and a fulcrum of the lower link are rotatably supported by the same pin. 3. The work implement lifting device for a tractor according to claim 2, wherein the pin is supported by a mission case and a lower link check chain bracket. 4. A support point of the exterior cylinder is arranged at a position closer to the mission case than a pin support position of the check chain bracket, and a lower link fulcrum is located at a position farther from the mission case than the pin support position of the check chain bracket. The working machine lifting device for a tractor according to claim 3, wherein: 5. A hydraulic valve of the working machine lifting device is arranged on one surface of a valve case, and a piping path between the hydraulic valves is provided on the other surface of the valve case. A work implement lifting device for a tractor according to claim 4.