JPH09263149A - Travelling device for service vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply extend and contract the length of a front axle by hydraulic pressure and allow the posture of a machine body to draw to the horizontal for a stable operation when a service car having the relatively high center of gravity for front wheel drive and steering goes in and out of a path through a field to a paddy field for example, and the longitudinal posture of the machine body is inclined remarkably forward or backward during unloading a carrier or the like in travelling on the paddy. SOLUTION: A front axle case is divided into aupper front axle case 12 and lower front axle case 13 to be supported pivotably, expansionally and contractibly. A hydraulic expansion device disposed approximately parallel to the axes of both front axle cases is provided on both sides of the front axle case. A hydraulic circuit disposed already for lifting a service machine is used so that the front axle expansion-contraction and the service machine lift can be changed by a change-over device simultaneously and the length of the front axle case can be extended and contracted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention A working device for a working vehicle, in which a working machine is mounted on a rear side of a machine body so as to be able to move up and down, and front wheels are driven by power transmitted through a transmission case and the front wheels are steered. Regarding

[0002]

2. Description of the Related Art Traveling devices for driving front wheels and for fixing front axle lengths of working vehicles for steering the front wheels are already known. In addition, even a traveling device in which the length of the front axle can be expanded and contracted is already known in which a hydraulic circuit of an artificial or hydraulic expansion / contraction device is added to another system.

[0003]

SUMMARY OF THE INVENTION Therefore, the present invention uses a hydraulic circuit which is already provided for raising and lowering the working machine, and makes it possible to switch between the expansion and contraction of the front axle and the lifting and lowering of the working machine by a switching device. Aim to easily extend and contract the length of the front axle.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a working machine (3) is mounted on the rear of the machine body so as to be able to move up and down by a hydraulic device (2), and a transmission case (1
In the working vehicle (1) in which the front wheels 4 can be steered freely by the power transmitted via the front wheel transmission case (1).
1) Upper front axle case (12) fixed to the left and right sides, and the upper front axle case (12)
A lower front axle case (13) integral with the pitman arm (16) which is pivotally and slidably fitted to the pit and is steered via a tie rod (17), and an upper portion of the upper front axle case (12). And an upper arm (15) rotatably fixed to the upper front axle case (12) and a side surface of the upper front axle case (12) and the lower front axle case (13), substantially parallel to the axes of both front axle cases. The hydraulic expansion / contraction device (20) and an elastic member (2) that exerts a biasing force against the hydraulic pressure of the hydraulic expansion / contraction device (20).
2), the upper arm (15) and the pitman arm (16) are connected to the hydraulic expansion and contraction device (20) via the elastic member 22, and the upper front axle case 12 is connected to the upper front axle case 12. The lower front axle case (13) is made expandable and contractible, and the hydraulic circuit of the hydraulic expansion / contraction device (20) is provided in the hydraulic circuit for lifting the working machine,
The switching device (32) makes it possible to switch between expansion and contraction of the front axle and lifting and lowering of the working machine, thereby solving the above-mentioned problems.

(Operation) A working machine (3) is mounted on the rear side of the machine body so that it can be moved up and down by a hydraulic system (2), and a transmission case (11) is installed.
When the work vehicle (1) that drives the front wheels (4) by the power transmitted through the steering wheel and steers the front wheels (4) enters and leaves a field with a step from a farm road, or travels in a wetland, When loading or unloading on a carrier, the aircraft's front-rear posture is significantly tilted forward,
Alternatively, when the vehicle tilts backward, the machine body is stopped from moving, the working machine lifting lever (33) is operated while operating the switching device (32), and the front axle length is increased by using the working machine lifting hydraulic circuit. By expanding and contracting the height and making the front and rear posture of the aircraft close to horizontal, stable running is ensured and safety is ensured.

The reference numerals in the parentheses are for the purpose of contrasting with the drawings, but do not limit the structure of the present invention.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The agricultural vehicle 1 is shown in FIGS. 1 (a) and 1 (b).
As shown in FIG. 3, a working machine 3 is mounted on the rear side of the machine body via a hydraulic lifting device 2, and the front wheels 4 and the rear wheels 5 are driven to travel in an uncultivated field to perform agricultural work.

The above-mentioned agricultural work is often carried out in naps, and the ground height is set as high as possible so that the lower part of the machine body does not contact the crop and damage the crop. It is composed high.

The farm field is located at a low position from the farm road, and when entering or exiting a farm field with a step, the agricultural vehicle 1 remarkably leans forward or backward, which causes unstable work in the front-rear direction.

Also, when loading and unloading on a truck or the like, similarly, a significantly leaning forward or backward leaning posture occurs, and the work becomes unstable in the longitudinal direction.

The front wheels 4 of the agricultural vehicle 1 are, as shown in FIG. 2, an upper front axle case 12 fixed to the left and right sides of a front wheel transmission case 11 arranged in the lower center of the machine body,
It is supported by a lower front axle case 13 which is fitted to the upper front axle case 12 so as to be rotatable and slidable, and is driven by a transmission member incorporated in the front wheel transmission case 11, the upper front axle case 12 and the lower front axle case 13. Has been done.

An arm holder 14 is provided above the upper front axle case 12 also as a lid, and an upper arm 15 is loosely fixed to the outer diameter of the arm holder 14.

A pitman arm 16 is provided laterally integrally with the lower front axle case 13, and the tip of the pitman arm 16 is provided on the other side of the pitman arm 1.
A tie rod 17 interlocks with the tip of 6a.

On the side surfaces of the upper front axle case 12 and the lower front axle case 13, the hydraulic cylinder 20, the hydraulic piston 21, and the hydraulic pressure of the hydraulic cylinder 20 are placed substantially parallel to the axes of the front axle cases 12 and 13. A spring 22 that exerts a biasing force is provided.

The hydraulic piston 21 is rotatably supported upward in the base hole 16a of the pitman arm 16, and the hydraulic cylinder 20 and the spring 22 are downward rotatably supported in the tip hole 15a of the upper arm 15. I support you.

The hydraulic piston 21 is inserted into the hydraulic cylinder 20, hydraulic oil is made to flow into the cylinder head 20a, the length of the front axle is extended against the biasing force of the spring 22, and The hydraulic oil is caused to flow out and restored to its original length by the biasing force of the spring 22.

Cylinder head 2 of the hydraulic cylinder 20
The hydraulic oil for inflowing and outflowing to the work machine 0a is diverted as it is by the switching lever 34 provided in the middle of the hydraulic circuit for lifting the working machine.

Explaining the hydraulic circuit of the present invention, as shown in FIG. 3, the transmission 2 of the agricultural vehicle 1 is shown.
Two hydraulic pumps 26 and 27 are driven by 5, one hydraulic pump 26 sends oil to a hydraulic circuit 28 for raising and lowering the working machine, and the other hydraulic pump 27 sends oil to a hydraulic circuit 29 for operating the power steering. are doing.

The hydraulic circuit 28 includes a control valve 3 with five positions.
0, and a switching valve 32 for switching between the hydraulic cylinder 20 and the lift cylinder 31 for elevating and lowering the working machine in a further circuit.
Is interposed.

Of the five positions of the control valve 30, the three positions on the left in FIG. 3 are for the lift cylinder 31, and the two positions on the right are hydraulic cylinders for extending and contracting the length of the left and right front axle cases of the present invention. The operation lever 33 is operated so as to be used for 20.

The left position of the switching valve 32 is used for the lift cylinder 31, and the right position thereof is used for the hydraulic cylinder 20 for extending and contracting the length of the front axle case.
Operate with 4.

By expanding and contracting the hydraulic cylinder 20, the relative positions of the upper front axle case 12 and the lower front axle case 13 are changed to expand and contract the length of the front axle case. The upper end portion 35a is composed of a slidable spline shaft, transmits power, and is capable of coping with expansion and contraction of the length of the external front axle case.

Further, since the pitman arm 16 is formed integrally with the lower front axle case 13 and the tie rod 17 can be arranged at an appropriate height,
Tie rod 17 connecting left and right pitman arms 16
Has a simpler structure and less damage to crops during napping operations.

Further, as shown in FIG. 1 (a), an elastic sheet 36, which is flexible enough to be hung by its own weight when traveling is stopped, is provided on the entire front surface of the tie rod 17 from the lower part of the machine body so that It protects the structure that is protruding from the obstacles in the lower part of the fuselage.

Next, the operation of the embodiment of the present invention will be described.

On the basis of the above structure, the agricultural vehicle 1 is significantly inclined forward or backward when entering or exiting a farm field, loading or unloading on a truck, etc. When the vehicle 1 is stopped running and the operating lever 33 is operated in the upward direction while pushing the switching lever 34 toward the hydraulic cylinder 20 side with one hand, the hydraulic cylinder 2
0, hydraulic oil flows in, the length of the hydraulic cylinder 20 extends against the urging force of the spring 22, and the upper front axle case 12 and the lower front axle case 13
The relative length of the aircraft becomes longer, and the body posture is tilted forward.

Similarly, when the body posture is tilted backward, similarly, the traveling of the commercial vehicle 1 is stopped in advance, and contrary to the above, while pushing the switching lever 34 to the lift cylinder 31 side with one hand, the operation lever 33 is operated. When operated in the lowering direction, the hydraulic oil in the hydraulic cylinder 20 flows out and returns to the tank due to the urging force of the spring 22, and the length of the hydraulic cylinder 20 is shortened, and the upper front axle case 12 and the lower front axle case 13 are reduced. The relative length of is shortened, and the body posture can be tilted backward.

[0029]

According to the present invention, in a working vehicle in which a working machine is mounted on the rear side of a machine body so as to be able to move up and down by a hydraulic device, and front wheels can be steered by power transmitted through the transmission case, An upper front axle case fixed to the left and right side, a lower front axle case which is fitted to the upper front axle case in a rotatable and slidable manner and is integrated with a pitman arm which is steered via a tie rod, and the upper section. An upper arm rotatably fixed to the upper part of the front axle case, and a hydraulic expansion / contraction device disposed on the side surfaces of the upper front axle case and the lower front axle case substantially parallel to the axis of both front axle cases. An elastic member that exerts an urging force against the hydraulic pressure of the hydraulic expansion / contraction device, and includes the upper arm and the pitman arm. The hydraulic telescopic device and through the resilient member coupled to the telescopic said lower front axle case to the upper front axle case,
Moreover, the hydraulic circuit of the hydraulic expansion / contraction device is provided in the hydraulic circuit for lifting / lowering the working machine, and the switching device can switch between the expansion / contraction of the front axle and the lifting / lowering of the working machine. Unstable posture due to tilting or backward tilting has been corrected, and safe work can now be performed.

[Brief description of drawings]

1A is a plan view of an agricultural vehicle, and FIG. 1B is a side view of the agricultural vehicle.

FIG. 2 is a vertical sectional view of a front axle.

FIG. 3 is a hydraulic circuit diagram according to the embodiment of the present invention.

[Explanation of symbols]

 1 Agricultural Vehicle 4 Front Wheel 12 Upper Front Axle 13 Lower Front Axle 14 Pitman Arm 20 Hydraulic Cylinder 30 Control Valve 32 Switching Valve 33 Switching Lever

Claims (2)

[Claims] 1. A working vehicle in which a working machine is mounted on a rear side of a machine body so as to be capable of moving up and down by a hydraulic device, and front wheels can be steered by power transmitted through a transmission case. The working vehicle is fixed to the left and right sides of the front case. Of the upper front axle case, a lower front axle case integrated with the pitman arm that is pivotally and slidably fitted to the upper front axle case and is steered through a tie rod, and the upper front axle case An upper arm rotatably fixed to the upper part; a hydraulic expansion / contraction device disposed on the side surfaces of the upper front axle case and the lower front axle case substantially parallel to the axes of both front axle cases; An elastic member that exerts a biasing force against the hydraulic pressure of the device, the upper arm and the pitman arm being A traveling device for a working vehicle characterized in that the lower front axle case can be freely expanded and contracted with respect to the upper front axle case by connecting to a pressure expansion / contraction device via the elastic member. 2. The working circuit according to claim 1, wherein a hydraulic circuit of the hydraulic expansion / contraction device is provided in a hydraulic circuit for lifting / lowering a working machine, and a switching device can switch between expansion / contraction of the front axle and lifting / lowering of the working machine. Vehicle running device.