JPH0481374A - Tractor - Google Patents

Abstract

PURPOSE:To improve reliability by installing an operating valve for a hydraulic steering circuit, between the left and right transmission shaft housings and a power shaft set between the transmission shaft housings, preventing the interlocking mechanism part of a steering device from being obstructed, and permitting the direct manual operation for an operating valve in case of the generation of troubles. CONSTITUTION:As for an agricultural tractor, a rear axle is axially installed at the rear edge part of a transmission shaft housing 8 ranging from the left and right side parts of a transmission case 7 to the rear part, and a power taking-out shaft 2 for transmitting a working device is installed between the left and right transmission shaft housing 8, and an operating valve 11 for the hydraulic steering circuits 10 for the front and rear wheels 13 and 9 is installed between the transmission shaft housing 8 and the power taking-out shaft 2. The operating valve 11 is constituted of a front wheel control valve 42 for controlling a front wheel steering cylinder 36, and a rear wheel control valve 43 which is installed in free selection by a solenoid C and controls a rear wheel steering cylinder 38. A floor 12 at the center part between the transmission housing 8 is installed in demountable manner so as to cover the part between the left and right floors 51, and the manual operation parts 44-46 of the control valves 42 and 43 can be operated when the floor 12 is demounted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a tractor, and can be used as an agricultural management work machine.

(Prior Art and Problems to be Solved by the Invention) In a small tractor used for administrative work, a power take-off shaft is connected from a transmission case at the front of the vehicle body to a work bag W4 mounted at the rear. , there is a type in which the working device 4 is linked, but since this power take-off shaft is located across the lower part of the vehicle body in the longitudinal direction, it gets in the way of the steering device for the front wheels and rear wheels. easy.

(Means for Solving the Problems) In the present invention, a rear wheel 9 is mounted on the rear end of a transmission shaft housing 8 extending rearward from both left and right sides of a transmission case 7, and a rear wheel 9 is mounted on the rear end of a transmission shaft housing 8 extending rearward from both left and right sides of a transmission case 7. A power take-off shaft 2 for transmitting power to a working device 4 connected to the rear of the vehicle body 1 is provided, and between the transmission shaft housing 8 and the power take-off shaft 2, the hydraulic steering circuit 10 for the front and rear wheels 13, 9 is operated. The tractor is provided with a valve 11 and a floor 12 that can be opened and closed on the upper side.

(Operation and Effects of the Invention) Power is transmitted from the transmission case 7 at the front of the vehicle body 1 to the rear wheels 9 via the transmission shafts in the transmission shaft housings 8 on both left and right sides, and the power take-off shaft between these transmission shaft housings 8. 2, a working device 4 attached to the rear of the vehicle body is transmitted.

Steering during running is performed by steering operation, and the front wheels 13 and rear wheels 9 are steered under the control of the hydraulic steering circuit 1o. At this time, if the controlled steering of the hydraulic steering circuit 10 does not work for some reason, the front wheels 13 and the rear wheels 9 can be temporarily operated by opening the floor 12 and manually operating the lower operation valve 11. The helm can be operated.

As described above, since the operation valve 11 of the hydraulic steering circuit 10 is provided between the left and right transmission shaft housings 8 and the power shaft 2 between the transmission shaft housings 8, the interlocking mechanism of the steering device is To prevent it from getting in the way, if the steering control is malfunctioning for some reason and the steering cannot be operated, remove the floor 12 above the operation valve 11.
By directly manually operating the operation valve 11, the front wheels 13 or the rear wheels 9 can be temporarily steered, making it easy to take measures after a failure occurs.

(Embodiment) Referring to FIGS. 19 and 20, the tractor body 1 includes a front wheel bracket 14 at the front, a transmission case 7, a transmission shaft housing 8 at the rear, and the like.
The front wheel housing 15 is supported by a center pivot so as to be able to roll freely, and the front wheels 13 are mounted on both left and right ends of the front wheel housing 15 so as to be freely steerable by a front shaft steering mechanism 16. , an engine 17 is mounted on the upper side.

The transmission case 7 integrated on the rear side of the front wheel bracket 14 receives power from the engine 17 via a belt 18 and the like, and connects the transmission device in the front wheel housing 15, the power take-off shaft 2, and the rear wheel 9. It has a structure in which variable speed is transmitted to the transmission shaft etc. in the transmission shaft housing 8. The transmission shaft housing 8 projects rearward from both left and right sides of the transmission case 7, and has a rear wheel 9 mounted thereon at its rear end so that it can be freely steered by a rear wheel steering mechanism 19.

The power take-off shaft 2 protrudes rearward from between the left and right transmission shaft housings 8 on the rear side of the transmission case 7, is rotatably supported by a bearing member 20 that is integral with the vehicle body 1, and is further supported by a universal joint 3 or a spline. It can be connected to the input shaft 5 of the rear working device 4 via an expansion joint or the like. A connecting member 21 is provided between the left and right transmission shaft housings 8, and a pilot seat 2 is provided on the upper side.
2 is installed. Further, a lift shaft 23 is provided at the lower part between the transmission shaft housings 8, and supports a lift link 24 so as to be movable up and down.At the rear end of the lift link 24, a tilling shaft 26 having a tilling claw 25 and a tilling shaft 26 are provided at the rear end of the lift link 24. , a working device 4 having a soil cultivator 27 etc. can be attached and detached with a hitch 28, and the input shaft 5 at the top of the working device 4 is made to protrude forward, and the power output shaft 2
The rear end portions can be transmission connected by spline fitting or the like.

A lift arm 29 is connected to the lift link 24 and is raised and lowered by a hydraulic cylinder 33.

30 is a front wheel axle, 31 is a rear wheel axle, and 32 is a steering handle.

1, 14, and 20, the pitman arm 34 of the steering mechanism 16 of the front wheel 13 is rotatably provided in the front wheel housing 15, and is operated by hydraulic pressure via a link mechanism 35. It is interlocked with the front steering cylinder 36, and the steering is controlled by the expansion and contraction of the front steering cylinder 36.

Further, the pitman arm 37 of the steering mechanism 19 of the rear wheel 9 is located below the connecting member 21 that connects the transmission shaft housing 8 and is rotatably provided, and is rotatable in the left-right direction with respect to the structural members of the vehicle body 1. The rotation is controlled by a rear shaft steering cylinder 38 using hydraulic pressure that extends and contracts.

The steering operations for these front wheels 13 and rear wheels 9 are as follows.

It is located under the transmission shaft housing 8, the power take-off shaft 2, etc., and is operated by the steering handle 32, but via the orbit roll 39 of the hydraulic steering circuit 1o,
This is done via the operating valve 11. This hydraulic steering circuit 10
A hydraulic pump 4o driven by the engine 17 operates a flow dividing valve 41, an orbit roll 39 switched by turning the steering handle 32, an operation valve 11, a front steering cylinder 36, and a rear steering cylinder 38. The front steering cylinder 36 and the rear steering cylinder 38 are controlled at a predetermined angle and direction according to the control mode of the electronic controller that controls the operation of the operating valve 11.

The operation valve 11 is attached to a bracket 41 that connects the left and right transmission housings 8 between the transmission shaft housing 8 and the power extraction shaft 2 .

A front wheel control valve 42 is provided on the front wheel steering cylinder 36 side so that it can be switched freely by a solenoid C, and a rear wheel control valve 43 is provided on the rear shaft steering cylinder 38 side so that it can be switched freely between solenoids A and B. . Also, these solenoids A and B
, C has a configuration that can be switched even if it is directly pressed manually,
This manual operation part 44.45.46 is connected to each valve 42.4.
3 itself, and is located below the floor 12.

The steering modes include a front wheel steering mode in which only the front wheels 13 are steered, a rear wheel steering mode in which only the rear wheels 9 are steered, and a four-wheel mode in which the front wheels 13 and rear wheels 9 are steered in the same direction. steering mode,
and a reverse steering mode in which the front wheels 13 and rear wheels 9 are steered in opposite directions.In the front axle steering mode (Fig. 15), solenoids A, B, and C are all turned OFF and the 14th
As shown in the figure. At this time, the neutral position of the pitman arm 37 of the rear wheel 9 is detected by the limit switch 47. In rear wheel steering mode (Fig. 16).

When the solenoids A and C are turned on, the neutral position of the pitman arm 34 of the front wheel 13 is detected by the limit switch 48. In the four-wheel steering mode (FIG. 17), only solenoid B is turned on to interlock the steering of the front wheels 13 and rear wheels 9 in the same direction.

In reverse steering mode (Fig. 18), only solenoid A is turned OFF.
N, the front wheels 13 and rear wheels 9 are steered in opposite directions.

Note that the lift control valve 4 is connected to the diverter valve 41.
9 allows the hydraulic cylinder 33 of the working device 4 to expand and contract.

Floors 51 on both left and right sides are mounted and supported on the transmission shaft housing 8 by floor support frames 50 that protrude outward. It is detachably provided so as to cover the whole area. By removing the floor 12, the manual operation section 46 of each front wheel control valve 42 and the rear wheel control valve 43 can be removed.
It is possible to operate the manual operation parts 44, 45 and the like. 5
An angle sensor 2.53 detects the steering angles of the front wheels 13, rear wheels 9, etc.

In FIGS. 1 to 5, a shaft holding member 6 connecting the left and right sides is provided at the rear of the lift link 24 that moves up and down with respect to the transmission shaft housing 8, and the power take-off shaft 2 is rotated at the center of the left and right parts. A recess 54 is formed to freely fit and support. The lowest position of the shaft holding member 6 is appropriately lower than the interlocking position of the working device 4 with respect to the input shaft 5, and is set at a height that does not interfere with the interlocking operation.

Note that the shaft holding member 6 may be supported by a member provided integrally with the transmission shaft housing 8.

In FIGS. 6 to 13, the front wheel housing 15 is
By interposing the spacer housing 56, the left and right treads can be adjusted, and the steering angle by the steering mechanism 16 changes as the tread is adjusted.
The steering stopper 55 for locking the steering limit position of the front wheels 13 can be adjusted.

The front wheel housing 15 has steering cases 62 on both left and right sides.
An end case 57 that supports a rotatably steerable end case 57 is provided so that it can be joined and separated, and spacer housings 56 of different lengths can be exchangeably connected between the joined parts. At the same time, the length of the tie rod of the front wheel steering mechanism 16 is also adjusted. The front wheel 58, which transmits power to the front wheel shaft 30 through the differential device 57 in the center of the front wheel housing 15, may be configured to be interlocked by expansion and contraction using a spline shaft, or may be interlocked by a connecting shaft with a length depending on the tread. good.

Regarding the steering stopper 55 for the end case 57 of the steering case 62, in FIGS. 7 to 10, the end case 5
A washer 59 having a thickness suitable for changing the tread is fitted on the 7 side to adjust the protrusion height. , the rotation is stopped at the steering limit position.

In addition, in FIGS. 11 to 13, the steering stopper 55 that the stopper 61 abuts is in the form of an arm that is rotatable around the ratio axis 63, and one end of this arm is connected to the joint rib of the spacer housing 56 at a predetermined depth. The depth of this recess 64 is set according to the length of the spacer housing, and the steering stopper 55
When the arm is pushed by the stopper 61, it comes into contact with the recess 64 to prevent the steering case 62 from rotating.

According to this, the position of the steering stopper 55 is automatically determined by replacing the spacer housing 56.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an enlarged plan view of a part, Fig. 2 is a front sectional view of a part, Fig. 3, and Fig. 4.
FIG. 5 is an enlarged side view of a portion of the housing, and FIG. 6 is an enlarged front sectional view of the front wheel housing.
Figure 7 is a front view of a part of it, Figure 8 is a side view of it, and Figure 9 is a front view of a part of it.
The figure is a partially exploded plan view, Figure 10 is an enlarged slope view of a part, Figure 11 is a front view showing another embodiment of the part, Figure 12 is a side view thereof, and Figure 13 is a part of it. Fig. 14 is a hydraulic circuit diagram, Figs. 15 to 18 are plan operation diagrams showing steering modes, Fig. 19 is a side view of the tractor, and Fig. 20 is a partial plan view. It is. (Explanation of symbols) 1 Vehicle body 2 Power take-off shaft 4 Working device
7 Transmission case 8 Transmission shaft housing 9 Rear wheel 10 Hydraulic steering circuit 11 Operation valve 12 Floor 13 Front wheel

Claims (1)

[Claims] A rear wheel 9 is mounted on the rear end of a transmission shaft housing 8 extending from both left and right sides of the transmission case 7 to the rear, and a working device 4 connected to the rear of the vehicle body 1 is mounted between these left and right transmission shaft housings 8. A power take-off shaft 2 for transmitting power is provided, and an operating valve 11 for a hydraulic steering circuit 10 for the front and rear wheels 13 and 9 is provided between the transmission shaft housing 8 and the power take-off shaft 2, and a floor 12 that can be opened and closed is provided on the upper side. A tractor equipped with