JP2002249064A - Steering device for tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength and the efficiency in a steering link structure of a tractor. SOLUTION: In this tractor capable of being changed between a low floor specification and a standard specification, and having a constitution that front wheels are steered by connecting the front wheels to steering knuckle arms 35 connected to tips of cylinder rods 32a of hydraulic cylinders 32 for power steering through tie rods 33, a distance C between an intersection point of an axis O1 of the tie rod and an axis O2 of a fulcrum shaft 36 for pivoting the tie rod and the steering knuckle arm, and an intersection point of the axis O2 of the fulcrum shaft 36 and a axis O3 in the width direction of the knuckle arm is a length determined to be approximately half of a height A changed between the low floor specification and the standard specification, and the tie rod is connected to a lower part of the knuckle arm in the low floor specification, and connected to an upper part of the knuckle arm in the standard specification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement of a steering drive unit for power steering using a double rod type steering cylinder.

[0002]

2. Description of the Related Art Conventionally, in order to reduce the height of a tractor, an offset gear case is interposed between an axle case of a front axle and a fixed case on a front wheel side, and a knuckle arm provided on a rotating case. A technique for connecting a tie rod to the steering for steering is known. For example, there is a technique disclosed in Japanese Utility Model Laid-Open Publication No. 61-169626. Further, a technique in which a hydraulic cylinder for power steering and a tie rod arranged in a front axle case of a tractor are substantially parallel to each other is known. For example, JP-A-7-257
412 publication.

[0003]

However, when a hydraulic cylinder for power steering is mounted on an axle case as a low-floor type in which an offset gear case is interposed between an axle case and a fixed case, the tie rod becomes short. The mounting angle becomes large, and a large bending occurs in the cylinder rod and the like, and a strong structure is required. In addition, because bending force occurs,
Since the link efficiency is reduced, a large cylinder is required, and there is a problem that it must be further strengthened.

[0004]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

More specifically, in the tractor according to the present invention, the front wheel is connected to a knuckle arm via a tie rod at the tip of a cylinder rod of a hydraulic cylinder for power steering, and the front wheel is operated. In the configuration in which the tie rod can be oriented, the intersection between the axis of the tie rod, the axis of the fulcrum shaft that pivotally connects the tie rod and the knuckle arm, and the intersection of the axis of the fulcrum shaft and the center line in the width direction of the knuckle arm. The distance between them is about half of the height that is changed between the low floor specification and the standard specification.

According to a second aspect, the tie rod is
It is connected to the lower part of the knuckle arm for the low floor specification, and connected to the upper part of the knuckle arm for the standard specification.

[0007]

Next, embodiments of the present invention will be described. 1 is a side view of a tractor, FIG. 2 is a front sectional view of a front axle of a low floor tractor, FIG. 3 is a front view of a front axle of a low floor tractor, and FIG. 4 is a front view of a front axle of a standard tractor. 5 is an enlarged front view of the front axle of the low floor tractor, and FIG. 6 is a front view of the low floor tractor without the power steering device.

1, the engine 2 is mounted in a bonnet 1 at the front, a steering handle 3 is disposed behind the bonnet 1, and a driver's seat 4 on which an operator sits is provided. I have. A transmission case is connected to the rear of the engine 2, and rear wheels 5 are supported on both sides of the rear of the transmission case via rear axle cases.

A front wheel power take-out case 6 is provided at the lower part of the transmission case. A front wheel drive output shaft projects forward from the front wheel power take-out case 6, and a differential in a front axle case 31 is provided via a transmission shaft 7. Power is transmitted to the front axle case 31. Rotating portions of the front wheel drive device of the present invention are disposed on both sides of the front axle case 31, and front wheels 8 are mounted on both outer ends of the rotating portion. 8 is configured to be drivable.

In FIG. 2, the power from the differential device is transmitted to a front differential shaft 10 mounted on a front axle case 31. At both ends of the front axle case 31, fixed cases 12 Is fixed,
In the case of a low floor type, a fixed case 12 is fixed via an offset gear case 11, and a lower portion of the fixed case 12 forms a cylindrical king pin 13 and extends downward. 2 and 3 show the low floor specification, and FIG. 4 shows the standard specification.

One end of a front differential shaft 10 is inserted into a lower portion of the offset gear case 11 and is rotatably supported via a bearing. A transmission gear is fixedly mounted on the front differential shaft 10 in the offset gear case 11. A shaft 25 is rotatably supported on the upper portion of the offset gear case 11 and one end of the fixed case 12 via a bearing. A transmission gear is fixedly mounted on one end of the shaft 25 and meshes with the transmission gear. The bevel gear 13a is spline-fitted and fixed, and the bevel gear 13a meshes with the bevel gear 13b spline-fitted and fixed at the upper end of the longitudinal axis 14.

The longitudinal axis 14 passes through the inside of the king pin 13 from the fixed case 12, the upper end is rotatably supported by the fixed case 16 via a bearing externally fitted to the bevel gear 13b, and the lower end protrudes from the king pin 13. Then, it is configured to be inserted into a shaft portion of a bevel gear 17a rotatably supported via a bearing 16 at a lower portion of a rotating case 15 and spline-fitted to transmit power. The large-diameter bevel gear 17b meshes with the large-diameter bevel gear 17b.
7b is fixedly mounted on an axle 21 rotatably supported by bearings 19 and 20 serving as axle support bearings on a rotating case 15 and a supporting case 18 fixedly provided on the side of the rotating case 15. The front wheel 8 is fixed to the flange portion 21a provided at the outer end by a bolt, and the reduction bevel gear mechanism 17
The power is transmitted to the axle 21 via the drive shaft and the front wheels 8 are driven.

The rotating case 15 is provided with the king pin 13.
Are rotatably supported via an upper bearing 22 and a lower bearing 23 serving as king pin support bearings. The upper bearing 22 is fitted on the lower part of the lower bearing so that dust and the like do not enter through a gap between the upper bearing 22 and the outer bearing. A knuckle arm 35 projects from the rotating case 15 and is connected to the power steering hydraulic cylinder 32 (hereinafter referred to as a power steering cylinder) via a tie rod 33 to be described later. The structure is such that the front wheel 8 can be rotated via the knuckle arm 35 and the like by expanding and contracting the cylinder 32.

As shown in FIG. 3, the front axle case 31 is composed of left and right cases 31R and 31L and a center case 31M disposed between the left and right cases 31R and 31L.
11 and the rotating cases 15 are fixedly provided. The input shaft protrudes rearward from the rear surface of the center case 31M and is connected to the transmission shaft 7 via a universal joint or the like (not shown) so that the power transmitted to the input shaft is transmitted to a differential device or the like in the front axle case 31. The drive is transmitted to the front wheels 9 via the motor. A center pin protrudes forward from the left and right center of the front axle case 31 and is supported by the front frame so as to be swingable left and right.

A power steering cylinder 32 is provided horizontally on the front surface of the center case 31M in the left-right horizontal direction. The power steering cylinder 32 is a double rod type in which cylinder rods 32a project from both sides. Hereinafter, one side is described because it is configured symmetrically. The tip of the cylinder rod 32a is connected to a tie rod 33 via a spherical joint 34, and the other end of the tie rod 33 is connected to a lower portion of a knuckle arm 35. The tie rod 33 is configured so as to be positioned substantially in line with the power steering cylinder 32 when viewed straight ahead when traveling straight. Therefore, the bending force generated in the vertical direction is reduced. The knuckle arm 35 is fixed to a side of the rotating case 15 that supports the front wheel 8, and the front wheel 8 can be rotated about the king pin 13 by rotating the knuckle arm 35.

The intersection of the axis O1 of the tie rod 33, the axis O2 of a fulcrum shaft 36 for pivotally connecting the tie rod 33 and the knuckle arm 35, and the vertical width of the axis O2 of the fulcrum shaft 36 and the knuckle arm 35 The distance C between the intersection with the center line O3 of the direction is set to about half the length A of the height A that is changed between the low floor specification and the standard specification. That is, the height A to be changed between the low floor specification and the standard specification is the distance A between the axis of the front differential shaft 10 and the axis of the shaft 25 shown in FIG. At the time of low floor specification shown in 5,
When the tie rod 33 is attached to the lower side of the knuckle arm 35 and when it is attached to the upper side (33 '), the axis O1 and O1' of the tie rod 33 and the fulcrum shaft 36 for pivotally connecting the tie rod 33 and the knuckle arm 35 are formed. Rotation axis O
The distance is approximately equal to the distance B between the intersections of the two (A ≒
B). The center line O3 in the vertical width direction of the knuckle arm 35 becomes the symmetric center line O3 when the tie rod 33 is mounted below the knuckle arm 35 and when it is mounted above the knuckle arm 35 in the low floor specification. Intersection,
The distance C between the intersections of O2 and O3 is about half the distance A between the axes. (A ≒ B ≒ 2C)

In such a configuration, when the offset gear case 11 is not provided between the front axle case 31 and the fixed case 12, the other end of the tie rod 33 is placed above the knuckle arm 35 as shown in FIG. By being connected, the tie rod 33 is positioned substantially in line with the power steering cylinder 32 when viewed straight when the vehicle is traveling straight. When the offset gear case 11 is provided between the front axle case 31 and the fixed case 12, the other end of the tie rod 33 is connected to the lower part of the knuckle arm 35 as shown in FIG. 33 is positioned substantially in line with the power steering cylinder 32 in a front view. In such a connected state, even if the power steering cylinder 32 is operated at the time of turning, the force is transmitted in the straight traveling direction without bending, so that a large bending does not occur in the cylinder rod or the like. In the low-floor specification and the standard specification, the same fixed case 12, rotating case 15, power steering device, and the like can be specified, and only the offset gear case 11 needs to be replaced, and the specification can be easily changed. is there.

In the case where the front axle case 31 is not equipped with the power steering cylinder 32, FIG.
As shown in the figure, even if the offset gear case 11 is provided between the front axle case 31 and the fixed case 12,
Since a long tie rod is used, the mounting angle of the tie rod tie rod 33 does not change significantly.

[0019]

The present invention is configured as described above.
The following effects are obtained. That is, as described in claim 1, a tractor that can be changed to a low floor specification and a standard specification, in which a front wheel can be steered by being connected to a knuckle arm via a tie rod at the end of a cylinder rod of a hydraulic cylinder for power steering. Between the intersection of the axis of the tie rod, the axis of the fulcrum shaft that pivotally connects the tie rod and the knuckle arm, and the intersection of the axis of the fulcrum shaft and the center line in the width direction of the knuckle arm. Since the distance was about half the height of the height changing between the low floor specification and the standard specification,
In both low-floor and standard specifications, the tie rods and cylinder rods can be arranged substantially in a straight line when viewed straight ahead, and the link power transmission efficiency of the steering link mechanism can be improved. The output of the steering cylinder can be reduced, an excessive bending force can be prevented from being applied to the steering link mechanism, and the weight of the link mechanism can be reduced. Also,
The same power steering device, knuckle arm and tie rod can be used even if the specifications are changed.

As described in claim 2, the tie rod is
It is connected to the lower part of the knuckle arm at the time of low floor specification, and it is connected to the upper part of the knuckle arm at the time of standard specification, so that it is easy to assemble even if the specification is changed, and the knuckle arm has a vertically symmetrical configuration. And the configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a front sectional view of a front axle of a low-floor tractor.

FIG. 3 is a front view of a front axle of the low-floor tractor.

FIG. 4 is a front view of a front axle of a standard tractor.

FIG. 5 is an enlarged front view of a front axle of the low-floor tractor.

FIG. 6 is a front view of the low-floor tractor.

[Explanation of symbols]

 11 Offset gear case 12 Fixed case 31 Front axle case 32 Power steering cylinder 32a Cylinder rod 33 Tie rod 35 Knuckle arm

Claims (2)

[Claims] 1. A tractor which can be changed to a low floor specification and a standard specification, wherein a front wheel can be steered by connecting a front end of a cylinder rod of a power steering hydraulic cylinder to a knuckle arm via a tie rod. The distance between the intersection of the axis of the tie rod, the axis of the fulcrum shaft that pivotally connects the tie rod and the knuckle arm, and the intersection of the axis of the fulcrum axis and the center line in the width direction of the knuckle arm is reduced. A tractor steering device having a length that is approximately half the height that can be changed between a floor specification and a standard specification. 2. The tractor steering system according to claim 1, wherein the tie rod is connected to a lower portion of a knuckle arm in a low floor specification, and is connected to an upper portion of a knuckle arm in a standard specification.