JP2000025637A - Steering and driving device for traveling vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make operating directions in forwarding and backwarding coincide with each other when a vehicle revolves while the vehicle travels, by simultaneously switching a rotating direction of each movable swash plate of hydraulic pumps of a traveling and driving HST and a steering HST by the operation of a forwarding and backwarding switching operating tool and to prevent the vehicle from being curved in an unintended direction because the operating direction becomes opposite to the sense of an automobile at the time of a backwarding. SOLUTION: This device has a traveling and driving HST constituted of a hydraulic pump and a hydraulic motor, a steering HST and differential devices interlocked and connected with each output shaft of each hydraulic motor. A movable swash plate of a hydraulic pump of the traveling and driving HST is linked with a transmission pedal, a movable swash plate of a hydraulic pump of the traveling and driving steering HST 22 is linked with a steering wheel 14, a control arm 74 connected with each movable swash plate is connected to a link 115 switching each rotating direction and this link 115 is linked with a forwarding and backwarding switching and operating tool 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention connects two HSTs, one for steering and the other for traveling, by driving a pair of left and right axles to perform steering and traveling driving, The present invention relates to a technique for matching the speed change operations of both HSTs in forward and reverse.

[0002]

2. Description of the Related Art Conventionally, two HST-type transmissions are connected left and right, an axle is projected from each HST-type transmission to both sides, and wheels are fixed to ends of both axles. A technique for changing the angle of a swash plate of a transmission to drive left and right wheels is known. For example, the technology of US Pat. No. 4,782,650. In this technique, when traveling straight, the traveling speeds of the left and right HSTs are the same, and when turning, the traveling speeds of the left and right wheels are different.

[0003]

However, in the conventional traveling vehicle, unless the output rotations of the left and right HST transmissions are completely matched, the vehicle cannot go straight, it takes time for adjustment at the time of shipment, and there are also errors in parts and assembly. It was necessary to increase the precision by making it smaller. Also, if there is a difference in capacity between the hydraulic pump and the hydraulic motor, the right and left turning feelings are different, and the traveling vehicle is very difficult to steer. Also,
When working while turning, the conventional traveling vehicle has a large turning radius.For example, when performing a small turn such as lawn mowing around a grove, it is necessary to travel the same position many times. The work efficiency was getting worse.

[0004]

The present invention uses the following means to solve the problems. That is, the traveling drive HST including the hydraulic pump and the hydraulic motor and the steering HS
T, a differential gear operatively connected to the output shaft of each hydraulic motor, and a pair of left and right axles operatively connected to the two differential gears are housed in one housing. Also, the vehicle has a traveling drive HST and a steering HST composed of a hydraulic pump and a hydraulic motor, and a differential device that is connected to the output shaft of each hydraulic motor in an interlocked manner. In cooperation with the adjustment member, the movable swash plate of the hydraulic pump of the steering HST is linked with the steering operation tool, and the control arm connected to each of the movable swash plates is connected with a link for switching the rotation direction, and the link is connected to the control arm. This is linked with the forward / reverse switching operation tool. Further, a guide member is provided on each of the control arms, a control shaft serving as a rotation fulcrum of the control arm is provided near the center of the guide member, and one end of a swing link is engaged with the guide member, and the swing The other ends of the links are respectively linked to a speed adjusting member and a steering operation tool, and a middle portion of each swing link is linked to a forward / reverse switching operation, and the guide member is an elongated hole.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problems and means to be solved by the present invention are as described above. Next, an embodiment in which the present invention shown in the attached drawings is applied to a mower will be described. 1 is an overall side view of a mower employing the steering drive of the present invention, FIG. 2 is a plan view of the steering drive, FIG. 3 is a side sectional view of the same, FIG. 4 is a plan sectional view of the same, and FIG. FIG. 6 is a skeleton diagram showing another embodiment of the steering drive system, FIG. 7 is a side view showing a linking mechanism between the control arm of the traveling drive HST and the speed change pedal, and FIG. It is a side view which shows the cooperation mechanism of a control arm, a steering handle, and a forward / reverse switching lever.

Referring to FIG. 1, the entire structure of a lawn mower 1 equipped with a steering drive according to the present invention will be described. Vehicle chassis 1
A front column 13 is erected on a front portion of the vehicle 2, and a steering handle 14 is projected from the front column 13 as a steering operation tool. The front column 1
A shift pedal 15 as a shift operating tool, a forward / reverse switching lever 5 as a forward / backward switching operating tool, and a brake pedal (not shown) are disposed on the side of the reference numeral 3. On both front lower sides of the vehicle chassis 12, front wheels 16, 16 which are caster wheels serving as driven wheels, are arranged. In this embodiment, the front wheels 16 are arranged at two places on the left and right. However, one wheel may be arranged, or three or more wheels may be arranged. By using the front wheel 16 as a caster wheel, when turning around the rear wheel at the time of turning, which will be described later, the front wheel 16 turns more easily and quickly in the turning direction than when it is connected to the steering wheel. It can move and improve the steering feeling.

A seat 17 is mounted on the center of the vehicle chassis 12, and a mower 9 is disposed below the mower 9. The mower 9 is provided with a rotary blade in a case 19, and is provided with a pulley, a belt, and the like from an engine 11 described later. It is configured to be driven via a.
Further, the mower 9 can be moved up and down on the front part and the rear part of the case 19 by being connected to link mechanisms for elevating and lowering, respectively.
An engine 11 is mounted on a rear portion of the vehicle chassis 12 and covered with a bonnet. The engine 11 is a vertical type, and an output shaft 11a projects vertically downward, and an output pulley 20 is fixed to a lower end of the output shaft 11a. Has been established.

[0008] The steering drive device 2 of the present invention is arranged at a lower rear portion of the vehicle chassis 12. As shown in FIGS. 2, 3, and 4, the steering drive device 2 includes a traveling drive HST21 including a hydraulic pump and a hydraulic motor and a steering HST22 in a single housing 23.
, A differential device including a differential gear device, and a pair of left and right axles 40L and 40R are housed. However, traveling drive HS
The position of T21 and the steering HST22 for steering may be reversed.

A first input shaft 25 and a second input shaft 26 serving as pump shafts of the traveling drive HST 21 and the steering HST 22 respectively protrude above the housing 23. A first input pulley 27, a second input pulley 28, and fans 39, 39 are fixedly mounted thereon, and the output pulley 20 and a tension pulley 29 are disposed between the first input pulley 27 and the second input pulley 28. , The first input pulley 27
The belt 30 is wound between the second input pulley 28, the output pulley 20, and the tension pulley 29, so that power can be transmitted from the engine 11.

A pulley 3 is further provided on the first input shaft 25.
As shown in FIG. 1, a support pipe 32 is erected at an intermediate portion of the vehicle chassis 12 in the front-rear direction, and a counter shaft 33 is rotatably supported on the support pipe 32 so as to be rotatable. Pulleys 34 at the top and bottom of 33 respectively
35 is fixedly mounted, the pulley 34 and the pulley 31
The belt 37 is wound between the pulley 35 and the pulley 38 fixed on the input shaft of the mower 9 to drive the mower 9. However, a tension pulley may be disposed between the pulley 35 and the pulley 38 to provide a belt tension clutch so that the driving force of the mower 9 can be connected and disconnected.

Next, the structure inside the housing 23 will be described with reference to FIGS. 3, 4 and 5. FIG. The traveling drive HST21, the steering HST22, the traveling differential 6, the steering differential 7, the axles 40L and 40R, and the power transmission gear mechanism are housed in a housing 23 configured to be vertically splittable.
Since the configuration of the traveling drive HST21 and the steering HST22 are substantially the same, the configuration of the traveling drive HST21 will be described. The traveling drive HST 21 has a hydraulic pump 52 arranged on a horizontal portion of an L-shaped center section 51 having a horizontal portion and a vertical portion, and a hydraulic motor 53 mounted on the vertical portion.
And a hydraulic motor 53 beside the hydraulic pump 52.
And the hydraulic pump 52 and the hydraulic motor 53 are fluidly coupled by a closed circuit formed in the center section 51.

The housing 23 is formed by joining each other on a peripheral flat joint surface in a horizontal plane, and a bearing portion for the motor shaft 54 and the counter shaft 55 is provided on the joint surface of the housing 23. Axle 40L ・ 40
The bearing portion of R is displaced upward from the joint surface and rotatably supported. Each of the axles 40L and 40R is differentially coupled by a differential gear device 56, and both ends protrude to the left and right outside of the housing.

The hydraulic pump 52 includes a center section 5.
1, an input shaft 25 serving as the pump shaft is vertically supported at the center thereof,
A cylinder block is fitted to the input shaft 25 and is disposed so as to be rotatable and slidable on a surface provided with a pump, and a plurality of pistons are fitted in the cylinder block via a biasing spring so as to be reciprocally movable. A movable swash plate 57 is in contact with the head of. By tilting the movable swash plate 57 as a speed adjusting member, the amount and direction of oil discharge from the hydraulic pump 52 can be changed.

In order to tilt the movable swash plate 57,
A control shaft 59 is axially supported on the side wall of the housing 23 in parallel with the axle 40 (FIG. 2). A neutral return spring is fitted inside the housing of the control shaft 59 so that the movable swash plate 5
7 is biased to the neutral position so that the neutral position can be adjusted. A control arm 60 is fixed on a control shaft 59 outside the housing 23, and a speed change operation tool such as a lever or a pedal is provided via a link mechanism described later.
In this embodiment, it is connected to the speed change pedal 15. The speed of the speed change pedal 15 can be increased according to the amount of depression.

With the above construction, the control arm 6 is rotated by rotating the speed change pedal 15.
0 is rotated in the longitudinal direction of the aircraft, and the control shaft 5
The rotation of the movable swash plate 57 is tilted by the rotation of the cylinder 9 so that the discharge direction and discharge amount of the hydraulic oil from the hydraulic pump 52 can be changed.

Pressure oil from the hydraulic pump 52 is supplied to a hydraulic motor 53 via an oil passage in the center section 51. The structure of the hydraulic motor 53 is the center section 5
A motor-attached surface is formed on the vertical surface of the motor 1. The cylinder block 63 is rotatably supported on the motor-attached surface. A plurality of pistons 64 are fitted in the plurality of cylinder holes of the cylinder block 63 via biasing springs so as to be reciprocally movable. The head of the piston 64 is in contact with the fixed swash plate 65. A hydraulic motor 53 is formed by integrally and horizontally disposing a motor shaft 54 on the rotation axis of the cylinder block 63 so as not to rotate relatively.

A brake device 66 is provided on the motor shaft 54.
A gear 67 is fixed to the end of the motor shaft 54, and the gear 67 meshes with a large-diameter gear 68 fixed on the counter shaft 55. Further, a small-diameter gear 69 fixed on the counter shaft 55 meshes with a ring gear 70 of the differential gear device 56, and is decelerated from the motor shaft 54 by the ring gear 70.
Is driven to transmit power to the left and right axles 40L and 40R.

The steering HST 22 has substantially the same configuration as the traveling drive HST 21, is disposed substantially symmetrically in the front-rear direction, and includes a hydraulic pump 71 and a hydraulic motor 72. A control shaft 73 for rotating the movable swash plate 76 of the hydraulic pump 71 protrudes to the right of the housing 23, and is connected to a control arm 74 fixed on the control shaft 73 outside the housing via a link mechanism described later. The movable swash plate 76 is rotated by the rotation of the steering handle 14.

A brake device 78 is disposed at the end of the motor shaft 77 of the hydraulic motor 72 so that the arm 79 can be rotated to perform braking. Also,
A gear 80 is fixedly mounted on the motor shaft 77.
Is meshed with a gear 82 on a counter shaft 81, and a gear 83 fixed on the counter shaft 81 is meshed with a ring gear 84 of the steering differential 7 composed of a differential gear device. The differential output shaft 41L of the steering differential 7
Output gears 90L and 90R are fixed on both sides of 41R, and a gear 92L fixed on the axle 40L via a counter gear 91 on one side (left side in this embodiment) of the output gears 90L and 90R. The other gear 90R meshes with a gear 92R fixed on the axle 40R.

In such a configuration, the traveling drive HST2
The driving force from the first hydraulic motor 53 is gears 67, 68.6.
The speed is reduced to 9 and transmitted to the ring gear 70 of the traveling differential 6 to drive the axles 40L and 40R. Further, when the hydraulic motor 72 of the steering HST 22 is operated, the driving force is reduced to the gears 80, 82, 83, and transmitted to the ring gear 84 of the steering differential 7, so that the differential output shaft 4
Power is transmitted to 1L / 41R, but in order to transmit rotational forces in opposite directions to gears 92L / 92R fixed on axles 40L / 40R, one side is in the deceleration direction and the other side is in the acceleration direction. By transmitting the torque, the left and right wheels (rear wheels 43.4)
The rotation difference is generated in 3), and the aircraft can be turned.

Further, instead of using the two differential gear type differentials, the steering can be similarly driven by using a planetary gear and a bevel gear shown in FIG. That is, as shown in FIG. 6, the output rotation of the hydraulic motor 53 is reduced and the axle 4
The gear 93 meshes with a center gear 94 fixed on a shaft 93 disposed on the same axis as the 0L / 40R. Sun gears 95 are fixed on both sides of the shaft 93, and the outer periphery of the sun gear 95 A plurality of planetary gears 96 are engaged with each other, and the planetary gears 96 are supported by carriers 97. The carriers 97 are fixed to the inner ends of the axles 40L and 40R. I have. The outside of the planetary gears 96 is further meshed with the internal gears 98.
98 is a gear 99/99 loosely fitted on the axle 40L / 40R.
And is fixed integrally.

On the other hand, a bevel gear 100 is fixed to a motor shaft 77 of the hydraulic motor 72, and bevel gears 102, 102 fixed to the bevel gear 100 on support shafts 101, 101.
Gears 103 are fixed to the outside of the support shafts 101, and the gears 103 are engaged with the gears 99. With such a configuration, when the output rotation from the hydraulic motor 72 is transmitted from the bevel gear 100 to the bevel gears 102 and 102, the output rotation is rotated in opposite directions to each other. The deceleration rotation is transmitted to the other side, and the vehicle can turn.

At this time, when the output rotations of the hydraulic motors of the traveling drive HST 21 and the steering HST 22 are adjusted to the rightward and leftward turning directions by the rotation of the steering handle 14, the movable swash plate 57 on the traveling drive side is moved backward. If the steering wheel 14 is similarly rotated to rotate, the steering wheel 14 turns in the opposite direction. In other words, the vehicle turns in a direction opposite to the direction in which the vehicle turns while moving backward. Therefore, the present invention, as shown in FIGS.
The speed change pedal 15 and the control arm 60;
A link mechanism for interlocking the steering handle 14 and the control arm 74 is further provided.
It is linked and linked.

That is, the control arm 60 has a plate formed in a substantially triangular shape, one end of the control shaft 59 is fixed to the top of the center, and the other side of the control arm 60 has an arcuate shape serving as a guide member. A long hole 60a is opened, and a pin 108 provided at one end of the swing link 105 is slidably inserted into the long hole 60a. The other end of the swing link 105 is pivotally supported by one end of a connecting rod 106, and a middle part of the swing link 105 is pivotally connected to a lifting rod 107. The lifting rod 107 is connected to one end of an interlocking wire 109. The other end of the link wire 109 is connected to the forward / reverse switching lever 5. A spring 110 is interposed between the swing link 105 and the connecting rod 106, and urges the swing link 105 to rotate upward or downward beyond the dead center. However, the spring force of the spring 110 is smaller than the spring force of the neutral return spring. Also,
An intermediate portion of the connecting rod 106 is slidably supported by a boss 111 or the like, and the other end of the connecting rod 106 is connected to a long hole of an arm 112 protruding from the base of the speed change pedal 15.

In such a configuration, when the forward / reverse switching lever 5 is switched to the forward side, the interlocking wire 10
9 is pulled, the swing link 105 is rotated upward, and the pin 108 is held at the upper advanced position 60F.
When the shift pedal 15 is depressed in this state, the connecting rod 10
6. When the swing link 105 is pushed, the control arm 60 is rotated counterclockwise, and the movable swash plate 57 is rotated only in the forward direction. Conversely, when the forward / reverse switching lever 5 is switched to the reverse side, the interlocking wire 109 is pushed, and the swing link 105 is rotated downward, and
Is held at the lower reverse position 60R. When the shift pedal 15 is depressed in this state, the connecting rod 106, the swing link 1
When 05 is pressed, the control arm 60 is rotated clockwise in the opposite rotation direction, and the movable swash plate 57 is rotated only in the reverse direction. However, a configuration in which the swing arm 105 is pulled to rotate the control arm 60 is also possible.

As shown in FIG. 8, the control arm 74 of the steering HST 22 has a plate formed in a substantially triangular shape, one end of the control shaft 73 is fixed at a substantially central portion, and the other end of the control arm 74 is provided. An arc-shaped long hole 74a serving as a guide member is opened in the side portion, and a pin 118 provided at one end of the swing link 115 is connected to the long hole 74a.
a is slidably inserted into a. The upper portion of the long hole 74a is the forward position 74F, the lower portion is the reverse position 74R, the central portion is the neutral position 74N, and the neutral position 74N has a long hole 74b that can slide in the radial direction.

The other end of the swing link 115 is pivotally supported by one end of a sliding rod 116, and an intermediate portion of the swing link 115 is pivotally connected to a lifting rod 117, which branches from the interlocking wire 109. Are connected. The other end of the interlocking wire 109 is connected to the forward / reverse switching lever 5, and an engaging portion 109a for the detent mechanism 119 is provided in the middle of the interlocking wire 109 to rotate the forward / backward switching lever 5 to the neutral position. When you do, you can hold in that position. Further, a spring 120 is interposed between the swing link 115 and the sliding rod 116 to urge the swing link 115 to rotate upward or downward beyond the dead center. However, the spring force of the spring 120 is smaller than the spring force of the neutral return spring, and the detent mechanism 1
19 is smaller than the holding force.

A middle portion of the sliding rod 116 is slidably supported by a boss 121 or the like.
The other end of 6 is connected to the rack 122 via a link, an arm, or the like. The rack 122 is engaged with a pinion 123 provided at a base of the steering handle 14.

In such a configuration, when the forward / reverse switching lever 5 is switched to the forward side, the interlocking wire 10
9 is pulled, the swing link 115 is rotated upward, and the pin 118 is held at the upper forward position 74F.
When the steering handle 14 is rotated in this state, the sliding rod 116 and the swing link 115 are pushed and pulled,
The control arm 74 is rotated left and right to move the movable swash plate 7.
6 also rotates in the forward or reverse direction, and can be turned.

Conversely, when the forward / reverse switching lever 5 is switched to the reverse side, the interlocking wire 109 is pushed, the swing link 115 is rotated downward, and the pin 118 is moved to the lower reverse position 74R. Will be retained. When the steering handle 14 is rotated in this state, the sliding rod 116 and the swing link 105 are pushed and
Is rotated left and right in the opposite direction to the above, and the movable swash plate 76 is also rotated in the forward or reverse direction, so that it can be turned.
In this way, the control arm 74 moves forward and backward.
By changing the rotation direction of the vehicle, the vehicle can be driven by operating the steering wheel 14 in the same manner as an automobile even if the vehicle turns while moving backward.

When the forward / reverse switching lever 5 is in a neutral state, the swing link 105 is located between the forward position and the reverse position, and the control arm 60 is rotated even when the shift pedal 15 is depressed. The swing link 115 is located at the center in the vertical direction, and when the steering handle 14 is turned, the pin 118 moves in the long hole 74b to turn the control arm 74. Therefore, the hydraulic motor 72 is not driven, the axle 40 is not driven, and the vehicle does not move forward or backward, thereby improving safety. However, the present invention is not limited as long as it guides a pin of a swing link such as a guide rail instead of the long holes 60a and 74a.

[0032]

According to the present invention, the following effects can be obtained by the configuration described above. That is, in the first aspect, the traveling drive HST including the hydraulic pump and the hydraulic motor is provided.
And a steering HST, a differential device operatively connected to the output shafts of the respective hydraulic motors, and a pair of left and right axles operatively connected to the two differential devices are housed in one housing. The housing containing the driving HST and the steering HST can be integrally attached to the vehicle chassis, so that a compact driving mechanism can be configured, and moreover, it can be mounted on a small traveling vehicle. Also, because it is housed in one housing,
It can be easily assembled to the vehicle chassis, requires only one oil reservoir, and can reduce costs.

According to a second aspect of the present invention, a traveling drive HST including a hydraulic pump and a hydraulic motor and a steering HS
T and a differential device operatively connected to the output shafts of the respective hydraulic motors. The movable swash plate of the hydraulic pump for the traveling drive HST is linked to a speed adjusting member, and the movable swash plate of the hydraulic pump for the steering HST is connected. The plate is linked to a steering operation tool, and a link for switching the rotation direction is connected to a control arm connected to each of the movable swash plates, and the link is linked to a forward / reverse switching operation tool. The rotating direction of each movable swash plate of the hydraulic pump of the steering HST can be switched simultaneously by operating the forward / reverse switching operation tool, and when turning while traveling, the operating directions can be matched between forward and backward. This makes it possible to reverse the direction of operation of the vehicle when the vehicle is moving backward, making it difficult to drive and turning in an unintended direction.

According to a third aspect of the present invention, a guide member is provided on each of the control arms, and a control shaft serving as a pivot of the control arm is provided near the center of the guide member, and one end of the swing link is connected to the guide member. And the other end of the swing link is linked with the speed adjusting member and the steering operating tool, and the middle part of each swing link is linked with the forward / reverse switching operation. In addition, the structure of the linkage between the steering arm and the speed adjusting member and the control arm is simplified, and the structure of the linkage with the forward / reverse switching operation is also simplified. Therefore, forward and backward switching and steering direction switching can be performed at low cost.

In the fourth aspect, since the guide member is formed as a long hole, the guide member can be easily formed only by forming a hole, and the control arm can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is an overall side view of a mower employing a steering drive device of the present invention.

FIG. 2 is a plan view of a steering drive device.

FIG. 3 is a side sectional view of the same.

FIG. 4 is a plan sectional view of the same.

FIG. 5 is a skeleton diagram of a steering drive system.

FIG. 6 is a skeleton diagram showing another embodiment of the steering drive system.

FIG. 7 is a side view showing a link mechanism between a control arm of the traveling drive HST and a speed change pedal.

FIG. 8 is a side view showing a link mechanism of a control arm of the steering HST, a steering handle, and a forward / reverse switching lever.

[Explanation of symbols]

 2 Steering drive device 5 Forward / reverse switching lever 11 Engine 14 Steering handle 15 Speed change pedal 21 Traveling drive HST 22 Steering HST

Continued on the front page F term (reference) 3D040 AA02 AA22 AB04 AC01 AC12 AC17 AC24 AC28 AC30 AC43 AC50 AD02 AD12 AD15 AE19 AF10 3D042 AA01 AA06 AB11 BA02 BA05 BA07 BA08 BA10 BA13 BA20 BB01 BB03 BC01 BD02 BD04 BD08 BD09 A0301 A05 EE02 EE04 FF01 GG03 HH01 JJ00 JJ08 JJ10 JJ21 JJ35 3J067 AA12 AA27 AB01 AC42 AC53 AC55 BA04 BB07 CA24 CA32 DA02 DA03 DA07 DA12 DA14 DA22 DA72 FB61 FB81 FB83 GA12

Claims (4)

[Claims] 1. A driving device HST comprising a hydraulic pump and a hydraulic motor, a steering HST, a differential device operatively connected to an output shaft of each hydraulic motor, and a left and right device operatively connected to the two differential devices. A steering drive device for a traveling vehicle, wherein a pair of axles are housed in one housing. 2. A traveling drive HST and a steering HST comprising a hydraulic pump and a hydraulic motor, and a differential device which is operatively connected to an output shaft of each hydraulic motor.
The movable swash plate of the hydraulic pump of the traveling drive HST is linked to a speed adjusting member, the movable swash plate of the hydraulic pump of the steering HST is linked to a steering operation tool, and a control arm connected to each of the movable swash plates. A steering drive device for a traveling vehicle, wherein a link for switching a turning direction is connected, and the link is linked to a forward / reverse switching operation tool. 3. A guide member is provided on each of the control arms, a control shaft serving as a fulcrum of rotation of the control arm is provided near the center of the guide member, and one end of a swing link is engaged with the guide member. 3. The operation of a traveling vehicle according to claim 2, wherein the other end of the swing link is linked to a speed adjusting member and a steering operating tool, respectively, and a middle portion of each swing link is linked to a forward / reverse switching operating tool. Drive. 4. The steering drive device for a traveling vehicle according to claim 3, wherein the guide member is an elongated hole.