JPH06234374A - Forward-backward inching control device in battery type towing tractor - Google Patents

Abstract

PURPOSE:To provide a forward-backward inclining control device operated at the time of connecting work between a towing tractor and a trailer. CONSTITUTION:Separately from a forward-backward gear operated at a driver's seat, a forward inclining switch 12 and a backward inclining switch 13 that can be operated outside of a vehicle are installed at the rear part of a towing tractor 1. Such a battery type towing tractor is provided with a steering angle sensor 21 for detecting the steering angle of front wheels 2 in the towing tractor 1, a control part 16 for judging whether or not the front wheels 2 are disposed in the rectilinear direction of the towing tractor 1 on the basis of a detection signal from the steering angle sensor 21, and a control part 16 for nullifying the operation of the forward and backward inclining switches 12, 13 in the case of the front wheel 2 not being disposed in the rectilinear direction of the towing tractor 1, on the basis of the judged result from the control part 76.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forward / reverse inching control device for a battery-type towing tractor which is operated when connecting a towing tractor and a trailer.

[0002]

2. Description of the Related Art In a conventional battery-powered towing tractor, as shown in FIG. 7, a forward inching switch 52 and a reverse inching switch 53 that can be operated outside the vehicle are provided separately from the forward / backward traveling device operated at the driver's seat. It is installed at the rear of the towing tractor 51. Then, when the worker gets off the driver's seat with the parking brake released and turns on only the forward or reverse inching switches 52 and 53, the towing tractor 51 moves forward or backward only during the ON operation (inching). It works.

Then, the forward or reverse inching switches 52 and 53 are turned on to operate the towing tractor 51.
By performing an inching operation to the front or the rear, the connecting rod 56 provided at the front end of the trailer 55 is arranged on the bracket 54 provided at the rear of the towing tractor 51. Thereafter, the trailer 55 is connected to the towing tractor 51 by connecting the bracket 54 and the connecting rod 56 with the connecting shaft 57.

[0004]

However, when the parking brake of the towing tractor 51 is stopped in the released state, the front wheels 58, which are steering wheels, are in a tilted state that is not parallel to the longitudinal direction of the towing tractor 51. May be. In this state, when the operator turns on the forward or reverse inching switches 52 and 53, the front wheel 58 is tilted, so that the towing tractor 51 moves forward or backward while bending. Then, the direction changes depending on the steering angle of the front wheels 58, and the moving direction due to the inching operation cannot be predicted. Further, even if the attitude of the towing tractor 51 is adjusted with respect to the trailer 55, there is a problem that the attitude of the towing tractor 51 with respect to the trailer 55 collapses due to this operation.

Therefore, not only the workability when connecting the towing tractor 51 and the trailer 55 is deteriorated, but also
There is a problem that connection work takes time. The present invention has been made to solve the above problems, and an object thereof is to provide an inching control device for forward and backward movement in a battery-type towing tractor that can efficiently perform a connecting operation between a towing tractor and a trailer. Especially.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a forward inching switch which can be operated outside the vehicle, in addition to a forward / backward movement device operated at a driver's seat. In a battery type towing tractor having a reverse inching switch installed in the rear portion of a vehicle body, steering angle detecting means for detecting a steering angle of a steering wheel in the towing tractor, and the steering wheel based on a detection signal from the steering angle detecting means. Is arranged in the straight direction of the towing tractor, and if the steered wheels are not arranged in the straight direction of the towing tractor based on the judgment result from the judging means, the forward and reverse movements are performed. The gist of the present invention is to have an invalidation control means for invalidating the operation of the inching switch.

According to a second aspect of the present invention, in a battery-powered towing tractor in which a forward inching switch and a marching inching switch that can be operated outside the vehicle are installed in the rear part of the vehicle body, in addition to the forward / backward traveling device operated in the driver's seat, Steering angle detection means for detecting the steering angle of the steered wheels in the towing tractor, steering wheel drive means for steering the steered wheels separately from the steering mechanism provided in the towing tractor, and detection from the steering angle detection means Judgment means for judging whether or not the steered wheels are arranged in the straight traveling direction of the towing tractor based on the signal, and the steered wheels are arranged in the straight traveling direction of the towing tractor based on the judgment result from the judging means. If there is not, invalidation control means for invalidating the operation of the forward and reverse inching switches, and When the operation of the forward and reverse inching switches is invalidated by the invalidation control means, the steered wheel correction means for driving the steered wheel drive means to correct the position of the steered wheel so as to be arranged in the straight direction of the towing tractor. The point is to have and.

[0008]

According to the present invention, the steering angle detecting means detects the steering angle of the steered wheels in the towing tractor. The judging means judges whether or not the steered wheels are arranged in the straight traveling direction of the towing tractor based on the detection signal from the steering angle detecting means. Then, when the determining means determines that the steered wheels are not arranged in the straight traveling direction of the towing tractor, the disabling control means disables the operation of the forward or reverse inching switch installed at the rear portion of the vehicle body. Therefore,
The towing tractor does not perform inching operation to the front or the rear. Further, when the determining means determines that the steered wheels are arranged in the straight traveling direction of the towing tractor, the towing tractor performs inching operation forward or backward based on the operation of the forward or reverse inching switch installed at the rear portion of the vehicle body. .

According to another aspect of the present invention, the steering angle detecting means detects the steering angle of the steered wheels of the towing tractor. The judging means judges whether or not the steered wheels are arranged in the straight traveling direction of the towing tractor based on the detection signal from the steering angle detecting means. Then, when the determining means determines that the steered wheels are not arranged in the straight traveling direction of the towing tractor, the disabling control means disables the operation of the forward or reverse inching switch installed at the rear portion of the vehicle body. Therefore, the towing tractor does not perform inching operation to the front or the rear. At that time, the steered wheel correction means steers the steered wheel by the steered wheel drive means, and corrects the steered wheel so as to be arranged in the straight traveling direction of the towing tractor.
When the determination means determines that the steered wheels are arranged in the straight traveling direction of the towing tractor, the operation of the forward or reverse inching switch installed at the rear portion of the vehicle body is validated, and the towing tractor moves forward based on the operation. Alternatively, the inching operation is performed backward.

[0010]

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 1, the towing tractor 1
A front wheel 2 as a steered wheel is provided on the front side, and a rear wheel 3 is provided on the rear side. Further, the driver's seat of the towing tractor 1 is provided with a steering 4 which constitutes a steering mechanism. The steering 4 is connected to a steering mechanism 5, and the steering mechanism 5 is connected to the front wheels 2 via a connecting mechanism (not shown). When the steering 4 is rotated, the steering mechanism 5
Is configured to steer the front wheels 2 through the connecting mechanism based on the amount of rotation of the steering 4.

A traveling motor 6 is provided on the towing tractor 1, and the traveling motor 6 is connected to a transmission 7. The transmission 7 is connected to the rear wheel 3. Therefore, when the traveling motor 6 rotates, this rotation is transmitted to the rear wheel 3 via the transmission 7, and the rear wheel 3
Is designed to rotate. In addition, the traveling motor 6
The forward and reverse rotations cause the rear wheel 3 to rotate normally or reversely so that the towing tractor 1 travels forward or backward.

Further, a towing bar 9 having a connecting hole 8 is provided at the rear of the towing tractor 1. Further, a drawbar 11 having a connecting hole 11a is provided at the front end of the trailer 10. The towing tractor 1 and the trailer 10 are connected by aligning the connecting hole 8 of the towing bar 9 with the connecting hole 11a of the drawbar 11 and inserting a connecting shaft (not shown) in this state.

A forward inching switch 12 and a reverse inching switch 13 are provided at the rear of the towing tractor 1.
And an emergency stop switch 14 are provided. And
When the forward inching switch 12 is turned on, the towing tractor 1 performs an inching operation forward while the forward inching switch 12 is turned on. Similarly, when the reverse movement inching switch 13 is turned on, the towing tractor 1 performs an inching operation backward while the turn-in operation is performed. Furthermore, emergency stop switch 1
4 is turned on, the towing tractor 1 is stopped regardless of whether the forward or reverse inching switches 12 and 13 are turned on.

Further, the towing tractor 1 is provided with a controller 15 for controlling the rotation of the traveling motor 6. Each of the switches 12 to 14 is electrically connected to the controller 15. Further, the controller 15 is connected with a steering angle sensor 21 as steering angle detecting means for detecting the steering angle of the front wheels 2.

The controller 15 drives and controls the traveling motor 6 based on the operation of an accelerator pedal or the like of a forward / backward traveling device (not shown) provided in the driver's seat of the towing tractor 1 to control the traveling direction and traveling speed of the towing tractor 1. It is designed to be controlled or stopped.

Next, the electrical configuration of the controller 15 will be described. As shown in FIG. 2, the controller 15 is a control unit 1 serving as a determination unit and an invalidation control unit.
6, a normal traveling circuit 17, a slow speed forward circuit 18, a slow speed reverse circuit 19, and a regenerative braking circuit 20. Then, the normal traveling circuit 17 drives and controls the traveling motor 6 based on the operation of an accelerator pedal, a direction switching lever and a brake pedal of a forward-reverse traveling device (not shown) to normally drive the towing tractor 1 forward or backward or stop. It is supposed to let you. Further, the slow speed advancing circuit 18 drives and controls the traveling motor 6 so that the towing tractor 1 is inching forward. Further, the slow speed reverse drive circuit 19 drives and controls the traveling motor 6 to perform the inching operation of the towing tractor 1 rearward. The regenerative braking circuit 20 controls the traveling motor 6 by regenerative braking to stop the towing tractor 1.

The control unit 16 is connected to the forward inching switch 12, the reverse inching switch 13 and the emergency stop switch 14, and the steering angle sensor 21.

The control section 16 is adapted to calculate the steering angle of the front wheels 2 based on the detection signal from the steering angle sensor 21. The front wheel 2 is the towing tractor 1.
The control unit 16 determines whether or not it is parallel to the longitudinal direction of the vehicle, that is, whether the front wheels 2 are arranged in the straight traveling direction of the towing tractor 1.

When the controller 16 determines that the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1,
The towing tractor 1 is controlled based on the ON operation of the forward or reverse inching switches 12 and 13.

That is, when only the forward inching switch 12 is turned on, the control section 16 operates the fine speed forward circuit 18 to drive and control the traveling motor 6 only while the forward inching switch 12 is turned on. Then, the towing tractor 1 is adapted to perform an inching operation forward. Further, when only the reverse drive inching switch 13 is turned on, the control unit 16 causes the slow speed reverse drive circuit 1 only while the switch is turned on.
9 is operated to drive and control the traveling motor 6. Then, the towing tractor 1 is adapted to perform an inching operation to the rear.

On the other hand, when the control unit 16 determines that the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1, the forward and reverse inching switches 12, 1 are used.
The ON operation of 3 is invalidated.

That is, even if the forward inching switch 12 or the reverse inching switch 13 is turned on, the control unit 16 does not drive-control the traveling motor 6 via the fine speed forward circuit 18 or the fine speed backward circuit 19. . Therefore, even if the forward or reverse inching switches 12 and 13 are turned on, the towing tractor 1 is not inching forward or backward.

When the emergency stop switch 14 is operated regardless of the states of the other switches 12 and 13, the control unit 1
6 operates the regenerative braking circuit 20 to control the traveling motor 6 by regenerative braking. Then, the towing tractor 1 is immediately stopped.

Next, the operation of the towing tractor 1 configured as described above will be described based on the flowchart shown in FIG. First, the controller 16 of the controller 15
Determines whether or not the emergency stop switch 14 is turned on (STEP 1, hereinafter STEP is simply referred to as S). When the control unit 16 determines that the emergency stop switch 14 is turned on, the control unit 16 shifts to the stop mode, and the control unit 16 does not operate the fine speed forward movement circuit 18 and the fine speed backward movement circuit 19. Therefore, the towing truck 1 is in a stopped state.

Next, when the control section 16 judges that the emergency stop switch 14 has not been turned on, the control section 1
6 is a front wheel 2 based on a detection signal from the steering angle sensor 21.
The steering angle of the front wheel 2 is calculated to determine whether or not the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1 (S).
2). When the control unit 16 determines that the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1, the control unit 16 determines whether or not an accelerator pedal or the like of a forward / backward traveling device (not shown) is operated, that is, the normal traveling mode. It is determined whether to shift to (S3). Then, when it is determined that the accelerator pedal or the like of the forward / backward traveling device is not operated, the control unit 1
6 shifts to the stop mode to bring the towing tractor 1 to a stopped state.

Further, when the control unit 16 determines that the accelerator pedal or the like of the forward-reverse traveling device or the like is operated, the control unit 16 shifts to the normal traveling mode, and the control unit 16 operates the normal traveling circuit based on the depression amount of the accelerator pedal or the like. 17 is operated to drive and control the traveling motor 6. Then, the towing tractor 1 travels based on the operation of the accelerator pedal or the like of the forward-reverse traveling device.

On the other hand, when the controller 16 determines that the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1, the controller 16 determines whether the forward inching switch 12 has been turned on (S4). ). When the controller 16 determines that the forward inching switch 12 is turned on, the controller 16 shifts to the slow forward traveling mode. Then, the control section 16 operates the slow speed forward circuit 18 only while the forward inching switch 12 is turned on to drive and control the traveling motor 6. for that reason,
The towing tractor 1 performs inching operation to the front.

When the controller 16 determines that the forward inching switch 12 has not been turned on, the controller 16 determines whether the backward inching switch 13 has been turned on (S5). When the control unit 16 determines that the reverse drive inching switch 13 is not turned on, the control unit 16 determines whether or not to shift to the normal traveling mode in which the accelerator pedal of the forward / reverse drive device is operated (S6). . When the control unit 16 determines that the accelerator pedal of the forward-reverse traveling device or the like has not been operated, the control unit 16 shifts to the stop mode to stop the towing tractor 1. When the control unit 16 determines that the accelerator pedal of the forward-reverse traveling device or the like is operated, the normal traveling mode is entered and the towing tractor 1 is made to travel.

When the control unit 16 determines in STEP 6 that the reverse drive inching switch 13 is turned on, the control unit 16 shifts to the slow speed reverse drive mode. And
The control unit 16 operates the slow speed reverse drive circuit 19 only while the reverse drive inching switch 13 is turned on to drive and control the traveling motor 6. Therefore, the towing tractor 1 performs inching operation backward.

Therefore, when the towing tractor 1 and the trailer 11 are connected, it is effective to turn on the forward or reverse inching switches 12 and 13 only when the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1. Be converted. On the contrary, when the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1, the ON operation of the forward and reverse inching switches 12 and 13 is invalidated.

Therefore, the front wheels 2 are the towing tractors 1.
When it is not parallel to the longitudinal direction of the towing tractor 1, the towing tractor 1 does not move even if the forward and reverse inching switches 12 and 13 are turned on. As a result, it is possible to reliably prevent the towing tractor 1 from bending and inching forward or backward.

In addition, it is possible to prevent the towing tractor 1 from inclining forward or backward while swinging and to prevent the posture of the towing tractor 1 from collapsing with respect to the trailer 11. As a result, the work of connecting the towing tractor 1 and the trailer 11 can be efficiently performed. [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS.
It will be described based on. The same members as those in the first embodiment and members having the same functions are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment, a steering angle adjusting motor 25 as a steering driving means is connected to the steering mechanism 5 in addition to the steering 4. When the steering angle adjusting motor 25 is driven, the steering mechanism 5 operates and the steering angle of the front wheels 2 can be adjusted via a connecting mechanism (not shown). The steering angle adjusting motor 25 is connected to the controller 15 and driven and controlled by the controller 15.

The controller 15 is provided with a steering correction circuit 26 as steering correction means, and the steering correction circuit 26 drives and controls the steering angle adjusting motor 25. That is, when the forward inching switch 12 or the reverse inching switch 13 is turned on, the control unit 16 calculates the steering angle of the front wheels 2 based on the detection signal from the steering angle sensor 21. Further, the control unit 16 is adapted to judge whether or not the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1.

When the control section 16 determines that the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1,
The ON operation of the forward or reverse inching switches 12 and 13 is invalidated. Then, the control unit 16 operates the steering angle adjustment circuit 26 to operate the steering angle adjustment motor 25.
Is controlled to adjust the steering angle of the front wheels 2 so that the front wheels 2 can be arranged parallel to the longitudinal direction of the towing tractor 1.

When the control section 16 determines that the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1, the fine forward or slow reverse circuit 18, 18 is operated based on the ON operation of the forward or reverse inching switches 12, 13. 19 is operated to drive and control the traveling motor 6.

Next, the operation of the towing tractor 1 configured as described above will be described based on the flowchart shown in FIG. First, the controller 16 of the controller 15
Determines whether or not the emergency stop switch 14 is turned on (STEP 1, hereinafter STEP is simply referred to as S). When the control unit 16 determines that the emergency stop switch 14 is turned on, the control unit 16 shifts to the stop mode, and the control unit 16 does not operate the fine speed forward movement circuit 18 and the fine speed backward movement circuit 19. Therefore, the towing truck 1 is in a stopped state.

Next, the controller 16 determines whether the forward or reverse inching switches 12 and 13 are turned on (S2). And which switch 1
If it is determined that neither 2 nor 13 has been turned on, the control unit 16 shifts to the normal traveling mode. As a result, the control unit 16 operates the normal traveling circuit 17 based on the depression amount of the accelerator pedal or the like of the forward-reverse traveling device to drive and control the traveling motor 6 and cause the towing tractor 1 to travel.

On the other hand, when the control unit 16 determines that the forward or reverse inching switches 12 and 13 are turned on, the control unit 16 determines the steering angle of the front wheels 2 based on the detection signal from the steering angle sensor 21. Calculate (S3). Then, the control unit 16 determines whether the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1 (S4).

When the controller 16 determines that the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1, the controller 16 determines whether the forward inching switch 12 is turned on (S5). . When the control unit 16 determines that the inching switch 12 is turned on, the mode shifts to the slow forward running mode. And
The control unit 16 operates the slow speed forward circuit 17 to drive and control the traveling motor 6 only while the forward inching switch 12 is turned on. Therefore, the towing tractor 1 performs inching operation to the front.

On the other hand, in STEP 4, when the control unit 16 determines that the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1, the control unit 16 causes the steering correction circuit 2 to operate.
6 is operated to drive and control the steering angle adjusting motor 25 (S6). Then, the adjustment is performed until the front wheels 2 are arranged in the straight traveling direction of the towing tractor 1.

When the controller 16 determines that the forward inching switch 12 has not been turned on, the controller 16 determines whether the backward inching switch 13 has been turned on (S7). When the control unit 16 determines that the reverse inching switch 13 is turned on, the mode shifts to the slow speed reverse traveling mode. The control unit 16 operates the slow speed reverse drive circuit 18 to drive and control the traveling motor 6 only while the reverse drive inching switch 13 is turned on. Therefore, the towing tractor 1 performs inching operation backward.

When the control unit 16 determines that the inching switch 12 has not been turned on, the control unit 1
6 determines whether or not the accelerator pedal of the forward / rearward traveling device or the like is operated (S8). When the control unit 16 determines that the accelerator pedal of the forward-reverse traveling device or the like has not been operated, the control unit 16 shifts to the stop mode to stop the towing tractor 1. When the control unit 16 determines that the accelerator pedal of the forward-reverse traveling device or the like is operated, the normal traveling mode is entered and the towing tractor 1 is made to travel.

That is, when the forward or reverse inching switches 12, 13 are turned on, if the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1, the operation is invalidated. Then, the control unit 16 operates the steering correction circuit 26 to drive and control the steering angle adjustment motor 25,
Adjust the steering angle of the front wheels 2. Then, the front wheels 2 are made parallel to the longitudinal direction of the towing tractor 1.

Thereafter, when the forward or reverse inching switches 12 and 13 are turned on again, the control unit 16 operates the fine speed forward circuit 18 or the slow speed reverse circuit 19 based on the ON operation to drive the traveling motor 6. Control. Therefore, the towing tractor 1 performs inching operation to the front or the rear.

Therefore, when the forward or reverse inching switches 12 and 13 are turned on, the steering angle of the front wheels 2 is automatically adjusted even if the front wheels 2 are not parallel to the longitudinal direction of the towing tractor 1 and the front wheels 2 are turned on. Is parallel to the longitudinal direction of the towing tractor 1. Therefore, it is possible to eliminate the need for the operator to purposely rotate the steering wheel 4 to adjust the steering angle of the front wheels 2 so that the front wheels 2 are parallel to the longitudinal direction of the towing tractor 1.

As a result, the connecting work between the towing tractor 1 and the trailer 10 can be performed more efficiently, and the connecting work can be performed in a short time. The front wheel 2
May be provided with an indicator lamp indicating that the front wheel 2 is not arranged in the straight traveling direction of the towing tractor 1, and may be configured to light up when the front wheels 2 are not arranged in the straight traveling direction of the towing tractor 1. As a result, it is possible to confirm whether the towing tractor 1 does not operate due to the failure of the forward inching switch 12 and the reverse inching switch 13, or whether the towing tractor 1 does not operate due to the steering of the front wheels 2.

Further, in the second embodiment, when the front wheels 2 are adjusted so as to be arranged in the straight traveling direction of the towing tractor 1, the display lamp is made to blink, and turned off when the adjustment is completed. It is also possible to do so.

[0050]

As described above in detail, according to the invention described in claim 1, there is an excellent effect that the work of connecting the towing tractor and the trailer can be efficiently performed.

According to the second aspect of the present invention, if the steered wheels of the towing tractor are not arranged in the straight traveling direction of the towing tractor, the adjustment will be performed automatically. Therefore, the connecting work between the towing tractor and the trailer is performed. There is an excellent effect that can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a towing tractor according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of a towing tractor.

FIG. 3 is a flowchart showing a flow of an inching operation.

FIG. 4 is a schematic diagram showing a configuration of a towing tractor according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing an electrical configuration of a towing tractor.

FIG. 6 is a flowchart showing a flow of an inching operation.

FIG. 7 is an explanatory diagram showing a configuration of a towing tractor and a trailer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Towing tractor (vehicle body), 2 ... Front wheels as steered wheels, 12 ... Forward inching switch, 13 ... Reverse inching switch, 16 ... Control part as judgment means and invalidation control means, 21 ... As steering angle detection means Steering angle sensor, 25 ... Steering angle adjusting motor as steering wheel driving means, 26 ... Steering angle adjusting motor as steering wheel correcting means

Claims (2)

[Claims] 1. A battery-type towing tractor having a forward inching switch and a reverse inching switch, which can be operated outside the vehicle, separately from a forward / backward traveling device operated in a driver's seat, and a steering wheel in the towing tractor. Steering angle detecting means for detecting the steering angle of the steering wheel, determining means for determining whether or not the steered wheels are arranged in the straight traveling direction of the towing tractor based on a detection signal from the steering angle detecting means, and the determining means. When the steered wheels are not arranged in the straight traveling direction of the towing tractor based on the determination result from
An inching control device for forward and backward movement in a battery-type towing tractor, comprising an invalidation control means for invalidating the operation of the forward and reverse inching switches. 2. A battery-powered towing tractor having a forward inching switch and a marching inching switch, which can be operated outside the vehicle separately from the forward / backward movement device operated in the driver's seat, installed in the rear part of the vehicle body. Steering angle detecting means for detecting the steering angle of the towing tractor, steering wheel driving means for steering the steered wheels separately from the steering mechanism provided on the towing tractor, and steering based on a detection signal from the steering angle detecting means. When the steering wheel is not arranged in the straight traveling direction of the towing tractor, based on the judgment result from the judgment means, it is determined whether the wheel is arranged in the straight traveling direction of the towing tractor,
Invalidation control means for invalidating the operation of the forward and reverse inching switches, and when the operation of the forward and reverse inching switches is invalidated by the invalidation control means, the steering wheel drive means is driven to operate the steering wheel. An inching control device for forward / backward movement in a battery-type towing tractor, comprising a steering wheel correction means for correcting the position so as to be arranged in the straight traveling direction of the towing tractor.