JPH0577735A - Steering device for carriage - Google Patents

Abstract

PURPOSE:To make steering operation smooth and downsize the construction. CONSTITUTION:In a carriage in which a caster 26 is provided under a frame 20 and a handle 6 is provided rotatably at the end of the frame through a bracket 31, a motor 35 for driving the caster is provided on the bracket. Then two limit switches 41a and 41b and two centering springs 42a and 42b are provided in parallel with each other, respectively, between the supporting member on the bracket side and the handle at any interval. Thus, when the handle is rotated, either one of the limit switches is turned on to drive the motor in the same direction as the handle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a truck equipped with a heavy load, such as a hydraulic jack for supporting the wings of an airplane.

[0002]

2. Description of the Related Art As a bogie of this type, for example, as shown in FIG. 5, a base 20, a hydraulic jack body 9 movably upright in the center of the base 20, and an upper portion of the hydraulic jack body 9 are mounted. In addition, a plurality of retractable legs 15 and 17, casters 26 and 26a provided below the end of the base 20, and a handle provided at the end of the base 20 have been developed.

A steering device for steering the casters 26 is provided on the dolly as described above. As the steering device, for example, the one disclosed in Japanese Utility Model Laid-Open No. 1-178171 is used.

The steering device disclosed in this publication is shown in FIG. That is, the base ends of two steering cylinders 22 and 23 are pivotally attached to the base 20, and the piston rods of the steering cylinders 22 and 23 are attached to the shaft a.
Is connected to the handle 6 side via a bracket b.

A handle 6 which is interlocked with a drive caster 26.
Limit switches LS1, LS2 on both sides of
Is provided and faces the horizontal arm portion of the handle 6.

Upper and lower limit switches LS3 and LS4 are provided at the center of the horizontal arm of the handle 6,
The limit switches LS3 and LS4 are thick contacts 25 and 26 provided on the outer surface of the up-and-down drive cylinder 18 in two upper and lower stages.
Each of them is detachably abutted.

The limit switches LS3 and LS4 are safety switches, and when these switches are turned on, either one of the limit switches LS1 and LS2 is turned on, and can be used without any.

As shown in FIG. 4, the steering cylinders 22 and 23 have oil chambers A and B, respectively, and the oil chambers A and B are selectively connected to the pump P or the tank T via solenoid switching valves 27 and 28. It leads to.

When the steering cylinders 22 and 23 are slightly rotated to the left and right, one of the steering cylinders 22 and 23 is extended to hydraulically assist the rotation of the steering wheel 6 to lighten the steering wheel operation. It is a thing.

Rotate the handle 6 to move the limit switch L
When one of the limit switches LS1 and LS2 is turned on while S3 is in contact with the contact 25, the solenoid switching valve 28 switches to one of the positions to extend and contract one steering cylinder 23.

Similarly, when the limit switch LS4 comes into contact with the contact 26 and one of the limit switches LS1 and LS2 is turned on, the other solenoid switching valve 27 is switched to expand and contract the steering cylinder 22.

When the limit switches LS3 and LS4 are not in contact with the contacts 25 and 26, the solenoid does not operate even when the arm of the handle hits the limit switches LS1 and LS2, and the steering cylinder 22 and
23 remains neutral.

[0013]

In the conventional steering system described above, as shown in FIG. 4, the steering cylinder 23 and the steering cylinder 22 expand and contract within the operating range of R1 and R2, respectively. When the steering cylinder 23 changes from a pushing operation to a pulling operation within the range, the speed of the extension operation becomes faster than that of the pressure operation because of the difference in pressure receiving area between the oil chamber A and the oil chamber B of the steering cylinder 23.

Therefore, there is a problem that a smooth steering operation by the steering wheel 6 cannot be obtained due to the difference in expansion / contraction operating speed.

Further two steering cylinders 22, 2
Since three and two solenoid switching valves 27 and 28, the shaft a and the bracket b are required, the number of parts is large, the structure is complicated, and the assembling is difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a steering apparatus for a trolley which enables smooth steering operation, has a compact structure and can be miniaturized.

[0017]

In order to achieve the above object, the structure of the present invention is a dolly in which a caster is provided at a lower portion of a base and a handle is rotatably provided at an end of the base via a bracket, A motor for driving casters is provided on the bracket, and two limit switches and two centering springs are provided in parallel with each other at an arbitrary interval between the support member on the bracket side and the handle, and one of them is rotated when the handle is rotated. The limit switch is turned on to drive the motor in the same direction as the rotation direction of the handle.

[0018]

When the handle is rotated in one direction against one of the centering springs, one limit switch is turned on and the motor rotates in the direction in which the handle is turned to rotate the caster.

When the rotating operation of the handle is stopped, the restoring force of the centering spring returns the handle to the neutral position. At this time, the limit switch is turned off and the steering operation is stopped.

[0020]

Embodiments of the present invention will be described below with reference to FIGS.

The basic structure of the carriage is the same as the conventional structure shown in FIG. 5, and the same members are designated by the same reference numerals and the detailed description thereof will be omitted.

A base 30 and a bracket 31 are connected to the ends of the base 20 and the legs 15 of the carriage, and a foot base 32 which is vertically movable is provided below the bracket 31.

A housing 33 is provided at the end of the bracket 31.
The handle 6 is rotatably connected via a support plate 34.

A hydraulic motor 35 is provided at the center of the bracket 31.
The output shaft of the hydraulic motor 35 is attached to the drive gear 3 provided in the case 36 above the bracket 31.
It is connected to 7.

The drive gear 37 is a driven gear 3 in the case 36.
8, the driven gear 38 is connected to the caster 26 via the shaft in the housing 33, and when the hydraulic motor 35 rotates in one direction, the drive gear 37, the driven gear 38 and the caster 26 are connected via the shaft. Direction to change the traveling direction of the carriage.

A support plate 34 is rotatably supported by a shaft 43 in the housing 33. A bracket 39 as a supporting member and two handle holders 40 are provided on the supporting plate 34.
a and 40b stand upright, and the base end horizontal portion of the handle 6 is loosely fitted in the handle holders 40a and 40b and rotatably penetrates through.

The handle 6 is extended horizontally outward during traveling or steering operation. When the vehicle is stopped and stored, the handle 6 is rotated counterclockwise as shown in FIG.
0 is folded upwards.

Two limit switches 41a and 41b are provided in parallel on both sides of the bracket 39. The limit switches 41a and 41b face the base end horizontal portion of the handle 6, and the limit switches 41a and 41b are connected to the motor 3 respectively.
Connected to 5.

Therefore, the handle 6 is attached to the holders 40a and 40b.
When the steering operation is performed by swinging in the rotation direction,
For example, if the holder 4 is pressed counterclockwise in FIG.
Since it is loosely fitted to 0a and 40b, it swings slightly counterclockwise and strikes one limit switch 41a, and the limit switch 41a is turned on to rotate the motor 35 and the caster 26 in the same direction as the rotation direction of the handle 6. To do.

Further, between the bracket 39 and the handle 6,
Alternatively, two centering springs 42a and 42b are provided in parallel between the bracket 39 and the holders 40a and 40b.
Always urges the handle 6 to the neutral position. The centering springs 42a and 42b are attached to the holders 40a and 40b.
When facing each other, the holders 40a and 40b can be slightly swung.

Therefore, in order to steer the handle 6 as described above, when the handle 6 is rotated counterclockwise, for example, one of the centering springs 4 is rotated by the handle 6.
When the steering operation is stopped when 2a is compressed, the restoring force of the centering spring 42a causes the handle 6 to move to the position shown in FIG.
Returned to the neutral position.

The steering wheel 6 has a switch 44 for running operation.
a and 44b are provided, and the hydraulic motor 45 for driving the caster 26 is operated by turning on and off the switches 44a and 44b.
Drive or stop. The hydraulic motors 35 and 45 are the base 2
0 is connected to the hydraulic power source.

[0033]

The present invention has the following effects.

Since the motor is used as the drive member of the caster and the limit switch detects the steering operation of the steering wheel to drive the motor, the number of parts is small, the structure is simple and compact, and the assemblability is good. is there.

When the steering wheel of the steering wheel is operated, the motor is started only by turning on the limit switch, so that a large force is not required and a smooth operation can be obtained.

When the steering operation is stopped, the steering wheel can be automatically returned to the neutral position by the centering spring, so that the speedup and the operation force can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a steering device for a truck according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view of FIG. 1 with a handle retracted.

FIG. 4 is a schematic plan view of a conventional steering device.

FIG. 5 is a schematic front view of a truck according to the related art and the present invention.

[Explanation of symbols]

 6 Handle 20 Base 26 Castor 31 Bracket 35 Motor 41a, 41b Limit Switch 42a, 42b Centering Spring

Claims (1)

[Claims] 1. A dolly having casters provided at the bottom of a base and a handle rotatably provided at an end of the base via a bracket, wherein a motor for driving the casters is provided at the bracket, and a bracket-side support member is provided. Two limit switches and two centering springs are installed in parallel with the handle at an arbitrary interval, and when the handle rotates, one limit switch is turned on to drive the motor in the same direction as the handle rotation direction. A steering device for a trolley, which is characterized in that