JPH03258661A - Steering mechanism of elevated spot working vehicle - Google Patents

Abstract

PURPOSE:To make a standard type hydraulic cylinder usable and enhance a reduction in cost by providing such a constitution as interposing a middle arm for rotation at an angle less than 180 deg. between a front wheel steering hydraulic cylinder and a knuckle arm, and connecting the middle arm to the knuckle arm by a drag rod. CONSTITUTION:An elevated working vehicle has a working table disposed on the upper part of a truck 2 through a scissors link type lifting mechanism in such a manner as to be capable of rising and lowering. The truck 2 has lateral pairs of front wheels and rear wheels, in which one is a steering driving wheel 14 and the other is a caster wheel 15, and the steering driving wheels and caster wheels of the front and rear wheels are diagonally disposed. In this case, the piston 5a of a steering hydraulic cylinder 5 for steering the steering driving wheel 14 is pivotally supported by a short middle arm 21 rotating at an angle less than 180 deg., and a drag rod 23 is pivotally fixed to the other end of a long middle arm 22 pivotally supported by a rotating pivot 21a. The drag rod 23 is pivotally fixed to a knuckle arm 24 rotatably by about 180 deg..

Description

[Detailed description of the invention] (a) Industrial application field The present invention is for installing piping and wiring on the interior ceiling after the exterior of a building is completed, or for adding intelligence to the ceiling of an existing building. The present invention relates to a steering mechanism for an aerial work vehicle used when installing a computer communication line.

(B) Prior Art Conventionally, in four-wheeled working vehicles, two diagonal wheels are used as steering drive wheels, and the other two diagonal wheels are used as follower caster wheels, allowing for 360-degree omnidirectional steering. This technology is known to the public.

For example, Japanese Patent Publication No. 41-10249, Japanese Unexamined Patent Publication No. 57
-44'1 Publication, Special Publication No. 1-34166,
This is similar to the technique described in Japanese Patent Publication No. 137294.

(c) Problems to be Solved by the Invention The present invention provides the above-mentioned diagonal two-wheel drive mechanism, in which the front steering drive wheels and the rear steering drive wheels are used as steering wheels, and the front wheel steering hydraulic cylinder and the rear wheel steering cylinder are used as steering wheels. In order to enable the aerial work vehicle to steer freely in narrow spaces, it has two front wheel steering systems and a four-wheel steering system that can also be steered directly to the side. This made it possible.

In order to enable four-wheel steering, i.e., crab steering, which is steering directly to the left and right, both the front and rear steering wheels, which are the steering wheels, must be rotated 180 degrees. It is necessary to be able to rotate the steering, and a typical short stroke hydraulic cylinder
It is not possible to take a stroke that is sufficient to rotate the knuckle arm 180 degrees.

In the present invention, in order to enable the steering drive wheels to rotate 180 degrees using a commercially available standard hydraulic cylinder, an intermediate arm and a drag rod are interposed between the intermediate arms and one of the intermediate arms.
Rotation of 80 degrees or less is approximately 1
The rotation was changed to 80 degrees.

A steering angle detection switch is attached to the pivot shaft 21a of the intermediate arm 21 which rotates by 180 degrees or less.

In addition, if two-wheel front wheel steering and four-wheel steering are possible,
Even when the same forward/reverse operation lever is operated, the direction of travel is completely different between two-wheel steering and four-wheel steering, so an indicator lamp is provided on the display panel to indicate the direction of travel in each case. , the display lamp is switched when switching between front two-wheel steering and four-wheel steering using the steering switching lever 28, and in the case of four-wheel steering, the display lamp is also switched on and lit by switching the steering lever 27 to the left or right. This is the structure that was designed to do so.

In addition, in the case of two-wheel steering in the front wheels, the rear wheels are fixed in a state facing straight in the forward direction, so if only the front wheels are steered and driven in the right and left directions in this state, the steering performance will be improved. Therefore, in the case of two front wheel steering, the stroke of the front wheel steering hydraulic cylinder that operates the trailing caster wheels 15 is adjusted slightly.

(d) Means for Solving the Problems The problems to be solved by the present invention are as described above. Next, the means for solving the problems will be explained.

One of the left and right front wheels that support the truck 2 is used as a steering drive wheel 14, and the other side is used as a following caster wheel 15, and the rear wheel is provided with a following caster wheel 12 at the rear of the steering driving wheel 14, The steering drive wheel 11 is arranged at the rear of the wheel 15, the steering drive wheel and the following caster wheel are arranged diagonally, and each of the steering drive wheels 14 and 11 can be independently steered. A piston 5a of a steering cylinder 5 that steers the direction driving wheels 14 and 11 is pivotally supported on the tip of an intermediate arm 21 that rotates by 180 degrees or less.
A drag rod 23 is pivotally connected to the shaft, and a steering angle detection switch 1 is mounted on a rotational pivot shaft 21a that pivotally supports the intermediate arm 21.
8 has been added.

Further, in a configuration in which the steering operation of the front steering drive wheel 14 and the rear steering drive wheel 11 can be switched between a steering operation of only the two front wheels and a steering operation of the front and rear wheels, a steering switching lever is provided. By switching between two-wheel steering and four-wheel steering using 28, the lighting of the steering direction display lamp provided on the forward/reverse operation lever 20 is switched, and when four-wheel steering is being performed, the steering lever 27 is switched to the left or right. Accordingly, the steering direction indicator lamp is configured to be switched.

In addition, in a configuration in which the steering operation of the front wheel steering drive wheel 14 and the rear wheel steering drive wheel 11 can be switched between a steering operation of only the two front wheels and a steering operation of the front and rear four wheels, the two front wheels In the case of steering, the stroke width of the front wheel steering hydraulic cylinder 5 that steers the front wheel steering drive wheels 14 is regulated to be small.

(E) Embodiment The problems to be solved by the present invention and the means for solving them are as described above.Next, the structure of the embodiment shown in the attached drawings will be explained.

Referring to FIGS. 1, 2, 3, and 4, the overall configuration of the aerial work vehicle will be explained.

The aerial work vehicle of this embodiment has a trolley 2 disposed at the bottom, a workbench 1 at the top, and a scissor link lifting mechanism interposed between the trolley 2 and the workbench 1.

In this embodiment, a three-stage scissor link mechanism is used, in which upper scissor links 8a and 8b, middle scissor links 7a and 7b, and lower scissor links a and 6b are pivotally connected by pins.

In the case of a three-stage scissor link mechanism, the lifting force needs to be strong, so the lifting hydraulic cylinder is
A and two hydraulic cylinders 3a and 3b are arranged, and the two hydraulic cylinders 3a and 3b are expanded and contracted in synchronization by a hydraulic control mechanism.

One link 8b among the upper scissor links 8a and 8b
The upper end of the link 8a is pivoted to the lower part of the workbench 1, and the upper end of the other link 8a bears a roller 10a, and the roller 10a moves back and forth within a guide rail 9a provided on the underside of the workbench 1. It is made to be able to slide.

Similarly, link 6b in lower scissor link roller a.6b
The lower end of the guide rail 9b is pivotally fixed to the trolley 2 by a pin, and the other link 6a has a roller 10b supported by a bearing.
It is fitted in and can be slid back and forth.

In this way, the upper end of one of the upper scissor links 8a, 8b and the lower end of one of the lower scissor links a, 6b are made freely slidable back and forth with respect to the guide rail using rollers, thereby making it possible to raise and lower the scissor link type. The mechanism is made possible.

Figure 1 shows the state in which the hydraulic cylinders 3a and 3b are extended together and the workbench 1 is in the highest position, and Figure 2 shows the hydraulic cylinders 3a and 3b reduced together and a scissor link type lifting/lowering system. The figure shows a state in which the mechanism is folded and the workbench 1 is lowered to the lowest position.

As shown in FIG. 1, an operation box A is provided inside the workbench 1, and by operating the operation panel E of the operation box A, an operator can operate the elevator while standing on the workbench 1. It is possible to do this.

Next, referring to FIG. 4, the devices attached to the trolley 2 will be explained.

There are two batteries B1 and B2 on the left and right in front of the trolley 2.
is mounted, and on the left and right sides of the rear, there is a hydraulic oil tank T for storing hydraulic oil for the hydraulic cylinders 3a and 3b, and a charging station for charging the batteries B1 and B2 with 100 volt commercial power. A container C is placed there.

Since the aerial work vehicle of this embodiment does not have an engine installed, batteries B1 and B2 cannot be automatically charged, so they are charged by charger C from a commercial 100 volt power source when not in use. This is then used as the driving force.

A DC motor M and a hydraulic pump P driven by the DC motor M are mounted as an integrated device at the rear center of the truck 2.

In the overall configuration as described above, four wheels 11, two wheels each, are mounted on the left and right sides of the axle case 30 provided at the front and rear of the truck 2.
・12, 14, and 15 are arranged, and these four wheels are configured into a diagonal two-wheel drive mechanism that drives two diagonal wheels 11 and 14.

As for the front wheels, the right side is a steering drive wheel 14, and the left side is a following caster wheel 15. Although the steering drive wheel 14 is not shown,
It is driven by an independent hydraulic drive motor mf.

The front wheels are steered by expanding and contracting the front wheel steering hydraulic cylinder 5 so that the front steering drive wheels 14 can rotate by 180 degrees around the king pin axis.

0 The rear wheels are steered by the rear wheel steering drive wheel 11 being rotated by 180 degrees around the king pin 25 by expansion and contraction of the rear wheel steering cylinder 4.

The following caster wheels 15 and 12 are not driven by a hydraulic drive motor, nor are they steered by a hydraulic cylinder, and are configured to simply follow the direction of movement of the truck 2 as caster wheels. There is.

In order to make it possible to steer the front steering drive wheels 14 by 180 degrees only by the amount of expansion and contraction of the front wheel steering hydraulic cylinder 5, it is necessary to use a special cylinder with a particularly large stroke of the front wheel steering hydraulic cylinder 5. The cylinder is a normal standard hydraulic cylinder, and a double angle link mechanism is used to connect the cylinder, knuckle arm 24, and rear wheel steering wheel to enable 180 degree steering of the front wheel steering drive wheel 14. It is interposed between the opposite cylinders 4.

That is, as shown in FIG. 5, intermediate arms 21 and 22 are interposed at the tip of the front wheel steering hydraulic cylinder 5, and the tip of the front wheel steering hydraulic cylinder 5 is pivotally supported by the short intermediate arm 21. There is. And on the longer intermediate arm 22,
A drag rod 23 is connected to the drag rod 2
3 is pivotally connected to the knuckle arm 24.

The base of the knuckle arm 24 is fixed to the king pin 25, and as a whole, the front wheel steering hydraulic cylinder 5 does not have a very large stroke, and the long and short intermediate arms 21,
22 can only rotate about 90 degrees, but since the rotation is expanded by the long and short intermediate arms 21 and 22 and transmitted to the knuckle arm 24, the rotation angle of the knuckle arm 24 is 180 degrees. It is possible to rotate.

By the 180 degree rotation of the knuckle arm 24, the steering drive wheel 14 rotates 180 degrees from the 14'' position, through the longitudinally parallel position 14, to the 14' position.

A steering angle detection switch 18 for detecting the steering position of the front steering drive wheel 14 is fixedly installed at a portion of the rotation pivot shaft 2.1a on which the intermediate arms 21 and 22 are pivoted. It is.

Similarly, the steering angle detection switch 19 is also located at the position of the rotation pivot shaft 21a of the intermediate arms 21 and 22 of the rear steering drive wheel 11.
is located.

Therefore, as shown in FIG. 6, switching operation control between two-wheel steering and four-wheel steering is performed by the front steering drive wheels 14 and the rear steering drive wheels 11.

At the beginning of starting 4-wheel steering from 2-wheel front wheel steering,
When the steering switching lever 28 provided on the operation panel E is set to the four-wheel steering position, the rear steering drive wheels 11 are fixed in a parallel state facing forward in the case of two front wheels steering. Therefore, only the front wheel steering driving wheels 14 are operated by operating the front wheel steering hydraulic cylinder 5 using the front wheel steering valve Sf to return the front wheel steering drive wheels 14 to a state parallel to the traveling direction.

When the front wheel steering drive wheel 14 faces in a direction parallel to the traveling direction,
Since the rear wheels naturally face the direction of travel, both the front steering drive wheels 14 and the rear steering drive wheels 11 face forward, and this state is detected by the front wheel steering angle detection switch 18 and the rear wheel steering angle. It is detected by the detection switch 19.

And front and rear front steering drive wheels 14 and rear steering drive wheels 11
When the vehicle stops in a position facing exactly forward, the four-wheel steering lamp 35 lights up, allowing the four-wheel steering state to begin.

When the steering lever 27 is operated from this state, the front steering drive wheels 14 and the rear steering drive wheels 11 rotate in the same left and right directions in an interlocked state.

In addition, the steering switching lever 28 is changed from 4-wheel steering to front 2-wheel steering.
When operating to the wheel steering side, first, the rear wheel steering cylinder 4 is operated by the rear wheel steering valve Sr to return only the rear wheel steering drive wheel 11 to a specified position facing forward, and the rear wheel steering cylinder 4 is returned to that position. When the steering angle detection switch 19 detects this, the two front wheel steering lamps 36 light up, and when the steering switching lever 28 is operated, only the front steering drive wheels 14 are steered left and right.

Due to the two-wheel steering and four-wheel steering, even when the forward/reverse operation lever 20 is operated, the direction of travel is completely different. An indicator lamp is provided to indicate the direction of travel.

That is, in the case of two front wheels steering, either of the two front wheels steering indicator lamps 37C or 38C lights up when the forward/reverse operation lever 20 is operated back and forth, and the steering lever 27
Even if you operate the front two-wheel steering indicator lamp 37C lights up.
・38C does not change.

On the other hand, in the case of four-wheel steering, when the forward/reverse operation lever 20 is operated in the forward direction, the four-wheel steering display lamp 37
/・Both 37r lights up and steering switch lever 2
By operating 8 left or right, the operated side remains lit.

Also, when the forward/reverse operation lever 20 is operated in the reverse direction, 4
When the wheel steering indicator lamp 38°C/38r lights up and the steering switching lever 28 is operated left or right, the four-wheel steering indicator lamp 387 on the side opposite to the direction in which the steering switch is operated!・Since 38r remains lit, this is the forward direction and reverse direction.
This is because even if the four wheels are steered in the same direction, the direction of travel is opposite.

The lift operation lever 50 provided on the surface of the operation panel E switches the lift changeover valve 2 to expand and contract the hydraulic cylinders 3a and 3b, and is constituted by an electromagnetic proportional valve.

7, 8, and 9 show an embodiment in which a hydraulic path for supplying pressure oil to the hydraulic drive motor mr is configured inside the king pin 25.

That is, in the embodiments shown in FIGS. 1 to 6, it is the flexible pipe provided outside that supplies pressure oil to the hydraulic drive motor mr, and when the rear steering drive wheel 11 rotates 180 degrees, The flexible pipe followed this and became 18
It is necessary to bend or twist only 0 degrees, which may cause problems with durability.

In this embodiment, in order to eliminate this problem, 18
An oil passage is provided inside the king pin 25 so that the flexible pipe does not need to be bent by 56 degrees due to 0 degree rotation.

A flexible pipe 31 is connected to the oil passage of the king pin 25.
- 32, and then the oil passage coming out from the king pin 25 is connected to the hydraulic drive motor mr by flexible pipes 33 and 34.

In this configuration, a front wheel drive hydraulic motor m of the front wheel steering drive wheel 14 is provided.
The configuration is similar for f.

Further, in both the first embodiment and the second embodiment, the centers of the steering drive wheels 14 and 11 and the center of the king pin 25 are made to coincide with each other, so that the center of the steering drive wheels 14 and 11 is aligned with the center of the king pin 25. Even if excessive steering rotational force is applied to the tire, since the tire is in contact with the ground at one point, this steering rotational force can be absorbed, and the lack of offset reduces tire wear.

In addition, when switching from two-wheel steering to four-wheel steering, or from four-wheel steering to two-wheel steering, the rear steering drive wheels 11 and the front steering drive wheels 14 are switched stationary. In this case, the center of the tire is aligned with the center of the king pin 25, so that no unreasonable frictional force is generated when turning the wheel. .

Next, this will be explained with reference to the hydraulic circuit diagram in FIG.

The hydraulic pump has a two-pump configuration with Pl and P2, and the pressure oil from the hydraulic pump PL is divided into parts by a flow divider 40 via a flow control valve 39, and is divided into a front wheel steering valve Sf and a rear wheel steering valve. The front wheel steering hydraulic cylinder 5 and the rear wheel steering cylinder 4 are expanded and contracted via Sr.

This constitutes a steering priority circuit that prioritizes steering first.

After the pressure oil necessary for the steering operation is divided and secured, the remaining portion is supplied to the hydraulic circuit for travel and elevation via the flow control valve 39.

In addition, pressure oil from the hydraulic pump P2 is supplied to the elevation switching valve V2 and the speed change switching valve V1 via the 2nd speed switching valve Va.
Pressure oil controlled by the speed change switching valve V1 is supplied to the hydraulic drive motors 7 mf and mr.

The front steering drive wheels 14 and the trailing caster wheels 15 are driven forward and backward by the hydraulic drive motor mf-mr.

Further, pressure oil controlled by the elevation switching valve V2 is supplied to the hydraulic cylinders 3a and 3b via emergency cutoff valves Vb-Vc.

In the above configuration, when four-wheel steering is performed or when the work platform 1 rises above a certain height, the 2nd speed switching valve Va is automatically switched to low speed. -ing

Normally, the cruising 2-speed selector valve Va is switched by the cruising 2-gear selector switch 41 on the display panel E, but during four-wheel steering and lift raising, the cruising 2-speed switching valve Va is automatically switched to the lower speed side. The quick switching valve Va is switched.

Reference numerals 42 and 42 are cocks that are opened when the aerial work vehicle is towed by another towing vehicle.

Furthermore, the circuits of the hydraulic cylinders 3a and 3b are provided with emergency shutoff valves Vb and Vc that stop the lowering and raising in an emergency.

In addition, when the steering mechanism of the aerial work vehicle of the present invention runs, it runs while issuing a warning when traveling, and when traveling at high speed, it emits a high-pitched warning sound, and when traveling at low speed, it emits a high-pitched warning sound, and when traveling at low speed, is designed to emit a low alarm sound.

Further, the front wheel steering valve Sf and the rear wheel steering valve Sr use a simple electromagnetic valve that switches to -, but the elevator switching valve V2 and the speed change switching valve V1 are operated by the elevator operating lever 5.
0 and the shift lever 20 is configured as an electromagnetic proportional valve that supplies pressure oil according to the tilt angle.

FIG. 12 is a main flowchart portion of the steering control mechanism of the aerial work vehicle of the present invention.

As shown in the flowchart, in the case of two-wheel front wheel steering, the front wheel steering angle detection switch 18 first detects whether or not the rear steering drive wheels 11 are at the center position parallel to the direction of travel. If not, a signal is sent to the rear wheel steering valve Sr, and the front wheel steering angle 90 detection switch 18, which also serves as the steering angle detection center, determines the rotation direction from the center, and the rear wheel steering is performed. By switching the rear wheel steering valve Sr in the direction in which the driving wheels 11 are brought to the center, and by expanding and contracting the rear wheel steering cylinder 4,
The rear steering wheel 11 is placed in the center position.

After fixing the rear wheel steering drive tall at the center position, settings are made to limit the turning angle of the front steering drive wheels 14.

According to this setting, the angle is set on the front wheel steering angle detection switch 18 which also serves as a steering angle detection sensor, and when the angle reaches the limit angle, the front wheel steering valve Sf is switched to neutral.

After completing the settings for front two-wheel steering above,
When the wheel steering lamp 36 is turned on and the steering lever 27 is operated left or right, the front wheel steering valve Sf is switched and only the front steering drive wheels 14 are rotated left or right.

At the same time, the front two-wheel steering display lamps 37G and 38c on the forward/reverse operating lever 20 light up, and the forward/reverse operating lever 20 lights up.
Due to the forward and backward rotation of 0, the front two wheel steering indicator lamps 37c and
38c remains lit.

When the steering switching lever 28 is turned on to the four-wheel steering side, it is first detected whether the rear wheel steering drive Vfall is fixed at the center, and if the front operation is two front wheel steering, , since the rear steering wheel 11 is always fixed at the center, after confirming this, the front steering wheel 14
Detects whether it is in the center, and if it is not in the center,
The steering position is detected by the front wheel steering angle detection switch 18,
The front wheel steering valve Sf is switched in the direction to return it to the center, and the front wheel steering drive wheel 14 is moved by expanding and contracting the front wheel steering hydraulic cylinder 5.
Also performs a fixed cut to return it to the center.

Then, when both the rear steering drive wheel 11 and the front steering drive wheel 14 return to the center, the two front wheel steering lamps 36 are turned on, and the four wheel steering display lamps 37g before and after the forward/reverse operation lever 200 are turned on.
・Turn on the 37r and 4-wheel steering indicator lamps 38N and 38r, turn off the other while leaving only one by operating the forward/backward operation lever 20, Only the indicator lamp in the direction of operation remains.

By operating the steering lever 27, both the front wheel steering valve Sf and the rear wheel steering valve Sr are switched synchronously, and the front wheel steering drive wheel 14 and the rear wheel steering drive wheel 11 are rotated in a synchronous state. It will be done.

(F) Effects of the Invention Since the present invention is constructed as described above, it has the following effects.

Since the configuration is as set forth in claim (1), when steering is possible to the left and right, as in crab steering, the front wheel steering drive wheels 1
4 and the rear wheel steering drive wheel 11 require 180 degree steering rotation, and the knuckle arm 24 is rotated by a normal hydraulic cylinder.
If you try to rotate it by 180 degrees, you will need to use a hydraulic cylinder with a considerably long stroke, and because it is a special part, the cost will be high.

However, in the present invention, an intermediate arm 21 that rotates by 180 degrees or less is interposed between the front wheel steering hydraulic cylinder 5 and the knuckle arm 24. By making the tank bottom connected by the drag rod 23, a standard type hydraulic cylinder can be used as the front wheel steering hydraulic cylinder 5 itself, and the cost is reduced.

In addition, in order to enable two-wheel steering and four-wheel steering, it is necessary to once align the positions of the front steering drive wheels 14 and the rear steering drive wheels 11. It is necessary to reliably detect the state in which the front steering drive wheels 14 and the rear steering drive wheels 11 are oriented in the forward direction, but in the present invention, the steering angle detection switch 18 is connected to the intermediate arm 21 By providing this at the rotation pivot shaft 21a, it is possible to reliably detect the matching state of the positions of the front steering drive wheels 14 and the rear steering drive wheels 11.

Since the structure is configured as in claim (2), when the forward/reverse operation lever 20 is operated, the direction of travel is different depending on whether the front wheels are steered with two wheels or the wheels are steered with four wheels. 28 and steering lever 27
In conjunction with the operation of the forward/reverse operation lever 20, the front two-wheel steering indicator lamps 37c and 38C and the four-wheel steering indicator lamp 38
Since the four-wheel steering indicator lamps 37ff and 37r can be switched between n.38r and the four-wheel steering indicator lamps 37ff and 37r, the operator can reliably predict in which direction the vehicle will be steered by operating the forward/reverse operation lever 20 in this state. It has become.

This eliminates the possibility of the aircraft traveling in an unexpected direction and causing personal injury.

With the configuration as set forth in claim (3), in the case of two front wheels steering, the rear steering drive wheels 11 are fixed in a state facing the forward direction and do not perform steering rotation. If the front steering wheel 14 is steered and rotated right sideways in this state,
Since force is applied to the rear steering drive wheels 11 and the steering becomes impossible, in the present invention, when steering two front wheels, the stroke of the front wheel steering hydraulic cylinder 5 is suppressed to a small width. , the rotation width of the front steering drive wheels 14 is suppressed to about 150 degrees.

This allows smooth steering at all times.

[Brief explanation of drawings]

Fig. 1 is an overall side view of an aerial work vehicle equipped with the trend adjustment mechanism of the present invention, Fig. 2 is an overall side view with the work platform 1 lowered, Fig. 3 is a rear view, and Fig. 4 is 5 is a plan view showing the amplification link mechanism of the front steering drive wheel 14, and FIG. 6 is a plan view of the front steering drive wheel 14 and the rear wheel. A drawing showing a control mechanism during two-wheel steering and four-wheel steering of the steering drive wheels 11, FIG. 7 is another embodiment of the rear wheel steering amplification link mechanism and the pressure oil supply mechanism to the hydraulic motor mr. 8 is a sectional view of the king pin 25, FIG. 9 is a side view, FIG. 10 is a plan view of the operation panel E of the operation box A, and FIG. 11 is a cross-sectional view of the king pin 25. FIG. 12, which is an overall hydraulic circuit diagram of the aerial work vehicle, is a flowchart of the steering control mechanism of the aerial work vehicle of the present invention. A...Operation box 5 6 E...Operation panel 1...Work platform 2...Dolly 4...Rear wheel steering cylinder 5...Front wheel steering hydraulic cylinder 11...Operation Direction drive wheel 12...Following caster wheel 18...Front wheel steering angle detection switch 19...Rear wheel steering angle detection switch 20...Forward/forward operation lever 21...Intermediate arm 27...Steering lever 28 ...Steering switching lever 35...Four wheel steering lamp 36...Front two wheel steering lamps 37c, 38c...Front two wheel steering display lamp 387! , 38r, 37j! , 37r...
...Four-wheel steering indicator lamp 7 JP-A-3 258661 (12) Fig. 8 Engraving flat bottom of the drawing 2 years Patent Application 21 Name of invention Steering mechanism for aerial work vehicle 3, Relationship with the amended person case Address name

Claims (3)

[Claims] (1) One of the left and right front wheels supporting the bogie 2 is used as a steering drive wheel 14, the other of the left and right is used as a following caster wheel 15, and the rear wheel is located at the rear of the steering drive wheel 14 as a following caster wheel 1.
2, the steering drive wheel 11 is arranged at the rear of the following caster wheel 15, and the steering drive wheel and the following caster wheel are arranged diagonally, and each steering drive wheel 14 and 11 can be independently steered. In this configuration, the piston 5a of the steering hydraulic cylinder 5 that steers the steering drive wheels 14 and 11 is pivotally supported on an intermediate arm 21 that rotates by 180 degrees or less, and a drag rod 23 is attached to the intermediate arm 21. The steering angle detection switch 18 is pivotally connected to a knuckle arm 24 that rotates about 180 degrees by the drag rod 23, and a steering angle detection switch 18 is attached to a rotational pivot shaft 21a on which the intermediate arm 21 is pivotally supported. A steering mechanism for an aerial work vehicle characterized by being equipped with. (2) The steering operation of the front steering drive wheels 14 and the rear steering drive wheels 11 according to claim (1) is switched to a steering operation of only two front wheels and a steering operation of four front and rear wheels. In this configuration, by switching between 2-wheel steering and 4-wheel steering using the steering switching lever 28, the lighting of the steering direction indicator lamp provided on the forward/reverse operation lever 20 is switched, and furthermore, during 4-wheel steering, A steering mechanism for an aerial work vehicle, characterized in that the steering direction indicator lamp is switched by switching the steering lever 27 to the left or right. (3) The steering operation of the front steering drive wheels 14 and the rear steering drive wheels 11 according to claim (1) is switched to a steering operation of only two front wheels and a steering operation of four front and rear wheels. In a configuration that enables front wheel steering, in the case of two front wheel steering, the front wheel steering drive wheel 14
A steering mechanism for an aerial work vehicle, characterized in that the stroke width of a front wheel steering hydraulic cylinder 5 for steering the vehicle is restricted to a small value.