JP2003104178A - Vehicular body lifting and holding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a overhanging cylinder from expanding even when a selector valve is erroneously operated. SOLUTION: This vehicular body lifting and holding device 20 is composed of overhanging beams capable of overhanging in a vehicular width direction by overhanging cylinders 24, plural outrigger devices 21 having a jack equipped to a tip end portion of the overhanging beam and capable of virtually expanding and contracting by a jack cylinder 27, plural selector valves 31 to 34 provided corresponding to the outrigger devices 21 and selectively supplying oil into the overhanging cylinders 27 and the jack cylinders 24, a coming/going switching valve 39 controlling supplying/discharging the oil to/from the selector valve, double pilot check valves 67 arranged in second oil passages 48 connecting the selector valves and bottom chambers 27a of the jack cylinders 27 and in a third oil passage 49 connecting a rod chamber 27b of the jack cylinder and the coming/going switching valve 39, and a pilot check valve 61 arranged in a sixth oil passage 52 and a seventh oil passage 53 communicating to the second oil passage 48 and the third oil passage 49.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body lifting support device, and more particularly, to a projecting beam that can project and enter in the vehicle width direction, and is attached to the tip of the projecting beam to expand and contract vertically. The present invention relates to a vehicle body lifting support device including a plurality of movable jacks and provided with a plurality of outrigger devices arranged on a side portion of a vehicle body.

[0002]

2. Description of the Related Art An aerial work vehicle uses an aerial work device mounted on a vehicle body to move a workbench to a desired height position so that an operator on the workbench can perform aerial work. Thus, when the workbench is moved to a high place in this manner, the moment in the falling direction acting on the vehicle body increases, and the vehicle body support is likely to become unstable. For this reason, in the conventional aerial work vehicle, it is configured to have a projecting beam that can project and move in the vehicle width direction, and a jack that is attached to the tip end of the projecting beam and that can be expanded and contracted vertically. Some are equipped with a vehicle body lifting support device having a plurality of outrigger devices arranged on the side of the vehicle body.

As shown in FIG. 10, this vehicle body lifting support device includes a plurality of outrigger devices 21 and an outrigger device 2.
1, selector valves 31, 32, 33 and 34 for selectively supplying oil to the overhanging cylinder 27 and the jack cylinder 24, and oil from a hydraulic pump (not shown). Selector valves 31, 3
2, 33, and 34 are provided with an inlet / outlet switching valve 39 for controlling the supply and discharge. The inlet / outlet switching valve 39 and the selector valves 31, 32, 33, 34 are connected by the first oil passage 47, and the selector valves 31, 32, 33, 34 and the bottom chamber 27a of the jack cylinder 27 are connected by the second oil passage 48, and the jack The rod chamber 27b of the cylinder 27 and the entrance / exit switching valve 39 are connected by a third oil passage 49. In addition, the selector valves 31, 32, 33, 34 and the overhanging cylinder 24.
Bottom chamber 24a is connected by a fourth oil passage 50, and rod chamber 24b of overhang cylinder 24 and third oil passage 49 are connected by fifth oil passage 51.
Are connected by.

Pilot check valves 65 and 66 are provided corresponding to the second oil passage 48 and the third oil passage 49, respectively. These pilot check valves 65,
Reference numeral 66 allows the oil flow to the jack cylinder 27 side, restricts the oil flow to the selector valves 31, 32, 33, 34 side and the inlet / outlet switching valve 39 side, and at the same time, the second oil passage 48 and the third oil passage 48. When the pilot pressure of the oil passage on the upstream side of the pilot check valves 65, 66 arranged on the upstream side of the oil flowing in the oil passage 49 is received, the pilot check valves 65, 66 arranged on the downstream side are opened. A so-called double pilot check valve 67 that allows the flow of oil to the selector valves 31, 32, 33, 34 side and the inlet / outlet switching valve 39 side is configured.

With such a vehicle body lifting support device, as shown in FIG.
Jack 27 of the outrigger device 21 indicated by arrow A in 0
In order to make the jack extend and ground the jack, first, the operation lever 34a of the selector valve 34 is operated to the jack side. Then, the operation lever 39a of the access switching valve 39 is operated to the extension side. When this operation lever 39a is operated to the extension side, the oil discharged from the hydraulic pump (not shown) causes the oil in / out switching valve 39, the selector valve 34 and the second oil passage 4 to flow.
It is supplied to the bottom chamber 27a of the jack cylinder 27 through the reference numeral 8. At the same time, the pilot check valve 66 arranged in the third oil passage 49 receives the pilot pressure in the second oil passage 48 and opens. As a result, the jack cylinder 27 extends. When the jack is grounded and the operation lever 39a of the access switching valve 39 is operated to the neutral position, the oil supply to the jack cylinder 27 is cut off, and the jack is maintained in the grounded state.

[0006]

The operator selects a selector valve 31 different from the selector valve 34 described above.
When the operating lever 31a (for example, the valve indicated by arrow B in FIG. 10) is erroneously operated to the extension side, the second oil passage 48
Oil pressure in the second oil passage 48 closer to the selector valve 34 than the pilot check valve 65 disposed in the third oil passage 49, and the third oil pressure in the inlet / outlet switching valve 39 side relative to the pilot check valve 66 disposed in the third oil passage 49. When the oil pressure in the oil passage 49 is high, the double pilot check valve 65 may be opened and the second oil passage 48 and the third oil passage 49 may be in a communication state.

In such a case, the oil in the second oil passage 48 is
The first operated selector valve 34, the first oil passage 47, the erroneously operated selector valve 31, and the erroneously operated selector valve 31 pass through the fourth oil passage 50 that connects the erroneously operated selector valve 31 and the extension cylinder 24 shown by the arrow C in FIG. It is supplied to the bottom chamber 24a of the discharge cylinder 24. On the other hand, this overhang cylinder 24
Since the pilot check valve 66 arranged in the third oil passage 49 is open, the rod chamber 24b of
Is in communication with the rod chamber 27b of the jack cylinder 27 of the outrigger device 21. As a result, the extension cylinder 24 and the jack cylinder 27 form a closed circuit,
There is a problem that the jack cylinder 27 is contracted and the extension cylinder 24 is expanded even though the entrance / exit switch 39 is in the neutral state.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle body lifting support device which does not extend and retract the overhang cylinder and the jack cylinder even if the selector valve is erroneously operated. .

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, a vehicle body lifting support device according to the present invention comprises an extension beam that can be extended in the vehicle width direction, and a protrusion beam that projects the extension beam in the vehicle width direction. A plurality of cylinders that are arranged on the side of the vehicle body and that are configured to have an overhanging cylinder, a jack that is attached to the tip of the overhanging beam, and that is vertically expandable and retractable, and a jack cylinder that expands and contracts the jack. And a plurality of cylinder selection valves (for example, selector valves 31, 32, 33 in the embodiment, which are provided corresponding to the outrigger devices and which selectively supply oil to the overhanging cylinder and the jack cylinder, respectively. 34) and a cylinder drive control valve (for example, an implementation) that controls the supply and discharge of oil from a hydraulic supply source (for example, the hydraulic pump P in the embodiment) to the cylinder selection valve. And out switching valve 39 in the state)
A first oil passage connecting the cylinder drive control valve and the cylinder selection valve, a second oil passage connecting the cylinder selection valve and the bottom chamber of the jack cylinder, a rod chamber of the jack cylinder and the cylinder drive control valve Third to connect with
An oil passage, a fourth oil passage connecting the cylinder selection valve and the bottom chamber of the extension cylinder, and a fifth oil passage connecting the rod chamber of the extension cylinder and the third oil passage, and a second oil passage. And a pilot check valve corresponding to each of the third oil passages. The pilot check valve allows the oil flow to the jack cylinder side and allows the oil flow to the cylinder selection valve side and the cylinder drive control valve side. Regulate and second
When the pilot pressure of the oil passage on the upstream side of the pilot check valve arranged on the upstream side of the oil flowing through the oil passage and the third oil passage is received, the pilot check valve arranged on the downstream side opens to select the cylinder. In a vehicle body lifting support device having a double pilot check valve configured to allow the flow of oil to the valve side and the cylinder drive control valve side, the cylinder drive control valve becomes a cylinder selection valve in a neutral state. Of the second oil passage and the third oil passage when the cylinder drive control valve is switched to the neutral state. It has a sixth oil passage 52, a seventh oil passage 53, and a pilot check valve 61).

According to the vehicle body lifting support device having the above structure, the cylinder selection valve is operated to the jack side, oil is supplied to the jack cylinder of the outrigger device via the cylinder drive control valve, and the jack is extended and grounded. When the cylinder drive control valve is switched to the neutral state and a cylinder selection valve different from the first operated cylinder selection valve is accidentally operated to the extension side,
The hydraulic pressures in the second oil passage and the third oil passage are in a reduced state.
Therefore, the double pilot check valve provided in the second oil passage and the third oil passage connected to the extended jack cylinder is in a state in which the oil flow to the cylinder selection valve side and the cylinder drive control valve side is restricted. ,as a result,
Even if the second oil passage connected to the extended jack cylinder communicates with the bottom chamber of the extension cylinder connected to this through the erroneously operated cylinder selection valve, the hydraulic pressure to extend this extension cylinder Does not work. Also, the second
Since the contraction movement of the jack cylinder is restricted by the pilot check valve arranged in the oil passage, the oil in the rod chamber of the overhanging cylinder does not flow out to the jack cylinder side. Therefore, it is possible to prevent the jack cylinder from contracting and the extension cylinder from expanding.

In the vehicle body lifting support device having the above-mentioned structure, the pressure reducing means connects the first oil passage and the tank, and includes the sixth oil passage having the first throttle, the third oil passage and the tank. And a pilot line to a seventh oil passage having a second throttle, and an eighth oil passage that is arranged in the sixth oil passage and the seventh oil passage and connects the oil supply source and the cylinder drive control valve. , A third throttle in the pilot line, and receives the pilot pressure of the oil flowing in the eighth oil passage through the pilot line to release the regulation of the oil flow to the tank side, thereby making the second oil passage and the third oil passage. It may be configured to have a pilot check valve that allows the oil therein to flow into the tank through the sixth oil passage and the seventh oil passage.

According to the vehicle body lifting support system having the above structure, when the cylinder drive control valve is switched to the neutral state,
The pilot check valve receives the pilot pressure of the oil flowing in the eighth oil passage and releases the restriction of the oil flow in the sixth oil passage and the seventh oil passage to the tank side. Therefore, the second oil passage and the third oil passage are communicated with the tank through the sixth oil passage, the seventh oil passage, and the pilot check valve, and as a result, the oil pressure in the second oil passage and the third oil passage is reduced. In a high state, this hydraulic pressure can be reduced with a simple structure.

In the vehicle body lifting support system having the above-mentioned structure, the pressure reducing means includes a neutral detecting means (for example, the neutral position sensor 75 in the embodiment) for detecting whether or not the cylinder drive valve is in the neutral state, and the first The sixth oil passage connecting the oil passage and the tank, the seventh oil passage connecting the third oil passage tank, the sixth oil passage and the seventh oil passage are arranged. The oil passage opening / closing valve (for example, the electromagnetic valve 71 in the embodiment) that communicates or shuts off, and the oil passage opening / closing valve is operated when the neutral detection means detects that the cylinder drive valve is in the neutral state. It may be configured to include a valve operation control unit (for example, the controller 73 in the embodiment) that connects the passage and the seventh oil passage.

According to the vehicle body lifting support device having the above structure, when the cylinder drive control valve is switched to the neutral state,
The valve operation control means actuates the oil passage opening / closing valve, and the oil passage opening / closing valve brings the sixth oil passage and the seventh oil passage into a communicating state.
Therefore, the second oil passage and the third oil passage communicate with the tank via the sixth oil passage, the seventh oil passage, and the oil passage opening / closing valve, and as a result, the hydraulic pressure in the second oil passage and the third oil passage is increased. If is high, this hydraulic pressure can be reliably reduced. It should be noted that the valve operation control means operates the oil passage opening / closing valve to open the sixth oil passage and the seventh oil passage only for a predetermined time (time for pressure to be released) after the cylinder drive control valve is switched to the neutral state. You may make it a communication state.

Further, the vehicle body lifting support device according to the present invention has an extension beam which can be extended in the vehicle width direction, an extension cylinder which allows the extension beam to project and enter in the vehicle width direction, and a tip of the extension beam. A plurality of outrigger devices, each of which has a jack that is attached to a vehicle part and that can be expanded and contracted vertically, and a jack cylinder that expands and contracts the jack, are provided on the left and right of the vehicle body. A cylinder drive control valve having a plurality of cylinder selection valves for selectively supplying oil to the outlet cylinder and the jack cylinder, and a cylinder drive control valve for controlling supply / discharge of oil from a hydraulic pressure supply source to the cylinder selection valve. Oil passage connecting the cylinder selection valve and the cylinder selection valve, a second oil passage connecting the cylinder selection valve and the bottom chamber of the jack cylinder, and a rod chamber of the jack cylinder A third oil passage connecting the cylinder drive control valve, a fourth oil passage connecting the cylinder selection valve and the bottom chamber of the extension cylinder, and a fifth oil passage connecting the rod chamber of the extension cylinder and the third oil passage. And a pilot check valve respectively corresponding to the second oil passage and the third oil passage. The pilot check valve allows the oil flow to the jack cylinder side, and drives the cylinder selection valve side and the cylinder. When the flow of oil to the control valve side is regulated and the pilot pressure in the oil passage upstream of the pilot check valve arranged upstream of the oil flowing in the second oil passage and the third oil passage is received, Double pilot check valve configured to open the pilot check valve disposed on the side to allow the flow of oil to the cylinder selection valve side and the cylinder drive control valve side. In the vehicle body lifting support device including the above, the cylinder drive control valve is configured to cut off the supply of oil to the cylinder selection valve in the neutral state, and the fifth oil passage includes the rods of the plurality of overhanging cylinders. A rod connecting oil passage connecting the chambers, and a communicating oil passage communicating with the rod connecting oil passage and connected to the third oil passage,
A pilot line is connected to the eighth oil passage that is arranged in the communication oil passage and that connects the oil supply source and the cylinder drive control valve, and allows the oil flow to the overhang cylinder side to allow the oil to flow to the cylinder drive valve side. Pilot check valve that regulates the flow and regulates the flow of oil to the cylinder drive valve side even if the pilot pressure of the oil flowing through the eighth oil passage is received via the pilot line when the cylinder drive valve is in the neutral state Have.

According to the vehicle body lifting support device having the above-described structure, the cylinder selection valve is operated to the jack side, and oil is supplied to the jack cylinder of the outrigger device via the cylinder drive control valve, and the jack extends and grounds. When the cylinder drive control valve is switched to the neutral state and a cylinder selection valve different from the first operated cylinder selection valve is accidentally operated to the extension side,
The flow of oil from the fifth oil passage to the third oil passage is blocked. Therefore, the second oil passage connected to the extended jack cylinder communicates with the bottom chamber of the extension cylinder connected to the erroneously operated cylinder selection valve, and the extension cylinder is extended and hydraulic pressure acts in the direction. However, since the fifth oil passage connected to the rod chamber of the extension cylinder is closed, it is possible to prevent the extension movement of the extension cylinder. Further, since the oil does not flow from the fifth oil passage to the third oil passage, it is possible to prevent the extension movement of the jack cylinder from contracting.

Further, the vehicle body lifting support device according to the present invention has a bulging beam that can project and move in the vehicle width direction, and a jack that is attached to the tip of the bulging beam and that can move up and down vertically. A plurality of outrigger devices disposed on the side of the vehicle body, and a cylinder selection valve provided corresponding to each outrigger and selectively supplying oil to the overhang cylinder and the jack cylinder, A cylinder drive control valve that controls the supply and discharge of oil from a hydraulic pressure supply source to the cylinder selection valve, and the cylinder selection valve is a selection lever that can be tilted back and forth from a neutral position (for example, the operation lever 31a in the embodiment, 32a, 33a, 3
4a), when the selection lever is tilted back and forth from the neutral position, oil can be supplied to the overhang beam or the jack in accordance with the operation, and the cylinder drive control valve moves forward and backward from the neutral position. A tiltable drive lever (for example, the operation lever 39a in the embodiment) is provided, and when the drive lever is tilted back and forth from the neutral position, oil is supplied to the overhanging beam or jack selected by the cylinder selection valve. In the vehicle body lifting support device, when the selection lever is tilted from the neutral position to one of the front and rear sides, the tilt operation of the other selection lever to the other side of the front and rear is restricted, and the front and rear operation of the drive lever is performed. It has a lever operation restricting means that enables it.

According to the vehicle body lifting support device having the above structure, when the selection lever is tilted from the neutral position to either the front or rear side, the lever operation restricting means causes the other selection lever to move to the other side. The tilting operation is regulated and the drive lever can be operated back and forth. Therefore, it is possible to prevent the situation in which the selection levers are operated in a mixed state on either one of the front and rear sides and the other side from the neutral position.
Further, since the drive lever can be always tilted back and forth, the jack and the projecting beam can be operated according to the tilting direction of the selection lever. Furthermore, when the selection lever tilted to the front side and the selection lever tilted to the rear side coexist, even though the cylinder drive control valve does not control the oil supply / discharge, Even in a vehicle body lifting support device in which the extension movement of the vehicle body is extended, it is possible to reliably prevent the extension movement of the extension cylinder simply by mounting the lever operation restricting means on the vehicle body lifting support device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS. The present embodiment shows a mode of an aerial work vehicle having a work platform at the tip of a boom which is constructed so that it can be undulated and swung on the vehicle body and can be expanded and contracted.

[0020]

First Embodiment First, before explaining a first embodiment of a vehicle body lifting / supporting device according to the present invention, an aerial work vehicle equipped with the vehicle body lifting / supporting device will be described. As shown in FIG. 1, the aerial work vehicle 1 is configured with a truck vehicle as a base, has a driving cabin 5 in the front portion of the vehicle body 3, and has a turning cabin built in the vehicle body 3 in the rear portion of the vehicle body 3. A swivel base 7 is provided which is driven by a motor (not shown) and is capable of horizontally swiveling. A boom 9 pivotally connected to the base end is attached to the upper part of the swivel base 7.
Is a base boom 9a, a middle boom 9b, and a tip boom 9c.
Telescopic cylinder 11 with a built-in combination of
It is configured to be expanded and contracted by. The boom 9 is configured to be capable of hoisting and lowering by a hoisting cylinder 13.
A work table 15 which is held in a horizontal state regardless of the hoisting motion of the boom 9 is attached to the tip of the tip boom 9c.

Next, the vehicle body lifting support device will be described with reference to FIGS. 2 to 5. Vehicle body lifting support device 20
Is configured to include an outrigger device 21 that is provided on both left and right sides of the vehicle body on the vehicle rear side of the driving cabin 5 to lift and support the vehicle, and an operation device 30 that operates the drive of the outrigger device 21. ing. Outrigger device 2
Reference numeral 1 denotes an overhanging beam 23 which is arranged on both left and right sides of the vehicle body rearward of the driving cabin 5 in front of and behind the vehicle body so as to be able to overhang in the vehicle width direction. An extension cylinder 24 to be moved, and a jack 26 attached to the tip of the extension beam 23 and vertically movable.
And a jack cylinder 27 that extends and retracts the jack 26.
And is configured. The jack 26 includes an outer post 26a vertically attached to the tip end portion of the overhanging beam 23, an inner post 26b configured to be capable of protruding into the outer post 26a, and an outer post 26a built in these posts. The above-mentioned jack cylinder 27 that causes the inner post 26b to move in and out with respect to
And is configured.

An operating device 30 for operating the drive of the outrigger device 21 is arranged at the rear part of the vehicle and is provided with four selector valves 31, 32, 33, 34 and one entrance / exit switching valve 3.
9 and 9. On the front surface of the operating device 30, there are five operating levers 31a, 32a, 33a, 34a, 3
A panel 43 having a through hole 41 through which the bases of all levers 9a are inserted is provided. Selector valves 31, 3
2, 33, and 34 are provided corresponding to the outrigger devices 21, respectively, and have a function of selectively supplying oil to the overhanging cylinder 24 and the jack cylinder 27, and have a 6-port 3-position manual detent The operation lever 31 is a switching valve and can be tilted back and forth from the neutral position.
a, 32a, 33a, 34a. When the operation levers 31a, 32a, 33a, 34a are tilted to either the front or rear side, the selector valves 31, 32, 3
3, 34 supply oil to the jack cylinder 27,
When the operation levers 31a, 32a, 33a, 34a are tilted to either the front or rear side, the selector valve 31,
32, 33 and 34 are configured to supply oil to the overhanging cylinder 24.

On the other hand, the inlet / outlet switching valve 39 is a hydraulic pump P.
It is a switching valve with a manual detent with 6 ports and 3 positions, which has a function of controlling the supply and discharge of oil from the selector valves 31, 32, 33, 34, and the aforementioned operating lever that can be tilted back and forth from the neutral position. 39a. When this operation lever 39a is tilted to either the front or rear side,
The in-and-out switching valve 39 supplies oil in a direction to extend the jack cylinder 27 or the overhanging cylinder 24, and when the operating lever 39a is tilted to the other side of the front and rear, the in-and-out switching valve 39 moves the jack cylinder 27 or the overhanging side. It is configured to supply the oil in the direction in which the cylinder 24 is contracted.

As shown in FIG. 4B, the four selector valves 31 to 34 and the entrance / exit switching valve 39 are arranged in the vehicle width direction, and are arranged on the leftmost side (the lower side of FIG. 4). ) Is a valve corresponding to the outrigger device 21 arranged on the front left side of the vehicle, and the selector valve 32 arranged on the right side of the selector valve 31 is arranged on the rear left side of the vehicle. The valve corresponding to the installed outrigger device 21 and arranged on the right side of the selector valve 32 (the valve at the central portion) is the in / out switching valve 39. Further, the selector valve 33 arranged on the right side of the entrance / exit switching valve 39 is a valve corresponding to the outrigger device 21 arranged on the front right side of the vehicle, and the selector valve 34 arranged on the right side of the selector valve 33.
Is a valve corresponding to the outrigger device 21 disposed on the right rear side of the vehicle.

Here, the selector valve 34 and the entrance / exit switching valve 39 of the outrigger device 21 arranged on the right rear side of the vehicle.
A hydraulic circuit including will be described with reference to FIG. As shown in FIG. 3, the selector valve 39 is connected to the inlet / outlet switching valve 39 via a first oil passage 47, is connected to the bottom chamber 27a of the jack cylinder 27 via a second oil passage 48, and is further connected to a fourth chamber. Bottom chamber 2 of overhanging cylinder 24 via oil passage 50
It is connected to 4a. The inlet / outlet switching valve 39 is connected to the rod chamber 27b of the jack cylinder 27 via the third oil passage 49, and is connected to the hydraulic pump P via the eighth oil passage 54. The rod chamber 24b of the overhanging cylinder 24 is connected to the third oil passage 49 via the fifth oil passage 51. Pilot check valves 65 and 66 are provided corresponding to the second oil passage 48 and the third oil passage 49, respectively, and the pilot check valves 65 and 66 allow the oil to flow toward the jack cylinder 27 side. The flow of oil to the selector valve 34 side and the inlet / outlet switching valve 39 side is regulated, and more than the pilot check valves 65 and 66 arranged upstream of the oil flowing through the second oil passage 48 and the third oil passage 49. A double pilot check valve that allows the pilot check valves 65 and 66 disposed on the downstream side to open when receiving the pilot pressure of the oil passage on the upstream side to allow the oil flow to the selector valve 34 side and the inlet / outlet switching valve 39 side. It constitutes 67.

Further, the first oil passage 47 and the tank T have a first
The sixth oil passage 52 having the throttle 56 is connected to the third oil passage 4
The seventh oil passage 53 having the second throttle 57 between the tank 9 and the tank T
Are connected. The sixth oil passage 52 and the seventh oil passage 53 join together on the tank T side to form one oil passage.

The combined sixth oil passage 52 and seventh oil passage 53
Is provided with a pilot line 60 connected to the eighth oil passage 54 and having a third throttle 58. The pilot pressure of the oil flowing in the eighth oil passage 54 is received via the pilot line 60 to the oil on the tank T side. Is provided with a pilot check valve 61 for releasing the flow restriction.

The hydraulic circuit of the outrigger device 21 arranged on the front right side of the vehicle, the hydraulic circuit of the outrigger device 21 arranged on the left rear side of the vehicle, and the hydraulic circuit of the outrigger device 21 arranged on the front left side of the vehicle are described above. Since this is based on the hydraulic circuit of the outrigger device 21 arranged at the right rear of the vehicle, the same reference numerals are given to the same aspect parts and the description thereof will be omitted. As a result, the four selector valves 31 to 34 and the entrance / exit switching valve 39 form the hydraulic circuit shown in FIG. In the hydraulic circuit shown in FIG. 2, an unload valve 63 is provided in the eighth oil passage 54 through which the oil discharged from the hydraulic pump P flows. This valve returns excess oil to the tank T so as to maintain the hydraulic pressure in the eighth oil passage 54 at a predetermined pressure when the inlet / outlet switching valve 39 is set to the neutral state and the oil supply / discharge control is stopped. It has a function.

In the vehicle body lifting support device 20 having the above-described structure, as shown in FIG. 2, the jack of the right rear outrigger device 21 (outrigger device 21 shown by the arrow A in FIG. 2) is extended and grounded. To do so, first, the operation lever 34a of the selector valve 34 is operated to the jack side (upper side in FIG. 2). Then, the operation lever 39a of the access switching valve 39 is operated to the extension side (upper side in FIG. 2). When the operating lever 39a is operated to the extension side, the oil discharged from the hydraulic pump P is supplied to the eighth oil passage 54, the inlet / outlet switching valve 39, and the first oil passage 54.
It is supplied to the bottom chamber 27 a of the jack cylinder 27 through the oil passage 47, the selector valve 34 and the second oil passage 48. At the same time, the pilot check valve 66 arranged in the third oil passage 49 receives the pilot pressure in the second oil passage 48 and opens. As a result, the third oil passage 49 is brought into communication with the rod oil chamber 27 of the jack cylinder 27.
The oil in b can flow out to the tank T through the third oil passage 49 and the inlet / outlet switching valve 39, and the jack cylinder 27 extends. Then, when the jack 26 disposed at the rear right of the vehicle shown in FIG. 1 extends and comes into contact with the ground, and the operation lever 39a of the entry / exit switching valve 39 is operated to the neutral position, the oil supply to the jack cylinder 27 is cut off. The jack 26 is maintained in the grounded state.

In this state, for example, the operator mistakenly operates the operation lever 31a of the selector valve 31 (for example, the valve indicated by the arrow B in FIG. 2) different from the selector valve 34 described above, on the protruding side (the lower side in FIG. 2). ). Here, when the operation lever 31a is operated to the extension side, the hydraulic pressure in the second oil passage 48 closer to the selector valve 34 than the pilot check valve 65 arranged in the second oil passage 48, and the third The third on the side of the inlet / outlet switching valve 39 side from the pilot check valve 66 arranged in the oil passage 49
When the oil pressure in the oil passage 49 is high, the double pilot check valve 66 is opened and the second oil passage 48 and the third oil passage 48 are opened.
The oil passage 49 may be in a communication state.

In such a case, the oil in the second oil passage 48 is
The selector cylinder 34 operated first, the first oil passage 47, the erroneously operated selector valve 31, and the fourth oil passage 50 connected to the erroneously operated selector valve 31 are passed through the bulging cylinder 24 connected to the fourth oil passage 50 (see FIG. 2 is supplied to the bottom chamber 24a of the cylinder (indicated by arrow C). On the other hand, the rod chamber 24b of the overhanging cylinder 24 has a pilot check valve 66 (arrow D in FIG. 2) disposed in the third oil passage 49.
Valve) indicated by the arrow A, the rod chamber 2 of the jack cylinder 27 of the outrigger device 21 indicated by the arrow A is indicated.
It is in a state of communicating with 7b. As a result, the overhanging cylinder 24 and the jack cylinder 27 form a closed circuit, and the jack cylinder 27 contracts and the overhanging cylinder 2 moves even though the in-and-out switching valve 39 is in the neutral state.
4 expands. That is, the outrigger device 21 operates against the will of the operator who operates the operating device 30.

However, in the vehicle body lifting support device 20 according to the present invention, when the entrance / exit switching valve 39 is switched to the neutral state, the unload valve 63 reduces the hydraulic pressure in the eighth oil passage 54, and as a result, The pilot check valve 61 arranged in the sixth oil passage 52 and the seventh oil passage 53 operates so as to regulate the flow of oil to the tank T side, but this is prevented by the third throttle 58 provided in the pilot line 60. The hydraulic pressure reduction speed between the throttle 58 and the pilot check valve 61 is slowed down. Therefore, there is a time lag between the time when the inlet / outlet switching valve 39 is switched to the neutral state and the time when the pilot check valve 61 completely shuts off the oil flow to the tank T side. As a result, during this time, the oil in the second oil passage 48 and the third oil passage 49 remains in the sixth oil passage 5
2, flowing out to the tank T through the seventh oil passage 57 and the pilot check valve 61, and the second oil passage 48 and the third oil passage 4
The oil pressure in 9 decreases. Therefore, the double pilot check valve 67 arranged in the second oil passage 48 and the third oil passage 49 connected to the extended jack cylinder 27 (corresponding to the outrigger device 21 indicated by the arrow A) is
The flow of oil to the selector valve side 34 and the inlet / outlet switching valve 39 side is regulated. As a result, the extension cylinder 24 in which the second oil passage 48 connected to the extended jack cylinder 27 is connected to the erroneously operated selector valve 31.
Even if it communicates with the bottom chamber 24a of the cylinder (indicated by arrow C), the hydraulic pressure for extending the extension cylinder 24 does not act on the extension cylinder 24. In addition, since the contraction movement of the jack cylinder 27 is restricted by the pilot check valve 65 arranged in the second oil passage 48, the overhang cylinder 24 is prevented.
The oil in the rod chamber 24b does not flow out to the jack cylinder 27 side. Therefore, it is possible to prevent the jack cylinder 27 from contracting and the extension cylinder 24 from expanding.

In the above-described embodiment, the case where the selector valve 31 corresponding to the outrigger device 21 in the front left of the vehicle is erroneously operated has been described. However, the present invention is not limited to this. Even when the corresponding selector valves 33, 32 are erroneously operated, the same effect as in the case described above is obtained.

Further, in the above-described embodiment, the pilot check valve 6 is provided in the sixth oil passage 52 and the seventh oil passage 53.
However, as shown in FIG. 5, an electromagnetic valve 71 may be provided instead. The electromagnetic valve 71 is a 3-port 2-position switching valve, and when the solenoid 71a is energized, the sixth oil passage 52 and the seventh oil passage 53 are brought into communication with each other to allow the oil flow to the tank T side. , Solenoid 71a
Is de-energized, the sixth oil passage 52 and the seventh oil passage 53
To shut off the flow of oil to the tank T side.
The operation control of the electromagnetic valve 71 is performed by the controller 73. In / out switching valve 3 for controller 73
9 is electrically connected to the neutral position sensor 75, and the controller 73 receives the neutral signal from the neutral position sensor 75 indicating that the access switching valve 39 is in the neutral position. 71a
Is configured to be excited.

With this structure, when the inlet / outlet switching valve 39 is switched to the neutral state, the hydraulic pressure in the second oil passage 52 and the third oil passage 53 is reduced as in the case of the pilot check valve 61 described above. Therefore, it is possible to prevent the jack cylinder 27 from contracting and the extension cylinder 24 connected to the erroneously operated selector valve 31 from expanding. Further, the neutral position sensor 75 detects the neutral state of the input / output switching valve 39, and the electromagnetic valve 71 operates according to the information from this sensor, so that the opening control of the second oil passage 52 and the third oil passage 53 can be performed reliably and reliably. It can be done quickly. The controller 7
3 indicates that the electromagnetic valve 71 is operated and the sixth oil passage and the seventh oil passage are brought into communication with each other for a predetermined time (time for pressure to be released) from the time when the entry / exit switching valve 39 is switched to the neutral state. May be. By doing so, it is possible to prevent the extension cylinder 24 from extending when the extension cylinder 24 receives a force in the extension direction.

[0036]

Second Embodiment Next, a second embodiment of the vehicle body lifting support device 20 will be described. In the second embodiment, only the differences from the first embodiment will be described, and the same portions as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 6, the fifth oil passage 51
Is a rod connection oil passage 51 that connects between the rod chambers 24b of the respective extension cylinders 24 of the four outrigger devices 21.
a and the third oil passage 4 by communicating with the rod connecting oil passage 51a.
9, and a communication oil passage 51b connected to No. 9.
In the communication oil passage 51b, a pilot line 77 is connected to the eighth oil passage 54 to allow the oil flow to the extension cylinder 24 side, regulate the oil flow to the inlet / outlet switching valve 39 side, and switch the inlet and outlet. No. 8 when the valve 39 is in the neutral state
A pilot check valve 79 is provided for restricting the flow of oil to the entrance / exit switching valve 39 side even if the pilot pressure of oil flowing through the oil passage 54 is received via the pilot line 77.

According to the vehicle body lifting support device 20 having the above-mentioned structure, the selector valve 34 corresponding to the outrigger device 21 on the right rear side of the vehicle is operated to the jack side, and the outrigger indicated by the arrow A is supplied with oil via the inlet / outlet switching valve 39. The jack 26 shown in FIG. 1 is supplied to the jack cylinder 27 of the device 21.
When the selector valve 31 that is different from the selector valve 34 that was operated first is erroneously operated to the extension side when the input / output switching valve 39 is switched to the neutral state, the The oil pressure in the eighth oil passage 54 decreases and the pilot check valve 79 causes the fifth oil passage 5
The flow of oil from 1 to the third oil passage 49 is shut off. Therefore, the second oil passage 48 connected to the extended extension jack cylinder 27 of the outrigger device 21 shown by arrow A communicates with the bottom chamber 24a of the overhanging cylinder 24 shown by arrow C connected to the erroneously operated selector valve 31. Even if the hydraulic pressure in the direction of extending the extension cylinder 24 acts on the extension cylinder 24, the fifth oil passage 51 connected to the rod chamber 24b of the extension cylinder 24 is in the closed state. The extension movement of the overhanging cylinder 24 can be restricted. Also,
Since the oil does not flow from the fifth oil passage 51 to the third oil passage 49, the contraction movement of the jack cylinder 27, which is the extension movement of the outrigger device 21 shown by the arrow A, can be restricted.

As described above, in the vehicle body lifting support device 20 of the second embodiment, the hydraulic pressures in the second oil passage 48 and the third oil passage 49 are changed when the entrance / exit switching valve 39 is switched to the neutral state. Even if it is high, do not reduce this oil pressure,
It is configured to regulate the extension movement of the overhang cylinder 24. For this reason, means for lowering the hydraulic pressure is not required, and the configuration of the hydraulic circuit can be simplified.

[0039]

[Third Embodiment] Next, a third embodiment of the vehicle body lifting support device 20 will be described. In the third embodiment, only the differences from the first embodiment will be described, and the same reference numerals will be given to parts that are the same as those in the first embodiment, and description thereof will be omitted. The vehicle body lifting support device 20 of the third embodiment does not have the sixth oil passage 53 and the seventh oil passage 54 in the hydraulic circuit shown in FIG. 2 and is the same as the conventional hydraulic circuit shown in FIG. Is. Further, as shown in FIG. 7, a plate support member 83 extending vertically is provided outside the left and right end portions of the through hole 41 on the back side of the panel 43 provided on the front surface of the operation device 30, and the pair of plate support members 83 are provided. A plate 85 is vertically movably mounted between the plate support members 83.

8 and 9, the plate 85 extends in the left-right direction (vertical direction in FIG. 8) and has a rectangular shape, and a rectangular insertion hole 87 extending in the left-right direction is formed in the central portion. Has been formed. As shown in FIG. 9A, the insertion hole 87
The width X1 in the left-right direction of the five operation levers 31 arranged side by side
The distance X0 between the pair of operation levers 31a, 34a arranged on the outermost side among a, 32a, 39a, 33a, 34a.
Have larger dimensions than. Further, the vertical width Y0 of the insertion hole 87 is determined by the operation levers 31a, 32a, 33.
When the a and 34a are tilted back and forth from the neutral position, the widths of the tilted position and the neutral position are substantially the same. However, the vertical width Y1 in the central portion of the insertion hole 87 corresponding to the portion in which the drive lever 39a is disposed is such that the operation lever 39a has the insertion hole 87 regardless of the positions of the operation levers 31a, 32a, 33a, 34a. It has a width that does not come into contact with the end portion, for example, a width that is substantially the same as the movable width of the operation lever 39a. Further, the width X2 in the left-right direction at the central portion of the insertion hole 87 corresponding to the portion where the operation lever 39a is arranged is larger than the width in the left-right direction of the operation lever 39a.

In the operating device having the above-described structure, for example, the operating lever 39a shown in FIG. 9A and the operating levers 32a and 33a adjacent to the left and right of the operating lever 39a are in the neutral position, and the operating levers are provided at both left and right ends. When the operation levers 32a adjacent to the left side of the operation lever 39a are erroneously operated and tilted rearward when the operation levers 31a and 34a are tilted forward, as shown in FIG. 9B, The plate 85 moves to the rear side by the operation lever 32a.
At the same time, the upper end of the insertion hole 87 pushes the operation levers 31a and 34a provided at both left and right ends to the rear side, and these operation levers 31a and 34a move to the neutral position.
Therefore, the operation lever 31a that has already been tilted,
The other operating lever 32a in a direction different from the tilting direction of 34a.
Even if is operated, it is possible to prevent a situation in which operation levers having different tilt directions are mixed.

As a result, as shown in FIG. 10 of the above-mentioned prior art, the selector valve 34 is operated to the jack side and the entrance / exit switching valve 39 is operated to the extension side, and the jack cylinder 27 is extended to move the jack 26. When the selector cylinder 31 connected to the other selector valve 31 extends when the other selector valve 31 is operated to the extension side after the grounding is performed and the inlet / outlet switching valve 39 is operated to the neutral state, 9 will be added to explain the plate 8
If the operating device 30 provided with 5 is used, when another selector valve 31 that is operated later is operated to the extension side, the operating lever 34 of the selector valve 34 that has already been operated is operated.
a moves to the neutral position. For this reason, the second oil passage 48 and the first oil passage 47 are cut off from each other, so that the overhanging cylinder 24 connected to the other selector valve 31 that is operated later is connected.
Since hydraulic pressure does not act on the extension cylinder 24, the extension cylinder 24 does not extend, and the selector valve 3 that has already been operated does not move.
The jack cylinder 27 connected to 4 also does not contract.

As described above, the plate 85 is attached to the operating device 30.
It is economical because it is possible to prevent the cylinder from being driven contrary to the operator's will only by providing.

[0044]

As described above, according to the vehicle body lifting support device of the present invention, the jack is extended by providing the hydraulic pressure reducing means for reducing the hydraulic pressure in the second oil passage and the third oil passage. When the cylinder drive control valve is switched to the neutral state and the cylinder selection valve different from the initially operated cylinder selection valve is erroneously operated to the extension side when the cylinder drive control valve is switched to the neutral state, the hydraulic pressure lowering means is the second. Since the oil pressures of the oil passage and the third oil passage are reduced, the oil pressure does not act on the extension cylinder connected to the incorrectly operated cylinder selection valve, and the extension movement of the extension cylinder can be prevented.
It is possible to prevent the contraction movement of the jack cylinder of the jack in the grounded state.

Further, according to the vehicle body lifting support device of the present invention, the fifth oil passage is communicated with the rod connecting oil passage and the rod connecting oil passage that connect the rod chambers of the plurality of overhanging cylinders to each other.
It has a communication oil passage connected to the oil passage, and by providing a pilot check valve in the communication oil passage, the jack extends and moves to the grounded state, and when the cylinder drive control valve is switched to the neutral state. If a cylinder selection valve different from the first operated cylinder selection valve is erroneously operated to the overhang side, the oil flow from the fifth oil passage to the third oil passage is cut off, and the erroneously operated cylinder is operated. Even if the directional hydraulic pressure is applied to the extension cylinder connected to the selection valve, the fifth oil passage connected to the rod chamber of the extension cylinder is blocked, so the extension motion of the extension cylinder is restricted. can do. Further, since oil does not flow from the fifth oil passage to the third oil passage, it is possible to prevent the jack cylinder of the grounded jack from contracting.

According to the vehicle body lifting support device of the present invention, when the operating device tilts the selection lever from the neutral position to either the front or rear side, the other selection lever is moved to the other side. By restricting the tilting operation and providing the lever operation restricting means that enables the front and rear operation of the drive lever, it is possible to prevent the selection lever from being operated in a mixed state from the neutral position to either the front or rear side or the other side. Can be prevented. When the selection lever tilted to the front side and the selection lever tilted to the rear side coexist, the cylinder drive control valve does not control the oil supply / discharge, but the overhang cylinder. Even if the vehicle body lifting support device is capable of extending, the extension motion of the extension cylinder can be prevented only by attaching the lever operation restricting means to the vehicle body lifting support device, which is economical.

[Brief description of drawings]

FIG. 1 is a perspective view of an aerial work vehicle equipped with a vehicle body lifting support device according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of the vehicle body lifting support device according to the first embodiment of the present invention.

FIG. 3 is a partial hydraulic circuit diagram of the vehicle body lifting support device according to the first embodiment of the present invention.

FIG. 4 shows an operating device according to the first embodiment of the present invention, FIG. 4 (a) is a plan view of the operating device, and FIG. 4 (b) is a side view of the operating device.

FIG. 5 is a hydraulic circuit diagram of the vehicle body lifting support device according to the first embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram of a vehicle body lifting support device according to a second embodiment of the present invention.

7A and 7B show an operating device according to a third embodiment of the present invention, FIG. 7A is a plan view of the operating device, and FIG. 7B is a side view of the operating device.

FIG. 8 shows a plan view of a plate of an operating device according to a third embodiment of the present invention.

FIG. 9 is a view for explaining the operation of the operating device according to the third embodiment of the present invention.

FIG. 10 is a hydraulic circuit diagram of a vehicle body lifting support device in the related art.

[Explanation of symbols]

20 Car Body Lifting Support Device 21 Outrigger Device 23 Overhanging Beam 24 Overhanging Cylinder 26 Jack 27 Jack Cylinders 31, 32, 33, 34 Selector Valves (Cylinder Selection Valves) 31a, 32a, 33a, 34a Operation Lever (Selection Lever) 39a Operation lever (drive lever) 39 Inlet / outlet switching valve (cylinder drive control valve) 47 First circuit 48 Second circuit 49 Third circuit 50 Fourth circuit 51 Fifth circuit 51a Rod connecting oil passage 51b Communication oil passage 52 Sixth oil passage (Hydraulic pressure lowering means) 53 Seventh oil passage (hydraulic pressure lowering means) 54 Eighth oil passage 56 First throttle 57 Second throttle 58 Third throttle 60, 77 Pilot line 61 Pilot check valve (pressure lowering means) 65, 66, 79 Pilot check valve 67 Double pilot check valve 71 Electromagnetic valve Oil passage opening and closing valve) 73 controller (valve operation control means) 75 a neutral position sensor (neutral detecting means) 85 plate (lever operation restricting means) P hydraulic pump (hydraulic source)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoji Oikawa             1015 1152 Yamashita, Ryoke, Ageo City, Saitama Prefecture               Aichi Corporation Ageo Kogyo             Inside the hall F-term (reference) 3D026 EA06 EA26 EA48 EA54 EA74                 3F333 AA08 CA15 DA10 DB10 FA10                       FB02 FH08                 3H089 AA01 AA60 AA73 AA74 BB28                       BB30 CC12 DA02 DB13 DB34                       DB45 DB47 DB48 DB49 DB54                       FF05 GG02 JJ07                 3J070 AA03 BA02 BA41 BA51 CD21

Claims (5)

[Claims] 1. A projecting beam that can project freely in the vehicle width direction,
A projecting cylinder for projecting and moving the projecting beam in the vehicle width direction; a jack attached to a tip end of the projecting beam and capable of expanding and contracting vertically; and a jack cylinder for expanding and contracting the jack. A plurality of outrigger devices arranged on the side of the vehicle body, and a plurality of outrigger devices provided corresponding to the outrigger devices, respectively, for causing the overhang cylinder and the jack cylinder to selectively supply oil. A cylinder selection valve, a cylinder drive control valve for controlling the supply and discharge of oil from a hydraulic pressure supply source to the cylinder selection valve, a first oil passage connecting the cylinder drive control valve and the cylinder selection valve, and A second oil passage connecting a cylinder selection valve and a bottom chamber of the jack cylinder, a rod chamber of the jack cylinder, and the cylinder drive control valve. And a fourth oil passage connecting the cylinder selection valve and the bottom chamber of the extension cylinder, and a fifth oil passage connecting the rod chamber of the extension cylinder and the third oil passage. And a pilot check valve disposed corresponding to each of the second oil passage and the third oil passage, the pilot check valve allowing the flow of oil to the jack cylinder side. A pilot check valve that restricts the flow of oil to the cylinder selection valve side and the cylinder drive control valve side and that is arranged upstream of the oil flowing in the second oil passage and the third oil passage. When the pilot pressure in the oil passage on the upstream side is received, the pilot check valve arranged on the downstream side is opened to allow the oil flow to the cylinder selection valve side and the cylinder drive control valve side. In the vehicle body lifting support device having a double pilot check valve configured as described above, the cylinder drive control valve is configured to cut off the oil supply to the cylinder selection valve in a neutral state, A vehicle body lifting support device having pressure reducing means for reducing the hydraulic pressure in the second oil passage and the third oil passage when the control valve is switched to the neutral state. 2. The pressure reducing means connects between the first oil passage and the tank, connects between a sixth oil passage having a first throttle, and connects between the third oil passage and the tank, A pilot line is connected to a seventh oil passage having a second throttle, and an eighth oil passage which is arranged in the sixth oil passage and the seventh oil passage and which connects the oil supply source and the cylinder drive control valve. A third throttle is provided in the pilot line, the pilot pressure of the oil flowing in the eighth oil passage is received through the pilot line, the regulation of the oil flow to the tank side is released, and the second oil passage is released. And a pilot check valve for causing the oil in the third oil passage to flow into the tank through the sixth oil passage and the seventh oil passage. Upper support device. 3. The neutralization detection means for detecting whether the cylinder drive valve is in a neutral state, the sixth oil passage connecting the first oil passage and the tank, A third oil passage, a seventh oil passage connecting to the tank, an oil passage opening / closing valve arranged in the sixth oil passage and the seventh oil passage to communicate or block these oil passages, and the neutral Valve operation control means for operating the oil passage opening / closing valve to communicate the sixth oil passage and the seventh oil passage when the detection means detects that the cylinder drive valve is in a neutral state. The vehicle body lifting support device according to claim 1, wherein: 4. An overhanging beam which can overhang in the vehicle width direction,
A projecting cylinder for projecting and moving the projecting beam in the vehicle width direction; a jack attached to a tip end of the projecting beam and capable of expanding and contracting vertically; and a jack cylinder for expanding and contracting the jack. A plurality of outrigger devices provided on the left and right of the vehicle body, provided corresponding to the outrigger devices, respectively, and a plurality of cylinder selection valves for selectively supplying oil to the overhang cylinder and the jack cylinder, A cylinder drive control valve that controls the supply and discharge of oil from a hydraulic pressure supply source to the cylinder selection valve; a first oil passage connecting the cylinder drive control valve and the cylinder selection valve; the cylinder selection valve; A second oil passage connecting the bottom chamber of the jack cylinder, and a second oil passage connecting the rod chamber of the jack cylinder and the cylinder drive control valve. An oil passage, a fourth oil passage connecting the cylinder selection valve and the bottom chamber of the extension cylinder, and a fifth oil passage connecting the rod chamber of the extension cylinder and the third oil passage, A pilot check valve is provided corresponding to each of the second oil passage and the third oil passage, and the pilot check valve allows oil to flow toward the jack cylinder side, and the cylinder check valve side and the cylinder The flow of oil to the drive control valve side is regulated and the second
When the pilot pressure of the oil passage on the upstream side of the pilot check valve arranged on the upstream side of the oil flowing through the oil passage and the third oil passage is received, the pilot check valve arranged on the downstream side is opened and the pilot check valve is opened. In a vehicle body lifting support device having a double pilot check valve configured to allow oil flow to the cylinder selection valve side and the cylinder drive control valve side, the cylinder drive control valve is in a neutral state. The fifth oil passage is configured to cut off the supply of oil to the cylinder selection valve, and the fifth oil passage communicates with a rod connecting oil passage that connects rod chambers of the plurality of overhanging cylinders and the rod connecting oil passage. And a communication oil passage connected to the third oil passage, which is arranged in the communication oil passage and is connected to the eighth oil passage connecting the oil supply source and the cylinder drive control valve. The oil line to the extension cylinder side to restrict the flow of oil to the cylinder drive valve side and to connect the eighth oil passage when the cylinder drive valve is in a neutral state. A vehicle body lifting support device having a pilot check valve for restricting the flow of oil to the cylinder drive valve side even when receiving pilot pressure of flowing oil via the pilot line. 5. A bulging beam projecting and moving in a vehicle width direction, and a jack attached to a tip end portion of the bulging beam and capable of expanding and contracting up and down are provided on a side portion of a vehicle body. A plurality of outrigger devices provided, a cylinder selection valve provided corresponding to each of the outriggers, for selectively supplying oil to the overhang cylinder and the jack cylinder, and oil from a hydraulic pressure supply source. A cylinder drive control valve that controls the supply and discharge of the cylinder selection valve, the cylinder selection valve has a selection lever that can be tilted forward and backward from a neutral position, and the selection lever can be tilted forward and backward from the neutral position. Then, oil can be supplied to the overhanging beam or the jack according to the operation, and the cylinder drive control valve can be tilted back and forth from the neutral position. A vehicle body lifting support device that has a drive lever and supplies oil to the overhanging beam or the jack selected by the cylinder selection valve when the drive lever is tilted back and forth from a neutral position. When the tilting operation is performed from the neutral position to either the front or rear side, the lever operation restricting means that restricts the tilting operation of the other selection lever to the other front or rear side and enables the front and rear operation of the drive lever. A vehicle body lifting support device having: