JPH10157992A - Vehicle for high lift work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lock a bucket from a car boy longitudinal direction and surely prevent action of a load by inertia force to an articulated arm at rapid acceleration/ deceleration time. SOLUTION: On an under carriage 3 of a high lift work vehicle 1, a boom 5 is provided capable of derricking. In a tip end of the boom, a bucket 7 is provided through an articulated arm 8. On the under carriage, a mounting stand 14 mounting a work bench in a storage position is vertically provided. In the mounting stand, a restriction means 21 restricting movement in a car body longitudinal direction of the bucket is provided. The restriction means is provided with a pair of front/rear holding implements 24, 25 holding from a car body longitudinal direction a fixed plate 23 protruded from a bucket lower part and a pair of hydraulic cylinders connected to each holding implement to extend/contract in the car body longitudinal direction by supply/discharge of pressure oil. Each holding implement is contacted and separated relating the fixed plate associated with extending/contracting action of each hydraulic cylinder. A switching valve switching supply/discharge of pressure oil relating to each hydraulic cylinder is made to perform switching operation associated with protruding/sinking action of an inner cylinder 17b of a rear side jack 17R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aerial work vehicle in which a boom is raised and lowered on a chassis to move the platform from a low position to a high position. Pertaining to measures to restrict movement in the direction.

[0002]

2. Description of the Related Art For example, as disclosed in Japanese Utility Model Publication No. 5-47187, a boom is provided on a chassis of an aerial work vehicle so as to be able to rise and fall and extend and extend, and a work table is hinged to a tip of the boom. Is provided via A mounting stand is erected on the chassis. At the time of work, an operator gets on the work table, raises and lowers the boom to move the work table between a high position and a low position, and places the work table on the neck with the hinge as a rotation center. I'm trying to shake it. On the other hand, when traveling, the work table is mounted on a mounting stand.

[0003] A pair of left and right projections are provided at the upper end of the mounting stand, and when the vehicle is running or not working, the movement of the work table in the left-right direction of the vehicle body by the respective projections is caused on the mounting stand. The work table is restrained so as not to be displaced laterally from above the mounting stand during traveling or the like.

[0004]

By the way, if the vehicle is suddenly accelerated or decelerated while traveling with the work table stored, an inertial force acts on the work table and the work table tends to move in the longitudinal direction of the vehicle body. I do. In this case, in the above-described conventional apparatus, the work table is trying to move in the vehicle body front-rear direction since the movement in the vehicle body front-rear direction is not restricted. Therefore, the load due to the inertial force on the work table acts on the hinge, which is a movable part, and an excessive load acts on the hinge. In addition, when the weight of the work table is increased by, for example, keeping the work implement mounted on the work table, the load acting on the hinge also increases, and the hinge is damaged due to the inertial force on the work table. There is fear.

[0005] Further, in order to make effective use of the space on the undercarriage, the workbench may be stored in a state of being bent at a predetermined angle around the hinge with respect to the boom in plan view with respect to the boom. In this case, there is also a problem that when an inertial force acts on the work table, a considerably excessive load acts on the hinge.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to make it possible to restrain a work table from the front-rear direction of a vehicle body so that a load due to an inertial force applied to a hinge during sudden acceleration / deceleration can be obtained. The function of the present invention is surely prevented.

[0007]

Means for Solving the Problems In order to achieve the above object, a solution according to the first aspect of the present invention is provided on a chassis so as to be able to undulate and expand and contract, and a worktable is provided at a tip end via a hinge. Boom, and a mounting stand erected on the undercarriage, at the time of work, an operator gets on the workbench, raises and lowers the boom, and moves the worktable to a high position and a low position. , The work table is swung about the hinge as a center of rotation, and the work table is placed on a mounting stand during traveling. Further, a restraint means for restraining the work table in the longitudinal direction of the vehicle body is provided on the mounting stand.

[0008] The solution taken by the invention of claim 2 is as follows.
The restraining means according to the first aspect of the present invention is specified. Specifically, the restraining means includes a holding means for holding a fixed plate protruding below the lower portion of the worktable from the front and rear direction of the vehicle body, and a holding means for holding the fixing means to the fixed plate in the front and rear direction of the vehicle body. And operating means for operating.

According to the first and second aspects of the present invention, the work table tends to move in the front-rear direction of the vehicle body due to inertial force due to sudden acceleration / deceleration during traveling with the work table stored. For example, the worktable is restrained from moving in the vehicle longitudinal direction by restraining means for restraining the worktable by, for example, gripping the fixing plate projecting below the worktable from the vehicle longitudinal direction by operating means. Inertia force does not act on the table, and it is possible to prevent an unreasonable load or a large load that may be damaged from acting on a movable part such as a hinge.

[0010] The solution taken by the invention of claim 3 is as follows.
According to a second aspect of the present invention, the structure of the holding means and the operating means is specified. Specifically, the clamping means
A pair of clamps are provided to clamp a fixed plate protruding below the lower part of the worktable from both front and rear directions of the vehicle body. It has a pair of hydraulic cylinders that expand and contract. Then, each of the holding members is configured to be brought into contact with and separated from the fixed plate in the front-rear direction of the vehicle body in conjunction with the expansion and contraction operation of each hydraulic cylinder.

According to the third aspect of the present invention, the pair of clamps for clamping the fixed plate are moved relative to both the front and rear of the fixed plate in conjunction with the expansion and contraction operation of the hydraulic cylinder. When the workbench is retracted by the boom tilting operation, when the restraining means (clamping tool) is a fixed type, in order to avoid interference with the clamping tool, It is not necessary to store the workbench from directly above the mounting stand, and the workbench can be moved by moving the clamps in the direction away from the fixed plate. It is mounted (stored) on the mounting stand without any trouble.

The solution taken by the invention according to claim 4 is as follows:
In addition to the constituent features of the third aspect of the present invention, a switching valve for switching supply / discharge of hydraulic pressure to / from each hydraulic cylinder is interposed between each hydraulic cylinder and its hydraulic source. Further, between the switching valve and each of the hydraulic cylinders, a pair of holding members are brought into contact with the fixing plate from both sides in the front-rear direction of the vehicle body to supply and discharge the hydraulic pressure to and from the respective hydraulic cylinders while holding the fixing plate. Is provided with an on-off valve for shutting off.

According to the fourth aspect of the present invention, when the work table is restrained by holding the fixing plate by each holding tool, the supply and discharge of the hydraulic pressure to the hydraulic cylinder is shut off. The holding device is prevented from separating from the fixing plate due to the leakage of the hydraulic pressure. In addition, even if a compressive force is applied to the hydraulic cylinder via the fixing plate due to the inertial force acting on the work table at the time of sudden acceleration / deceleration, that is, a compressive force that causes each of the holding members to separate from the fixing plate, the hydraulic cylinder is not affected. Since the supply and discharge of the hydraulic pressure are shut off, it is possible to sufficiently withstand the compressive force applied to the hydraulic cylinder.

[0014] The solution means taken by the invention according to claim 5 is as follows.
In addition to the constituent features of the invention described in claim 4, a plurality of jacks are provided at the front, rear, left and right of the chassis, and each of the jacks includes an outer cylinder and an inner cylinder. Then, the switching valve is switched in conjunction with the retracting operation of the outer cylinder or the inner cylinder of each jack.

The solution taken by the invention according to claim 6 is as follows.
In addition to the constituent features of the invention described in claim 4 or claim 5,
A switching valve is mounted on one of the outer cylinder and the inner cylinder of the jack, and a cam for switching the switching valve is provided on the other.

According to the fifth and sixth aspects of the present invention, the switching valve moves each holding member to the fixing plate by a cam or the like in conjunction with the jack protruding operation at the time of working at a high place on the work table. While being switched to be separated from each other, the switching is performed so as to hold (contact) the holding tool with respect to the fixing plate in conjunction with the immersion operation of the jack when the work table is stored. For this reason, the work table is reliably restrained or released without forgetting the restraint by the restraining means at the storage position of the work table and the release of the restraint when performing high-altitude work.

According to a seventh aspect of the present invention, there is provided a method according to the sixth aspect of the present invention, wherein a location where the switching valve and the cam are installed is specified. Specifically, a switching valve and a cam are provided on a jack in which the outer cylinder or the inner cylinder is immersed first when the chassis descends.

According to the seventh aspect of the present invention, the jack which is immersed most quickly when the chassis descends, for example, the immersion operation is quickly performed so that the braking force of the wheels can be obtained promptly after performing high-altitude work on a sloped ground. The switching valve is quickly switched over the sliding contact surface of the cam due to the immersion operation of the jack on the braking wheel side that needs to be performed. Therefore, by utilizing the time difference between the jack and the jack which is immersed later, the time required for the switching valve to switch over the sliding contact surface of the cam and then to clamp the fixing plate by the clamping device is sufficiently obtained. It is not necessary to operate the switch for immersing the jack until the holding plate is clamped by the clamp, as in the case of a jack that has a switching valve and a cam that is immersed with a delay, and the switching valve is effective. Is operated.

[0019]

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

FIG. 1 shows an aerial work vehicle according to an embodiment of the present invention. The aerial work vehicle 1 has a pair of left and right body frames A extending rearward from a lower surface of a cabin 2 (only one of them is shown in the figure). A flat undercarriage 3 is provided on the upper side. The chassis 3 is formed in a rectangular shape that is long in the longitudinal direction of the vehicle body.

A turning post 4 is provided at the rear of the chassis 3 so as to be turnable in a horizontal plane. The turning post 4 is
A pair of left and right turning columns 4a (only one is shown in the figure) is provided. A boom 5 (a base end boom 5a described later) having a substantially rectangular cross section is supported via a shaft 6 between the upper ends of the turning columns 4a (upper ends of the turning posts 4) so as to be rotatable in the vertical direction. I have. The boom 5 is supported by a base boom 5a pivotally supported by the turning post 4, an intermediate boom 5b inserted and supported on the base boom 5a so as to be able to protrude and retract, and inserted and supported so as to be protrudable and retractable on the intermediate boom 5b. The end boom 5c forms a multi-stage boom. At the tip of the tip boom 5c,
One end of a joint arm 8 as a hinge is rotatably supported around a first vertical axis m1. At the other end of the articulated arm 8, a bucket 7 as a work table on which an operator gets in and works is rotatably supported around a second vertical axis m2. The bucket 7 is supported by two vertical axes m1 and m2 at both ends of the joint arm 8 so that the bucket 7 can swing right and left around one end or the other end or both ends of the joint arm 8 as a fulcrum.

A telescopic cylinder (not shown) is provided between the base boom 5a and the distal boom 5c, and the telescopic cylinder causes the boom 5 to expand and contract. Also, the base end boom 5 of the boom 5
A lifting cylinder 11 is provided between a and the turning post 4, and the boom 5 is raised and lowered as the lifting cylinder 11 expands and contracts. In addition, turning post 4
A horizontal cylinder (not shown) between the base boom 5a and the distal boom 5c and the joint arm 8 respectively.
These two cylinders allow the joint arm 8 to rotate around the axis 9 at the tip of the tip boom 5c, regardless of the state of the ups and downs of the boom 5, and the bucket 7 to be held in a horizontal position. .

The swivel post 4 has a swivel base 1 at its base.
The turntable 12 is rotatably supported on the chassis 3. The turning post 4 and the boom 5 are turned by a turning motor (not shown). The turning post 4 and the boom 5 are capable of turning about 180 ° around both the left and right sides with reference to a state in which the joint arm 8 is positioned on an extension of the boom 5.

At the front end of the undercarriage 3, there is provided a boom stand 13 on which the vicinity of the distal end of the boom 5 (base end boom 5a) is to be placed at its lowered position. In addition, the undercarriage 3
A mounting stand 14 for mounting the bucket 7 at the storage position is provided upright near the center of the box. The boom stand 13 and the mounting stand 14 face left and right across the vehicle body center line (not shown), and the boom stand 13 is tilted at a predetermined angle with respect to the boom 5 in a plan view. 5 and bucket 7 each on stand 1
It is designed to be placed on and stored on 3 and 14. At the upper ends of the boom stand 13 and the mounting stand 14, plate-shaped brackets 15, 16 extending in the left-right direction of the vehicle body are provided, and the boom 5 and the bucket 7 are mounted via the brackets 15, 16. It has become. The dimensions of the brackets 15 and 16 in the left-right direction substantially match the lengths of the boom 5 and the bucket 7 in the left-right direction of the vehicle, and projecting pieces 15a and 16a projecting upward from both left and right ends thereof (only one in the figure). Show)
This restricts the movement of the boom 5 and the bucket 7 in the left-right direction of the vehicle body.

At the four corners of the chassis 3, a pair of left and right front and rear jacks 17F, 17R (only one is shown in the figure) are provided. Each jack 17
F and 17R each include an outer cylinder 17a and an inner cylinder 17b slidably supported on the inner peripheral surface of the outer cylinder 17a. The outer cylinder 17a is fixedly provided at each of four corners of the chassis 3 in front, rear, left and right. An extensible hydraulic cylinder (not shown) is linked to the outer cylinder 17a and the inner cylinder 17b,
When the aerial work vehicle 1 is operated, the aerial work vehicle 1 (the undercarriage 3) is moved forward by projecting the inner cylinder 17b of each of the jacks 17F and 17R below the lower end of the outer cylinder 17a with the extension of the hydraulic cylinder. The WF and the rear wheel WR are supported above in place of the rear wheel WR. On the other hand, when the boom 5 and the bucket 7 are stored, the inner cylinder 17b of each jack 17 is immersed in the outer cylinder 17a with the contraction of the hydraulic cylinder, so that the aerial work vehicle 1 (the undercarriage 3) can travel. I am trying to put it in a state. A jack base 17 having a shape larger than the outer cylinder 17a in a plan view is provided at a lower end of the inner cylinder 17b.
c is attached.

The rear wheel WR is a braking wheel for braking when the vehicle is parked or stopped. Then, each of the jacks 17F, 17
R varies the timing of the front and rear movements so that braking by the rear wheel WR (braking wheel) can be effectively obtained in consideration of a case of performing a high place work on a sloping ground.
Specifically, when the jack is projected, the front jack 17F is projected first to obtain the braking of the rear wheel WR, and then the rear jack 17R is projected. On the other hand, when the jack is immersed, the rear jack 17R is immersed first to obtain the braking of the rear wheel WR, and then the front jack 17F is immersed.

As shown in FIGS. 2 and 3,
The placing stand 14 is provided with a restraining means 21 for restraining the movement of the bucket 7 in the vehicle longitudinal direction. The restraining means 21 includes a holding means 20 and an operating means 22.
And The holding means 20 is provided with a pair of front and rear holding tools 24 and 25, and is configured to hold a fixing plate 23 protruding substantially at the center of the lower surface of the bucket 7 from the front and rear direction of the vehicle body. The fixing plate 23 is formed in a substantially T-shape when viewed from the side, and the front and rear holding surfaces of a holding portion 23a extending downward are directed in the vehicle longitudinal direction.

The pair of holding members 24 and 25 are relatively moved both before and after the holding portion 23a (fixing plate 23). The pair of holding members 24, 25 have rod members 24a, 25a extending on the same horizontal axis extending in the vehicle longitudinal direction. At the tips of the rod members 24a and 25a facing each other, pads 26 whose diameters increase toward the tip (toward the holding portion 23a) are attached, respectively, and the tips of the rod members 24a and 25a are inserted through the pads 26. Contact the front and rear holding surfaces of the holding portion 23a almost simultaneously from the front-rear direction of the vehicle body, and
Is sandwiched from the front and back. The rod members 24a and 25a are slidably inserted and supported at their base end sides by a guide tube 27, respectively, so that the rod members 24a and 25a can move forward and backward in the vehicle longitudinal direction. Below the bracket 16 of the mounting stand 14, an angle member 28 extending in the vehicle front-rear direction is attached by welding, and the guide tubes 27 are attached to both front and rear ends of the angle member 28, respectively.

On the other hand, the operating means 22 is provided at both front and rear ends of the angle member 28. This operating means 22
Is provided with a pair of hydraulic cylinders 31 and 32, and each of the cylinder tubes 31a and 32a is
6 is installed in parallel. Each of the above hydraulic cylinders 3
The cylinder rods 31b and 32b are arranged so that the cylinder rods 31b and 32b expand and contract in the vehicle longitudinal direction by supplying and discharging hydraulic pressure.
The distal ends of the rod members 24a and 25a and the distal ends of the cylinder rods 31b and 32b are individually connected by a pair of front and rear brackets 33, respectively. 2
4a and 25a move forward and backward, and their tips (pads 26) come into contact with and separate from the holding surface of the holding portion 23a. As a result, even when the bucket 7 moves in the front-rear direction due to inertial force due to sudden acceleration / deceleration or the like when traveling with the bucket 7 stored, the bucket 7 is moved forward and backward by the holding portion 23a (fixed plate 23) on the lower surface thereof. Holders 24, 25 (rod members 24a,
25a) is abutted and clamped, whereby the movement in the vehicle longitudinal direction is restrained, no inertial force acts on the bucket 7, and an excessive load or a large load is applied to the movable part such as the joint arm 8. The operation can be reliably prevented.

Next, the configuration of a hydraulic circuit for supplying and discharging hydraulic pressure to and from the hydraulic cylinders 31 and 32 will be described with reference to FIG.

In FIG. 4, reference numeral 41 denotes an oil tank. One end of a first oil passage 43 is connected to the oil tank 41, and an oil pump 42 as a hydraulic pressure source is provided in the middle of the first oil passage 43. Is interposed. The first oil passage 43
Is connected to a two-position switching valve 44 that switches between a first position (left position in the figure) and a second position (right position in the figure). The first oil passage 43 is connected to the switching valve 4.
4 is connected to one end of the second oil passage 45 when switched to the first position, while the third oil passage 4 is connected when switched to the second position.
6 is connected to one end.

The other end of the second oil passage 45 is connected to the head side chambers 31H and 32H of the hydraulic cylinders 31 and 32 via branch pipes 45a and 45a, respectively. On the other hand, the other end of the third oil passage 46 is connected to each of the hydraulic cylinders 3.
The first and second rod-side chambers 31R, 32R are connected via branch pipes 46a, 46a, respectively. The second oil passage 45 is provided with a flow regulating valve 47, a pilot operated check valve 48, and an on-off valve 49 in this order from one end thereof.

The flow regulating valve 47 is provided with a check valve 47a therein so that the pressure oil can flow regardless of the switching of the switching valve 44. The pilot operated check valve 48 is connected to the rod side chamber 31 of each of the hydraulic cylinders 31 and 32.
When the oil pressure of R, 32R exceeds the set pressure, the head side chamber 3
The pressure oil of 1H and 32H is released, and the rod side chambers 31R and 32 are released.
The R oil pressure is reduced. On-off valve 49
Are manually opened and closed, and each of the clamps 24, 25
For example, when the (rod members 24a, 25a) are brought into contact with the front and rear clamping surfaces of the clamping portion 23a and the clamping portion 23a is clamped from front and rear, the second oil passage 45 is shut off and each hydraulic cylinder 3 is closed.
The oil pressure in the head side chambers 31H and 32H of the first and second heads 32 is prevented from being released. As a result, the front and rear clamps 24, 2
5, when the bucket 7 is retracted by holding the holding portion 23a, the holding members 24 and 25 are caused to leak by the hydraulic pressure from the switching valve 44, the flow regulating valve 47, the pilot operated check valve 48 and the like. Is prevented from separating from the clamping surface of the helmet. In addition, even if a compressive force acts on each of the hydraulic cylinders 31 and 32 via the holding portion 23a due to the inertial force acting on the bucket 7 at the time of sudden acceleration / deceleration or the like, the supply and discharge of the hydraulic pressure to and from the hydraulic cylinders 31 and 32 are performed. Is blocked, it is possible to sufficiently resist the compressive force applied to each of the hydraulic cylinders 31 and 32, so that the bucket 7 can be effectively restrained from the vehicle longitudinal direction.

Then, as shown in FIG.
4 is a front jack 17F when the jack is immersed as described above.
It is provided on the rear jack 17R (right side or left side) that is immersed earlier. The switching valve 44 is attached to the outer cylinder 17a of the rear jack 17R so that the spool 44a is oriented horizontally. The tip of the spool 44a projects outward by the urging force of the spring 44b, and the switching valve 44 is moved to the second position. It switches to the position. A roller 51 is attached to the tip of the spool 44a. A cam 5 is provided on the jack base 17c (inner cylinder 17b side) of the rear jack 17R corresponding to the roller 51.
2 are erected. A cam surface 52a is formed on the upper portion of the cam 52 so that the roller 51 slides into and out of the spool 44a. The cam surface 52a switches the switching valve 44 to the first position by retracting the spool 44a against the urging force of the spring 44b when the rear jack 17R enters, while the spring 44b is attached when the rear jack 17R projects. The switching valve 44 is switched to the second position by projecting the spool 44a by the force. That is, the switching valve 44 switches between the first position and the second position in conjunction with the retracting operation of the rear jack 17R. In this case, the spool 44a is retracted into the cam 52 when the rear jack 17R is retracted (the switching valve 44 is set to the first position).
The vertical surface 52b held in the state of being switched to the
It is formed continuously below 2a.

Here, the movement of the restraining means 21 at the storage position and the work position of the bucket 7 will be described. In this case, it is assumed that the bucket 7 is positioned at the high work position by the standing of the boom 5.

First, after finishing the work at the high work position, the up-and-down cylinder 11 is contracted so that the boom 5 is lowered. With the fall of the boom 5, the bucket 7 is lowered to position the bucket 7 at a low place, and the worker descends from the bucket 7. Thereafter, the boom 5 is slightly raised.
At this time, by rotating the bucket 7 around the first and second vertical axes m1 and m2 of the joint arm 8, the joint arm 8 is inclined with respect to the boom 5 by a predetermined angle in plan view.

Then, in this state, the boom 5 is lowered and the bucket 7 is also lowered accordingly, so that the boom 5 is placed on the boom stand 13 and the bucket 7 is placed on the mounting stand 14.
It is stored (placed) on each. At this time, jack 1
7F and 17R are in a protruding state, and as shown by the phantom line (two-dot chain line) in FIG. 5, the spool 44a of the switching valve 44 at the lower end of the outer cylinder 17a projects by the urging force of the spring 44b, and the switching valve 44 is in the fourth position. It has been switched to two positions. Therefore, the pressure oil from the oil pump 42 is supplied to each of the hydraulic cylinders 31 and 45 via the third oil passage 46 and the branch pipes 45a and 45a.
The hydraulic cylinders 31 and 32 are supplied to the rod-side chambers 31R and 32R, respectively, and are contracted. Thereby, each of the holding members 24, 25 (rod members 24a, 25a)
As shown by the solid line in FIG. 2 and the phantom line (two-dot chain line) in FIG. 3, the pads 26 at the tip end respectively correspond to the clamping surfaces before and after the clamping portion 23a as the hydraulic cylinders 31 and 32 contract. The bucket 7 does not have to be stored from directly above the mounting stand 14 in order to avoid interference with the clamps 24 and 25. It can be stored on the bracket 16 of the mounting stand 14 without difficulty.

Thereafter, each of the jacks 17F and 17R is immersed in a running state. The immersion operation of the jacks 17F and 17R is performed first from the rear jack 17R. At this time, when the rear jack 17R is immersed, the switching valve 44
As shown by the solid line in FIG. 5, the roller 51 at the tip of the spool 44a is connected to the cam surface 5 of the cam 52 of the jack base 17c.
Sliding contact is made from 2a to the vertical surface 52b, the spool 44a is immersed against the urging force of the spring 44b, and the switching valve 44 is switched to the first position. Therefore, the pressure oil from the oil pump 42 is supplied to the first oil passage 43, the second oil passage 45, and the branch pipe 4.
The hydraulic cylinders 31 and 32 are supplied to the head side chambers 31H and 32H of the hydraulic cylinders 31 and 32 via 5a and 45a, respectively, and the hydraulic cylinders 31 and 32 extend. Each of the hydraulic cylinders 31,
With the extension of 32, the front ends (pads 26) of the front and rear holding members 24, 25 (rod members 24a, 25a) are indicated by imaginary lines (two-dot chain line) in FIG. 2 and solid lines in FIG. Relative movement from both the front and rear sides of the holding portion 23a makes contact with the holding surfaces before and after the holding portion 23a, and the holding portion 24a is held by the holding members 24 and 25 in conjunction with the immersion operation of the jack 17.

Thus, the constraint by the constraint means 21 at the storage position of the bucket 7 is not forgotten.
Can be reliably restrained. In addition, the roller 51 at the leading end of the spool 44a of the switching valve 44 slides over the cam surface 52a of the cam 52 and slides on the vertical surface 52b by the retracting operation of the rear jack 17R, which is the earliest retracted when the chassis 3 descends. It is switched to one position. For this reason, the rear jack 1
Utilizing the time difference from the front jack which is immersed later than 7R, the time required to clamp the clamping portion 23a with the clamping members 24 and 25 after the switching valve 44 is switched to the first position, that is, the hydraulic cylinder The time required for the extension operations of the switches 31 and 32 is sufficiently ensured, and the switching valve 44 can be effectively operated.

On the other hand, when the work is performed by the bucket 7 from this storage position, the jacks 17F and 17R are protruded to be in the work state. The projecting operation of the jacks 17F and 17R is performed in the order of the front jack 17F and the rear jack 17R. At this time, the roller 51 at the leading end of the spool 44a of the switching valve 44
The cam 52 of the jack base 17c slides from the vertical surface 52b of the cam 52 on the cam surface 52a, and the spool 44a is protruded by the urging force of the spring 44b to switch the switching valve 44 to the second position, thereby contracting each of the hydraulic cylinders 31, 32. As the hydraulic cylinders 31 and 32 contract, the pads 26 at the front and rear of the front and rear holding members 24 and 25 move relatively to both the front and rear of the holding portion 23a and separate from the front and rear holding surfaces of the holding portions 23a. , 25 are released in conjunction with the projecting operation of the jack 17. In this case, each of the holding members 24 and 25 has a pad 26 at the tip of the holding member 24, 25.
Since the restraint by the restraint means 21 is released when the gripper 21 slightly separates from the front and rear clamping surfaces 3a, the switching of the switching valve 44 to the second position is delayed by the rear jack 17R projecting behind the projecting operation of the front jack 17F. There is no problem even if it is linked with the protruding operation of.

Thus, when the bucket 7 is moved from the storage position to the work position, the restraint release by the restraint means 21 is not forgotten, and the restraint means 21 can be used smoothly.

It should be noted that the present invention is not limited to the above embodiment, but includes various other modifications. For example, in the above-described embodiment, the switching of the switching valve 44 is performed in conjunction with the retracting operation of the rear jack 17R. However, the switching valve may be switched in conjunction with the retracting operation of the front jack.

Further, the switching valve may be of an electromagnetic type that is switched by a signal output when the jack is moved in and out.

Further, a non-interlocking switching valve that does not interlock with the jacking-out operation may be used.

Further, in the above embodiment, the switching valve 44 is provided on the outer cylinder 17a of the rear jack 17R and the cam 52 is provided on the jack base 17c (the inner cylinder 17b side), but the jack of the front or rear jack is provided. Needless to say, the switching valve may be received on the base (inner cylinder) and the cam may be received on the outer cylinder.

[0046]

As described above, according to the aerial work vehicle according to the first and second aspects of the present invention, the holding tool is held in the front-rear direction of the vehicle body with respect to the fixed plate protruding from the lower portion of the worktable. The work table placed on the mounting stand is restrained from moving in the front-rear direction of the vehicle body, so the inertial force due to sudden acceleration / deceleration to the work table is supported by the restraining means, and the action of the load on the hinge is reduced. It can be reliably prevented.

According to the third aspect of the present invention, a pair of clamps for clamping the fixing plate from the front and rear direction of the vehicle body are provided from both the front and rear of the fixing plate in conjunction with the expansion and contraction of the pair of hydraulic cylinders. The work table can be easily stored on the mounting stand by moving the clamps in the direction away from the fixing plate, because the booms fall and fall.

According to the fourth aspect of the present invention, since the supply and discharge of hydraulic pressure to the hydraulic cylinder is shut off when the fixing plate is clamped by the clamp, leakage of hydraulic pressure from the switching valve or the like is prevented. It is possible to reliably prevent the holding member from being separated from the fixed plate by a compressive force applied to the hydraulic cylinder by an inertial force acting on the work table at the time of sudden acceleration / deceleration or the like.

According to the aerial work vehicle according to the fifth and sixth aspects of the present invention, the switching valve is switched in conjunction with the operation of the jack, so that the worktable can be reliably restrained or released.

Further, according to the aerial work vehicle of the present invention, since the switching valve and the cam are provided on the jack that immerses the earliest when the chassis descends, the time difference between the jack and the jack that immerses later can be reduced. Utilizing this, it is possible to secure sufficient time for the switching valve to be switched over the sliding surface of the cam and then to hold the fixed plate by the holding member, and the switching valve can be operated effectively.

[Brief description of the drawings]

FIG. 1 is a side view of an aerial work vehicle according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of the restraining means of FIG.

FIG. 3 is a plan view of the restraining means.

FIG. 4 is a hydraulic circuit diagram of a hydraulic cylinder.

FIG. 5 is a side view of the rear jack showing the vicinity of the switching valve.

[Explanation of symbols]

 Reference Signs List 1 aerial work vehicle 3 chassis 5 boom 7 bucket (work table) 8 articulated arm (hinge) 14 mounting stand 17F, 17R front and rear jacks (jacks) 17a outer cylinder 17b inner cylinder 20 clamping means 21 restraining means 22 operation Means 23 Fixing plate 24, 25 Clamping tool 31, 32 Hydraulic cylinder 44 Switching valve 49 On-off valve 52 Cam m1, m2 Hinge shaft

Claims (7)

[Claims] 1. A boom provided on a chassis so as to be able to undulate and expand and contract, and a worktable provided at a tip end via a hinge; and a mounting stand erected on the chassis, and A person gets on the work table, raises and lowers the boom to move the work table between a high position and a low position, and swings the work table about the hinge as a rotation center. In an aerial work vehicle in which the work table is mounted on a mounting stand, the mounting stand is provided with restraining means for restraining the work table from moving in the vehicle longitudinal direction. High-altitude work vehicle. 2. The restraining means comprises: a holding means for holding a fixed plate protruding below a lower portion of the worktable from a front-rear direction of the vehicle body, and a front and rear body capable of holding the holding means to the fixed plate. 2. The aerial work vehicle according to claim 1, further comprising an operating means for operating in a direction. 3. The holding means includes a pair of holding tools for holding a fixed plate protruding below a lower portion of the worktable from both front and rear directions of the vehicle body, while the operating means includes the respective holding tools. And a pair of hydraulic cylinders which are connected to the main body and extend and contract in the longitudinal direction of the vehicle body by supplying and discharging hydraulic pressure. 3. The aerial work vehicle according to claim 2, wherein the aerial work vehicle is adapted to be driven. 4. A switching valve for switching supply / discharge of hydraulic pressure to / from each of the hydraulic cylinders is interposed between each of the hydraulic cylinders and a hydraulic source thereof, and between the switching valve and each of the hydraulic cylinders. An open / close valve is provided to shut off the supply and discharge of hydraulic pressure to each of the hydraulic cylinders in a state in which the pair of holding members are brought into contact with the fixing plate from both sides in the front-rear direction of the vehicle body to hold the fixing plate. The aerial work vehicle according to claim 3. 5. A plurality of jacks are provided on the front, rear, left and right of the chassis, each of the jacks has an outer cylinder and an inner cylinder, and the switching valve is an outer cylinder of each of the jacks or 5. The aerial work vehicle according to claim 4, wherein the switching is performed in conjunction with the movement of the inner cylinder. 6. The height according to claim 4, wherein the switching valve is attached to one of an outer cylinder and an inner cylinder of the jack, and a cam for switching the switching valve is provided to the other. Work vehicle. 7. The aerial work vehicle according to claim 6, wherein the switching valve and the cam are provided on a jack into which the outer cylinder or the inner cylinder is immersed first when the chassis is lowered.