JPH05286698A - High place working vehicle - Google Patents

Abstract

PURPOSE:To facilitate manufacture and maintenance of a high place working vehicle by accommodating a hydraulic circuit inside of an elevating mechanism, and obviating necessity for use of any hydraulic hose. CONSTITUTION:A high place working vehicle includes a body 1, elevating table 5, and elevating mechanism 4 which consists of at least a pair of hydraulically expanding/contracting mechanisms 11, 12 coupled rotatably in the center, wherein the mechanisms 11, 12 are composed of a pair of thin. hollow outer cases 13, 14, 15, 16 arranged parallel. Hydraulic cylinders 25, 26, 27, 28 are inserted slidably in these outer cases, and the tips of the cylinder rods of these cylinders are coupled with the outer cases 13, 14, 15, 16. The bases of the hydraulic cylinders 25, 26, 27, 28 are coupled with the the vehicle body 1 or elevating table 5.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is used for work in high places such as construction, assembly and painting of highways and high-rise buildings. The present invention relates to an aerial work vehicle used for loading and unloading materials from a high position, and particularly to an aerial work vehicle in which an elevating mechanism for elevating an elevating platform is formed with a simple structure similar to a hydraulic cylinder.

[0002]

2. Description of the Related Art In construction of highways, high-rise buildings and the like, aerial work vehicles for elevating a lifting platform up and down are often used for construction, assembly and painting work. It was also used extensively for the repair of traffic lights and lighting in high places. In this aerial work vehicle, it is possible to load a worker, materials and the like on an elevator and lift them, and to load and unload unnecessary materials from a work site at a high altitude.

In this conventional aerial work vehicle, a so-called (scissors type) expansion / contraction mechanism in the form of a pantograph in which a pair of arms are pivotally attached at the center to form one set and a plurality of sets of arms are vertically connected has been conventionally used. It was widely used.
In order to increase the maximum lifting capacity of the lifting platform in this mechanism, it was necessary to increase the length of the arms of each set or increase the number of arms to be connected. Therefore, in order to design an elevating mechanism capable of increasing the ascending height, it was necessary to use a large number of sets of pantographs. In such a mechanism, the height of the elevating mechanism when the pantograph is folded becomes high, and it becomes troublesome for a worker to get on and off the elevating table and to load and unload materials.

Various proposals have hitherto been made in order to solve these drawbacks, for example, British Patent 38206.
A structure such as the one disclosed in No. 31 is also proposed. In this proposed structure, the lower boom and the upper boom, which can move linearly with respect to the middle boom, are inserted into and removed from the middle boom, and the lower boom is pivotally supported by a pin on the vehicle body side at the lower end. The upper boom is assembled so that the upper end of the upper boom is pivotally supported on the platform with a pin to form an X shape. With this structure, the length of the boom itself becomes longer,
In the folded state, the height of the platform can be lowered and the platform can be lifted to a high position.

However, according to the present invention, since the mechanism for extending the lower boom and the upper boom from the middle boom is composed of the screw and the female screw meshing with the screw, the expansion and contraction moving speed of the lower boom and the upper boom relative to the middle boom is slow and the speed is high. It was not possible to respond to the platform. Also, since the lower boom and the upper boom are slid by the screw provided in the center of each middle boom, the total length of the lower boom and the upper boom can only be set to about half the length of the middle boom. It is a thing. Therefore, the lengths of the lower boom and the upper boom that extend and retract from the middle boom can only be set to about half the length of the middle boom, and there is a drawback that the platform cannot be lifted higher.

Also, by inserting another boom into the boom,
A structure has also been proposed in which the entire length of the telescopic boom itself is lengthened. For example, Japanese Patent Laid-Open Publication No. 1195, 1978
In Fig. 4 of the drawing of No. 56, the multi-stage boom with a small diameter and the upper boom are inserted into the thick middle boom, and the boom inserted inside is pulled out from the middle boom to increase the total length of the boom. Therefore, a structure for raising the platform high has been proposed.

However, in the present invention, there is no mechanism for synchronizing the amount of expansion and contraction between the lower boom and the upper boom that are pulled out from the middle boom, and they are individually moved, and the movement amount is determined by the bar link mechanism. It is a regulation. For this reason, the platform cannot be lifted in the vertical direction while being held horizontally, and cannot be lifted to the intended vertical upper position. Also, when the lower boom and the upper boom housed in the middle boom expand and contract, their movement amounts are regulated by the link mechanism formed by the bar, so it is impossible to completely synchronize the movement amounts of the two. there were. For this reason, the lower boom cannot be connected to the vehicle body and the upper boom to the platform by a pin or the like, and an error that cannot be synchronized has to be made by the rollers contacting the vehicle body and the platform. Due to this structure, the platform is subject to rolling by the link mechanism as it is, and has a structure that easily shakes, and easily swings due to wind or the like and is extremely unstable, which gives anxiety to workers.

Further, in FIG. 4 of the drawing, the X-shaped middle boom is rotated by a hydraulic cylinder attached to the outside, and the lower boom and the upper boom are pulled out by the rotation of the middle boom. The configuration is shown. The amount of pulling out of the upper boom and the lower boom is regulated by a link mechanism. Therefore, the operating force of the hydraulic cylinder acts linearly on the upper boom and the lower boom, and when the hydraulic cylinder is fully pulled out, the lengths of the upper boom and the lower boom are not pulled out as much as the entire length of the middle boom. Therefore, the maximum extension length of the entire boom to be extended cannot be made extremely long.

Next, as a structure for extending the entire length of the folded boom in the longitudinal direction, for example, Japanese Patent Application No.
A configuration such as 18492 of 2 years has also been proposed.

In this structure, the outrigger box is horizontally fixed to a part of the vehicle body, the inside of the outrigger box is divided by partition walls, and the outrigger beams are slidably inserted into the respective storage chambers. An operating cylinder is stored in one of the storage chambers. And both outrigger beams are connected by a rope. In this configuration, by activating the actuation cylinder, the outrigger beams can be retracted from the inside of the outrigger box, both outrigger beams can move in opposite directions, and each outrigger beam pulled out from within the outrigger box is about the length of the outrigger box. It can be extended to. This configuration is effective for pulling the outrigger beam out of the outrigger box for a long time.

However, this structure shows a structure for an outrigger for lifting the vehicle body and fixing it to the ground. Even if it is diverted to an aerial work vehicle as it is, the lift table can be moved up and down. It was something that could not be done. In addition, in the drawings described in this publication, both ends of both outrigger beams are not connected to any structure, and a configuration is shown in which the outrigger beams are simply expanded and contracted in the left and right horizontal directions. It's just that.

From such a point of view, a number of lifting mechanisms have been devised which are constructed so that a plurality of booms can be telescopically inserted into the inside of the arm and one arm can be extended in its length direction. For example, Japanese Patent Application No. 56,134,487, Japanese Patent Application No. 56,191,065 and the like can be mentioned.

In these newly proposed lifting mechanisms,
The three-tiered booms extend in the lengthwise direction, and X
When the middle booms whose central portions are connected to each other by a shaft in a letter shape rotate with respect to each other, the vehicle body and the lifting platform are configured to have an X shape when viewed from the side. In this structure, the lower boom and the upper boom extend the length of the middle boom, respectively, so that the lifting platform can be raised to a higher position. Further, since the respective tips of the lower boom and the upper boom are connected to the vehicle body or the lifting platform by pins, there is little rattling, and they can be firmly held against shaking.

In the lifting mechanism using the telescopic boom body which can be expanded and contracted in a plurality of stages, in order to extend and retract the lower boom and the upper boom from the middle boom, the hydraulic pressure interposed between the vehicle body and the center of the middle boom is used. A configuration was adopted in which the middle boom itself was lifted by a cylinder, or the lower boom or the upper boom was pushed out by a hydraulic cylinder inserted in the middle boom, respectively, to extend the boom.

In this configuration, since the hydraulic cylinder must be used to lift the middle boom and extend the lower boom and the upper boom, the extension amounts of the upper boom and the lower boom must be synchronized. is there. For this synchronization, a tuning mechanism composed of a chain, a wire or the like must be provided, which complicates the structure, complicates the assembling, and causes the weight of the lifting mechanism itself to be heavy.

Therefore, an aerial work vehicle having a structure in which the elevating mechanism itself is at least two hydraulic expansion / contraction mechanisms, and each hydraulic expansion / contraction mechanism is constructed by alternately assembling two hydraulic cylinders in parallel has been proposed (for example, a patent). Application 1991 336
No. 283). In this configuration, a pair of hydraulic cylinders are fixed in parallel, and the hydraulic expansion / contraction mechanism is configured so that the respective cylinder rods extend in opposite directions. Then, the tip of each cylinder rod is connected to the vehicle body and the lifting table, and the cylinder rod extends to deform the hydraulic expansion / contraction mechanism into an X-shape so that the lifting table can be moved up and down. In this case, each hydraulic cylinder in the hydraulic expansion / contraction mechanism and the hydraulic pressure source provided on the vehicle body are connected by a flexible high pressure hose, and the pressure oil is supplied by the high pressure hose. However, since each hydraulic cylinder also rises from the vehicle body as the lift rises, the high pressure hose must be slackened by the amount of rise, and the long high pressure hose is exposed to the outside of the hydraulic expansion and contraction mechanism. Not only is it unsightly, but this high-pressure hose is an obstacle when the hydraulic expansion mechanism is contracted. Also, since the high-pressure hose is bent and driven by the vertical movement of the lifting platform, it causes fatigue of the high-pressure hose made of rubber or resin material, and breakdowns such as breakage easily occur during long-term use. Met.

Further, two sets of hydraulic expansion / contraction mechanisms are arranged on the left and right sides of the vehicle body, and in order to raise the lifting platform vertically, pressure oil flows between the hydraulic expansion / contraction mechanisms to synchronize the extension amounts. It must be. For this synchronization, the left and right hydraulic expansion and contraction mechanisms must be connected by high-pressure hoses, and these high-pressure hoses are stressed so as to be twisted by the rotation of the hydraulic expansion and contraction mechanism. ..
Such stress causes failure of the high-pressure hose, hinders long-term use, and is troublesome for maintenance.

[0018]

Thus, if the hydraulic expansion / contraction mechanism has a structure similar to that of a hydraulic cylinder, the structure becomes extremely simple, and the lifting / lowering capability is improved by lifting the lifting platform by the cylinder rod of each hydraulic cylinder. However, it is necessary to connect the hydraulic expansion and contraction mechanisms that make up the lifting mechanism to the pressure oil generation source on the vehicle body with a long high-pressure hose. There is also the drawback of having to connect with. The handling of such a high-pressure hose is not only unattractive, but also rubber and resin are fatigued during long-term use, requiring regular maintenance and inspection, which is not preferable in terms of management. Therefore, it has a structure similar to a hydraulic cylinder that improves on the drawbacks of conventional work platforms, and it does not require a high-pressure hose connecting the hydraulic expansion mechanism and the pressure generation source, and both hydraulic expansion mechanisms. Development of a work vehicle was desired.

[0019]

SUMMARY OF THE INVENTION The present invention is directed to a movable vehicle body, a lift table which is located above the vehicle body and can be vertically moved up and down, and a lift mechanism which is interposed between the vehicle body and the lift table and can be vertically expanded and contracted. In an aerial work vehicle having a lift mechanism, the lifting mechanism includes at least a pair of hydraulic expansion / contraction mechanisms rotatably connected at the center, and each hydraulic expansion / contraction mechanism is composed of a pair of hollow inner slender outer cases arranged in parallel. The hydraulic cylinder is slidably inserted in each outer case, the tip of the cylinder rod of each hydraulic cylinder is connected to the outer case, and the base of one hydraulic cylinder of each hydraulic expansion mechanism is connected to the vehicle body. Connect the base of the other hydraulic cylinder to the lift,
The lifting mechanism is configured to have an X shape when viewed from the side, and by supplying hydraulic pressure to each hydraulic cylinder at the same time, each hydraulic cylinder is operated in synchronization with each outer case to lift the lifting platform. It provides an aerial work vehicle.

[0020]

In the present invention, the lifting mechanism is composed of a pair of hydraulic expansion / contraction mechanisms combined in an X shape, and each hydraulic expansion / contraction mechanism has a pair of square pipe-shaped outer cases arranged in parallel. A hydraulic cylinder is slidably inserted inside. The tip of each cylinder rod is connected to the outer case, and the base of each hydraulic cylinder is connected to the vehicle body and the lift. A synchronizing pipe is inserted through the inside of each cylinder rod, and the synchronizing pipe connects the hydraulic cylinder of one hydraulic expansion mechanism to the hydraulic cylinder of the other hydraulic expansion mechanism. When pressure oil is supplied from the base of the hydraulic cylinder connected to the vehicle body, the pressure oil simultaneously flows in each hydraulic cylinder, and the cylinder rods can be expanded and contracted in synchronization with each hydraulic cylinder. It is possible to raise the lifting platform by radially expanding it in a letter shape. In addition, the hydraulic cylinder of each hydraulic expansion mechanism has two types of inner diameter, large diameter and thin diameter, so that the discharge cross-sectional area of the large-diameter hydraulic cylinder and the pressure cross-sectional area of the small-diameter hydraulic cylinder are the same. Since the pressure oil discharged from the large-diameter hydraulic cylinder expands the small-diameter hydraulic cylinder, the expansion amounts of the large-diameter hydraulic cylinder and the small-diameter hydraulic cylinder are synchronized.

The center of the pair of hydraulic expansion / contraction mechanisms is rotatably connected by a swivel joint, and the pressure oil between the hydraulic expansion / contraction mechanisms is made to flow by the swivel joints. It freely rotates in an X shape at the center, and pressure oil for synchronization freely flows between the hydraulic cylinders. in this way,
Since the base of the hydraulic cylinder is connected to the vehicle body, pressure oil can be directly supplied to and discharged from the hydraulic cylinder, so that it is not necessary to route the high pressure hose between the vehicle body and the hydraulic expansion / contraction mechanism. In addition, since the flow of pressure oil between each hydraulic cylinder is performed by the swivel joint, the high pressure hose cannot be seen from the outside between the two hydraulic expansion / contraction mechanisms, and the appearance is simple. Since the hose is eliminated, the cause of failure is reduced.
In this way, it is no longer necessary to intervene a high-pressure hose between the hydraulic expansion and contraction mechanisms as in the past, and no unreasonable force such as twisting the high-pressure hose is generated, maintenance and inspection are easy, and long-term use is possible. Is possible.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, FIG. 1 is a perspective view of an elevation platform of an aerial work vehicle raised to a maximum height position as viewed obliquely from the rear, and FIG. 2 is an elevation platform raised to the maximum height. FIG. 3 is a side view of the state, FIG. 3 is a side view of the state where the elevator is lowered to the minimum height, and FIG. 4 is a rear view of the state where the elevator is lowered to the minimum height.

First, in these figures, a front wheel 2 and a rear wheel 3 are axially supported at the front and rear of a lower portion of a vehicle body 1 having a prime mover, a hydraulic pressure generating mechanism and the like built therein. The front wheel 2 can change its direction to the left and right, and the vehicle body 1 can freely move its position by driving the rear wheel 3. An elevating mechanism 4 assembled in an X shape on the upper surface of the vehicle body 1.
Is connected to the upper end of the elevating mechanism 4, and an elevating table 5 for mounting people and materials is connected. This elevator 5
A handrail 6 made of pipe is fixed around the upper surface of the pipe so that the worker does not drop. A control box 7 is provided on the front surface of the handrail 6 for storing operation levers, switches, and the like, and for operating the entire aerial work vehicle.
Is fixed. Further, two sets of kick mechanisms 8 are provided on the left and right of the center of the upper surface of the vehicle body 1 and are composed of gas springs and are always urged upward.

Next, the lifting mechanism 4 mounted on the vehicle body 1 comprises two sets of hydraulic expansion / contraction mechanisms 11 arranged on both left and right sides in the horizontal direction.
It is composed of twelve. These pair of hydraulic expansion and contraction mechanism 1
1, 1 and 12 are rotatably connected at the center thereof to form an X shape. Although these hydraulic expansion / contraction mechanisms 11 and 12 have exactly the same structure, the hydraulic expansion / contraction mechanism 11
Both 12 and 12 have a vertically inverted structure on the internal structure.

The hydraulic expansion / contraction mechanism 11 is constructed by connecting rectangular pipe-shaped outer cases 13 and 14 each having a rectangular cross section so that they are parallel to each other.
Flat plate-shaped roller boxes 17 and 18 are fixed to both ends of 14 so as to be parallel to each other. Inside each of the roller boxes 17 and 18, rollers and pins are arranged. One end opening of this outer case 13 (lower side in FIG. 1)
A guide rail 21 and a thick cylinder 25 are inserted in the outer case 13 so as to be slidable in the length direction of the outer case 13. Further, the other end opening of the outer case 14 (upper side in FIG. 1)
A guide rail 22 and a thin cylinder 26 are inserted in the outer case 14 so as to be slidable in the length direction of the outer case 14.

The hydraulic expansion / contraction mechanism 12 is constructed by connecting rectangular pipe-shaped outer cases 15 and 16 having a rectangular cross section so as to be parallel to each other.
Flat plate-shaped roller boxes 19 and 20 are fixed to both ends of 16 in parallel with each other. Inside each of the roller boxes 19 and 20, rollers and pins are arranged. One end opening of the outer case 15 (upper side in FIG. 1)
A guide rail 23 and a thick cylinder 27 are inserted in the outer case 15 so as to be slidable in the length direction of the outer case 15. Further, the other end opening of the outer case 16 (lower side in FIG. 1)
A guide rail 24 and a thin cylinder 28 are inserted in the outer case 16 so as to be slidable in the length direction of the outer case 16.

These guide rails 21, 22, 23,
Each of the 24 is made of a long angle member having a U-shaped cross section. The pair of guide rails 21 are aligned in the length direction of the thick cylinder 25, and the open ends of both guide rails 21 are welded to the peripheral surface of the thick cylinder 25, whereby the pair of guide rails 21 and the thick cylinder 25 are welded. 7 is assembled into a structure having a rectangular cross section as shown in FIG. In addition, the pair of guide rails 22
Aligns its length direction with the length direction of the thin cylinder 26,
By welding the open ends of both guide rails 22 to the peripheral surface of the thin cylinder 26, the pair of guide rails 22 and thin cylinder 26 are assembled into a structure having a rectangular cross section as shown in FIG. The length direction of the pair of guide rails 23 is aligned with the length direction of the thick cylinder 27, and the open ends of both guide rails 23 are welded to the circumferential surface of the thick cylinder 27, so that the pair of guide rails 23 are thick. The cylinder 27 is assembled into a structure having a rectangular cross section as shown in FIG. Further, the pair of guide rails 24 has a thin cylinder 28 in the longitudinal direction.
By aligning the guide rails 24 in the longitudinal direction and welding the open ends of both guide rails 24 to the peripheral surface of the thin cylinder 28 to form a structure in which the pair of guide rails 24 and the thin cylinder 28 form a rectangular cross section as shown in FIG. It is assembled.

The thick cylinder 25 is a thin cylinder 26.
Its outer diameter and inner diameter are thicker than
The thick cylinder 27 has a larger outer diameter and inner diameter than the thin cylinder 28. Each of the thick cylinders 25 and 27 and the thin cylinders 26 and 28 has a structure similar to that of a hydraulic cylinder, as will be described later, and each end (upper, left, right end in FIG. 1) has a block shape. The shaft stopper is formed integrally.

A shaft support 29 is fixed to the front side of the upper surface of the vehicle body 1 (left side in FIGS. 1, 2, and 3), and the rear side of the upper surface of the vehicle body 1 (in FIGS. 1, 2, and 3). The shaft support 30 is fixed to the right side). A shaft support 31 is fixed to the front of the lower surface of the lifting table 5, and a shaft support 32 is fixed to the rear of the lower surface of the lifting table 5. These shaft supports 2
9, 30, 31 and 32 are formed by bending a thin steel plate so that the outer shape thereof becomes a little trapezoid.
The distance between 9 and 30 and the distance between the shaft supports 31 and 32 are arranged to be substantially the same. A shaft stopper at the lower end of the thick cylinder 25 is inserted into the shaft support 29, and
The lower end of 5 and the pivot support 29 are rotatably connected by a pin 33. Also, the shaft support 32 has a thin cylinder 2
A shaft stopper at the upper end of 6 is inserted, and the lower end of the thin cylinder 26 and the shaft support 32 are rotatably connected by a pin 36. Similarly, a shaft stopper at the upper end of the thick cylinder 27 is inserted in the shaft support 31, and the upper end of the thick cylinder 27 and the shaft support 3
1 is rotatably connected by a pin 35. A shaft stopper at the lower end of the thin cylinder 28 is inserted into the shaft support 30, and the lower end of the thin cylinder 28 and the shaft support 30 are rotatably connected by a pin 34. The shaft supports 29 and 30 are fixed at positions deviated to the left and right with respect to the center axis of the vehicle body 1, and the shaft supports 31 and 32 are similarly lifted.
It is fixed at a position offset to the left and right with respect to the central axis of the lower surface of the. Although the hydraulic expansion / contraction mechanisms 11 and 12 have almost the same configuration, the hydraulic expansion / contraction mechanisms 11 and 12 are arranged so that the respective mechanisms are vertically symmetrical. That is, in the hydraulic expansion / contraction mechanism 11, the thick cylinder 25 is located on the lower side, whereas in the hydraulic expansion / contraction mechanism 12, the thick cylinder 27 is arranged on the upper side, and in the hydraulic expansion / contraction mechanism 11, the thin cylinder 26 is arranged.
Is arranged on the upper side, whereas in the hydraulic expansion / contraction mechanism 12, the thin cylinder 28 is arranged on the lower side.

Further, a horizontally projecting kick pin 57 is fixed to the center of the outer side surface of the hydraulic expansion / contraction mechanism 11, and a horizontally protruding kick pin 58 is fixed to the center of the outer side surface of the hydraulic expansion / contraction mechanism 12. There is. These kick pins 57 and 58 come into contact with the upper end of the kick mechanism 8 and assist the initial lifting of the lifting mechanism 4.

Next, FIG. 5 is a cross-sectional view showing the internal structure of one hydraulic expansion / contraction mechanism 11 which constitutes the lifting mechanism 4. In FIG. 5, each of the outer cases 13 and 14 has an elongated rectangular pipe shape with a rectangular cross section, and one side surface of the outer cases 13 and 14 are closely attached to each other so that they are integrated. is there. And the outer case 1
Flat roller boxes 17 and 18 are fixed to the side surfaces of both ends of the rollers 3 and 14, respectively. This outer case 1
The inside of 3 has a thick cylinder 25 from the left opening in FIG.
Is movably inserted, and a pair of guide rails 21 fixed above and below the thick cylinder 25 are fixed so as to cover the circumference of the thick cylinder 25, and the thick cylinder 25 and the guide rail 21 are integrated. It can be moved inside the outer case 13. And the roller box 17
The rollers 40 and 41 pivotally supported on the guide rail 21
The rollers 40 and 41 can move the guide rail 21 and the thick cylinder 25 with their moving directions regulated by contacting the outer circumference of the roller. This thick cylinder 2
Reference numeral 5 denotes a hollow pipe shape having a circular cross section. A thick rod 44 is inserted from the tip opening (right side in FIG. 5) of the thick cylinder 25 toward the inside, and at the tip of the thick rod 44. Is a block-shaped rod head 46
The rod head 46 is connected to the roller box 18 by a pin. Therefore, when pressure oil is supplied into the thick cylinder 25, the thick cylinder 25 tries to push out the thick rod 44, but since the rod head 46 is fixed to the roller box 18, the thick cylinder 25 and the guide rail 21 Will be pushed out from the outer case 13 to the left side in FIG.

In addition, inside the outer case 14, FIG.
A thin cylinder 26 is movably inserted from the middle right opening, and a pair of guide rails 22 fixed to the upper and lower sides of the thin cylinder 26 are fixed so as to cover the periphery of the thin cylinder 26. It is possible to move inside the outer case 14 together with the unit 22. The rollers 42 and 43 axially supported by the roller box 18 come into contact with the outer circumference of the guide rail 22, and the rollers 42 and 43 move the guide rail 22 and the thin cylinder 26 with their movement directions regulated. You can The thin cylinder 26 is in the shape of a hollow pipe having a circular cross section, and a thin rod 45 is inserted inward from the tip opening (left side in FIG. 5) of the thin cylinder 26. A block-shaped rod head 47 is fixed to the tip of the rod head 47, and the rod head 47 is connected to the roller box 17 by a pin. Therefore, when the hydraulic pressure is supplied to the thin cylinder 26, the thin cylinder 26 tries to push out the thin rod 45, but since the rod head 47 is fixed to the roller box 17, the thin cylinder 26 and the guide rail 22. Will be pushed out from the outer case 14 to the right side in FIG.

In this way, when hydraulic pressure is supplied to the thick cylinder 25 and the thin cylinder 26 inside the hydraulic expansion / contraction mechanism 11, the thick cylinder 25 and the thin cylinder 26 are pushed out from the outer cases 13 and 14, respectively, The distance between both ends of the cylinder 25 and the thin cylinder 26 can be changed to be large.

FIG. 6 is a sectional view showing the internal structure of the other hydraulic expansion / contraction mechanism 12 which constitutes the lifting mechanism 4. The sectional structure in FIG. 6 is substantially the same as the structure of the hydraulic expansion / contraction mechanism 11 shown in FIG. In the structure of the hydraulic expansion / contraction mechanism 12, the large diameter thick cylinder 27 is located at the upper portion, and the small diameter thin cylinder 28 is located at the lower portion. As can be seen in FIG. 6, each of the outer cases 15 and 16 has an elongated rectangular pipe shape with a rectangular cross section.
One side of 6 is closely contacted and connected so that both are integrated. Flat plate-shaped roller boxes 19 and 20 are fixed to the side surfaces of both ends of the outer cases 15 and 16, respectively.

A thick cylinder 27 is movably inserted into the outer case 15 from the left opening in FIG. 5, and a pair of guide rails 23 fixed to the upper and lower sides of the thick cylinder 27 surround the thick cylinder 27. The thick cylinder 27 and the guide rail 23 can be integrally moved in the outer case 15. The rollers 48 and 49 axially supported by the roller box 19 come into contact with the outer circumference of the guide rail 23, and the guide rail 23 and the thick cylinder 27 are restricted in their moving directions by the rollers 48 and 49 to move. You can The thick cylinder 27 is in the shape of a hollow pipe having a circular cross section, and a thick rod 52 is inserted inward from the tip opening (right side in FIG. 6) of the thick cylinder 27. A block-shaped rod head 54 is fixed to the tip of the rod head 54, and the rod head 54 is connected to the roller box 20 by a pin. Therefore, when the hydraulic pressure is supplied to the thick cylinder 27, the thick cylinder 27 tries to push out the thick rod 52, but since the rod head 54 is fixed to the roller box 20, the thick cylinder 27 and the guide rail 23. Will be pushed out from the outer case 15 to the left side in FIG.

In addition, inside the outer case 16, FIG.
A thin cylinder 28 is movably inserted from the middle right opening, and a pair of guide rails 24 fixed to the upper and lower sides of the thin cylinder 28 are fixed so as to cover the circumference of the thin cylinder 28. It is possible to move inside the outer case 16 integrally with 24. The rollers 50 and 51 axially supported by the roller box 20 come into contact with the outer circumference of the guide rail 24, and the guide rail 24 and the thin cylinder 28 are restricted in their moving directions by the rollers 50 and 51 to move. You can The thin cylinder 28 is in the shape of a hollow pipe having a circular cross section, and a thin rod 53 is inserted inward from the tip opening (left side in FIG. 5) of the thin cylinder 28. A block-shaped rod head 55 is fixed to the tip of the rod head 55, and the rod head 55 is connected to the roller box 19 by a pin. Therefore, when hydraulic pressure is supplied into the thin cylinder 28, the thin cylinder 28 tries to push out the thin rod 53, but since the rod head 55 is fixed to the roller box 19, the thin cylinder 28 and the guide rail 24 6 is pushed out from the outer case 16 to the right side in FIG.

In this way, when the hydraulic pressure is supplied to the thick cylinder 27 and the thin cylinder 28 inside the hydraulic expansion / contraction mechanism 12, the thick cylinder 27 and the thin cylinder 28 are pushed out from the outer cases 15 and 16, respectively. The distance between both ends of the cylinder 27 and the thin cylinder 28 can be changed to be large.

FIG. 7 shows a sectional structure taken along the line AA in FIG. As shown in this figure, the thick cylinder 25 on the lower side is set to have a larger outer diameter and inner diameter than the thin cylinder 26 on the upper side, and the guide rail 21 also has an outer shape with respect to the guide rail 22. Is set to a large value. However, since the guide rail 21 having a U-shaped cross section is welded to the thick cylinder 25 from above and below, the outer shape formed by the pair of guide rails 21 and the thick cylinder 25 is rectangular, and the outer shape is It is set to be slightly smaller than the inner shape of the outer case 13 so that the guide rail 21 and the thick cylinder 25 do not come into contact with the outer case 13 when moving. Similarly, the guide rail 22 having a U-shaped cross section is fixed to the upper and lower sides of the thin cylinder 26, and the outer shape formed by the guide rail 22 and the thin cylinder 26 is rectangular, and the outer shape thereof is the outer case 14. The inner shape is set to be slightly smaller than the inner shape so that it does not come into contact with the outer case 14 when the guide rail 22 and the thin cylinder 26 move.

Next, FIG. 8 shows the outer case 1 in FIG.
6 is an enlarged view of a portion of one of openings 3 and 14 (on the left side in FIG. 5). As can be seen from the figure, the guide rails 21 having a U-shaped cross section are fixed above and below the thick cylinder 25 so as to be parallel to the axial direction of the thick cylinder 25. It has a structure in which 25 are integrated. And
Rollers 40 and 41 are in contact with the upper and lower surfaces of the guide rail 21, and the rollers 40 and 41 hold the guide rail 21 so that the guide rail 21 can freely move in its length direction.

Next, FIG. 9 is a sectional view showing the internal structure of the thick cylinder 25 in FIG. The thick cylinder 25 is in the shape of a pipe having a cylindrical cross section with one end (on the right side in FIG. 9) opened. The thick cylinder 25 has guide rails 21 above and below the outer circumference of the thick cylinder 25 along its length.
Is stuck. Then, inside the thick cylinder 25, the piston 6 that makes airtight contact with the inner peripheral surface of the thick cylinder 25 is provided.
0 is slidably inserted, and the tip of a thick rod 44 inserted from the right opening of the thick cylinder 25 is connected to the right side of the piston 60. A ring-shaped cylinder cap 61 is airtightly fitted to the left end opening of the thick cylinder 25, and the inner peripheral surface of the cylinder cap 61 is airtight and slidable with respect to the outer peripheral surface of the thick rod 44. Are in contact. A block-shaped rod head 46 is connected to the right end of the thick rod 44, and the right end opening of the thick rod 44 is closed by the rod head 46. A tuning pipe 62 is inserted inside the thick rod 44 in the lengthwise direction, and the tip end (left side in FIG. 9) of the tuning pipe 62 penetrates the central axis of the piston 60. The end (right side in FIG. 9) is engaged with the side surface of the rod head 46. Further, the rod head 46 is formed with ports 64 and 65 for flowing hydraulic pressure, the port 64 is communicated with the internal space of the thick rod 44, and the port 65 is communicated with the internal space of the tuning pipe 62. There is. A port 63 for allowing hydraulic pressure to flow is formed at the base of the thick cylinder 25 (on the left side in FIG. 9), and the port 63 and the internal space of the pressure chamber of the thick cylinder 25 are connected by an oil supply passage 66. is there. Further, a conduction hole 67 for communicating the inner and outer circumferences of the thick rod 44 is opened at a position near the tip of the thick rod 44 and close to the piston 60.

Next, FIG. 10 is a sectional view showing the internal construction of the thin cylinder 26 in FIG. The thin cylinder 26 is in the shape of a pipe having a cylindrical cross section with one end (left side in FIG. 10) opened.
Guide rails 22 are fixed to the upper and lower portions of the outer periphery of 6 along the length direction thereof. A piston 70, which is in airtight contact with the inner peripheral surface of the thin cylinder 26, is slidably inserted into the thin cylinder 26. The piston 70 is inserted into the left end of the thin cylinder 26 from the left end opening. The tip of the thin rod 45 is connected. A ring-shaped cylinder cap 71 is airtightly fitted to the right end opening of the thin cylinder 26, and the inner peripheral surface of the cylinder cap 71 is airtight with respect to the outer peripheral surface of the thin rod 45.
Moreover, it is in slidable contact. A block-shaped rod head 47 is connected to the left end of the thin rod 45, and the left end opening of the thin rod 45 is closed by the rod head 47. A tuning pipe 72 is inserted through the thin rod 45 in the lengthwise direction, and the tip (right side in FIG. 10) of the tuning pipe 72 penetrates the central axis of the piston 70. The end (on the left side in FIG. 10) is engaged with the side surface of the rod head 47. Further, the rod head 47 is formed with ports 74 and 75 for flowing hydraulic pressure, the port 74 is communicated with the internal space of the thin rod 45, and the port 75 is communicated with the internal space of the tuning pipe 72. There is. Further, at a position near the tip of the thin rod 45 and close to the piston 70, there is a through hole 7 for communicating the inner and outer circumferences of the thin rod 45.
6 is opened.

Next, FIG. 11 is a sectional view showing the internal structure of the thick cylinder 27 in FIG. The thick cylinder 27 is in the shape of a pipe having a cylindrical cross section with one end (right side in FIG. 11) open.
Guide rails 23 are fixed to the upper and lower portions of the outer periphery of 7 along the length direction thereof. A piston 80, which is in airtight contact with the inner peripheral surface of the thick cylinder 27, is slidably inserted into the thick cylinder 27, and the piston 80 is inserted into the right side of the thick cylinder 27 from the right side opening. The tip of the thick rod 52 is connected. A ring-shaped cylinder cap 81 is airtightly fitted to the right end opening of the thick cylinder 27, and the inner peripheral surface of the cylinder cap 81 is airtight and slidable with respect to the outer peripheral surface of the thick rod 52. Are in contact. This thick rod 52
A block-shaped rod head 54 is connected to the right end of the, and the right end opening of the thick rod 52 is closed by this rod head 54. A tuning pipe 82 is inserted inside the thick rod 52 in the lengthwise direction, and the tip (left side in FIG. 11) of the tuning pipe 82 penetrates the central axis of the piston 80. Edge (Fig. 11
The right side in FIG. 4) is engaged with the side surface of the rod head 54. Ports 83 and 84 for flowing hydraulic pressure are formed in the rod head 54, the port 83 communicates with the internal space of the thick rod 52, and the port 84 communicates with the internal space of the tuning pipe 82. There is. Further, at a position near the tip of the thick rod 52 and close to the piston 80, a conduction hole 8 for communicating the inner and outer circumferences of the thick rod 52 is formed.
5 is opened.

Next, FIG. 12 is a sectional view showing the internal structure of the thin cylinder 28 in FIG. The thin cylinder 28 is in the shape of a pipe having a cylindrical cross section with one end (left side in FIG. 12) opened.
Guide rails 24 are fixed to the upper and lower portions of the outer circumference of the rail 8 along the length direction thereof. A piston 90, which is in airtight contact with the inner peripheral surface of the thin cylinder 28, is slidably inserted inside the thin cylinder 28. The piston 90 is inserted into the left end of the thin cylinder 28 from the left end opening. The tip of the thin rod 53 is connected. A ring-shaped cylinder cap 91 is airtightly fitted to the right end opening of the thin cylinder 28, and the inner peripheral surface of the cylinder cap 91 is airtight with respect to the outer peripheral surface of the thin rod 53.
Moreover, it is in slidable contact. A block-shaped rod head 55 is connected to the left end of the thin rod 53, and the right end opening of the thin rod 53 is closed by the rod head 55. A tuning pipe 92 is inserted through the thin rod 53 in the lengthwise direction, and the tip (right side in FIG. 12) of the tuning pipe 92 penetrates the central axis of the piston 90. The end (left side in FIG. 12) is engaged with the side surface of the rod head 55. Further, the rod head 55 is formed with ports 94 and 95 for flowing hydraulic pressure, the port 94 communicates with the internal space of the thin rod 53, and the port 95 communicates with the internal space of the tuning pipe 92. There is. A port 93 that communicates with the inside of the thin cylinder 28 is formed near the tip of the thin cylinder 28 (on the left side in FIG. 12) and close to the cylinder cap 91. One end of the refueling pipe 96 that has been connected is connected. The oil supply pipe 96 is arranged in the space between the thin cylinder 28 and the guide rail 24 and extends to the vicinity of the base of the thin cylinder 28.
It communicates with the port 97 near the root of. Further, a conduction hole 98 for communicating the inner and outer circumferences of the thin rod 93 is opened at a position near the tip of the thin rod 53 and close to the piston 90.

Next, FIG. 13 shows the cutting positions for showing the shapes of the inner cross sections of the thick cylinder 25 and the thin cylinder 26 described above. The cutting position of the thick cylinder 25 in FIG. 13 taken along the line BB is the same as the cutting position of FIG. 9 taken along the line BB.
This is the cutting position near the tip of the. The cutting position of the thin cylinder 26 in FIG. 13 taken along the line CC is the same as the cutting position of FIG. 10 taken along the line CC, and is the cutting position near the base of the thin cylinder 26. The sectional shape at the cutting position shown in FIG. 13 is shown in FIG. 14, and the sectional view taken along the line BB is shown in the lower part of the drawing.
5, the thick rod 44 and the tuning pipe 62 are arranged slightly concentrically. Of the space of the thick cylinder 25 partitioned in this way, the cross-sectional area of the donut-shaped portion formed by the thick cylinder 25 and the thick rod 44 is defined as X, and the donut-shaped portion formed by the thick rod 44 and the tuning pipe 62 is formed. Let Y be the cross-sectional area of the portion. A cross section taken along the line CC is shown in the upper part of the figure, and in this cross section, the thin cylinder 2
The cross section of the internal space of 6 is shown as it is, and the cross-sectional area of the internal space of the thin cylinder 26 is Z. In relation to the shapes of the thick cylinder 25, the thick rod 44, the tuning pipe 62, and the thin cylinder 26, the cross-sectional area Z is set to match the total of the cross-sectional areas X and Y. Similarly, the cross-sectional structures taken along arrows DD and EE in FIGS. 11 and 12 have the same relationship, and the total cross-sectional area in the arrow D-D cross-section is the cross-section in the arrow EE. Match the area.

Next, FIG. 15 shows a sectional structure of the rotary connecting body 38 provided at the center of the elevating mechanism 4 described above. As described above, the hydraulic expansion / contraction mechanism 11 is formed by closely assembling the outer case 13 and the outer case 14, and the thin outer cylindrical coupling ring 1 is formed on the inner surface thereof.
00 is fixed, and a ring-shaped inner connecting ring 101 is fixed to the tip of the outer connecting ring 100. The hydraulic expansion / contraction mechanism 12 is formed by closely fitting the outer cases 15 and 16 together.
A mounting ring 102 having a cylindrical shape is fixedly attached to the inner surface of each of 5 and 16. A ring-shaped outer ring 103 is in close contact with the tip of the inner connecting ring 101, and the inner connecting ring 101 and the outer ring 103 are fastened and fixed by bolts 106. In addition, a ring-shaped inner ring 104 is closely attached to the side surface of the mounting ring 102,
The attachment ring 102 and the inner ring 104 are fastened and fixed by bolts 107. Then, the outer ring 103
A plurality of bearings 105 are inserted in a groove formed between the inner periphery of the inner ring 104 and the outer periphery of the inner ring 104. The bearings 105 keep the outer ring 103 and the inner ring 104 from rotating smoothly. There is. In this way, both the hydraulic expansion / contraction mechanism 11 and the hydraulic expansion / contraction mechanism 12 are held by the outer connecting ring 100, the inner connecting ring 101, the mounting ring 102, etc. so as to be relatively rotatable in opposite directions, and in the left-right direction. It is regulated not to leave.

The outer coupling ring 100, the inner coupling ring 101, and the mounting ring 102 have hollow interiors, so that a cylindrical space is formed by these, and the inner space of the outer coupling ring 100 has a cylindrical shape. Outer joint 1
12 is housed therein, and an inner joint 113, which is also cylindrical, is inserted inside the mounting ring 102. The outer joint 112 and the inner joint 113 allow the hydraulic pressure to flow from one side to the other and can rotate with respect to each other.
14 are configured. Then, on the outer circumference of the outer connecting ring 100, the port insertion holes 1 are formed at four locations at equal intervals.
08, 109 (the other two places are not displayed in FIG. 15)
Are opened, and the ports 128 and 129 fixed to the outer joint 112 have port insertion holes 108 and 109.
It passes through and protrudes to the outside. Also, the mounting ring 10
Port insertion holes 110 and 111 (the other two positions are not shown in FIG. 15) are opened at four positions on the outer circumference of the port 2 at equal intervals, and the port 132 and the port fixed to the inner joint 113 are provided. 133 is the port insertion holes 110, 1
It passes through 11 and protrudes to the outside. With this configuration,
Pressure oil from port 128 and port 129 is applied to port 13
2, it can be flowed to the port 133.

Next, FIG. 16 shows the swivel joint 1 described above.
14 shows the internal structure of 14. The structure of the swivel joint 114 has been conventionally known, and it is possible to cause pressure oil to flow between the outer joint 112 and the inner joint 113 that rotate with each other while not hindering the rotation in the axial direction. The outer joint 112 has a cylindrical shape, and an inner joint 113 having a cylindrical shape is airtightly and rotatably inserted inside the outer joint 112. The inner circumferential surface of the outer joint 112 has four groove-shaped inner annular grooves 116, 117, 118, 1
19 are formed by cutting at equal intervals, and the inner joint 113
4 outer annular grooves 120, 121, 122, 1 on the outer periphery of
23 are cut and formed at equal intervals. This inner annular groove 116
The outer annular groove 120 faces the inner annular groove 117, the outer annular groove 121 faces the inner annular groove 117, the outer annular groove 122 faces the inner annular groove 118, and the outer annular groove 123 faces the inner annular groove 119. Are opposed to each other, and by such a combination, four ring-shaped hydraulic flow spaces are formed inside the swivel joint 114. Then, four ports 128, 129, 130, 131 are provided on the outer circumference of the outer joint 112.
(Ports 130 and 131 are not shown in FIG. 16, but are shown in FIGS. 17 and 18) are radially projected so that they can be connected to the hydraulic hose. Then, inside the inner joint 113, there are four oil guide passages 124, 125, 126 which are parallel to each other in the transverse section (state of FIG. 16) and are radially separated by 90 degrees in the longitudinal section (state of FIG. 18). ,
127 is formed, and the oil guide passage 124 is formed in the outer annular groove 120.
The oil guide passage 125 is connected to the outer annular groove 122, the oil guide passage 126 is connected to the outer annular groove 121, and the oil guide passage 127 is connected to the outer annular groove 123. Then, these oil passages 124,
125, 126, 127 extend to the vicinity of the root of the inner joint 113 (on the right side in FIG. 16), and the inner joint 113
Are radially oriented so as to form a cross shape near the root of each of the ports, and ports 132, 133, 134, and 135 (ports 134 and 135 are shown in FIG. 16 for connecting to hydraulic hoses and the like at their respective ends). No, FIG. 17, FIG.
8) is stuck. With such a configuration, the outer joint 112 and the inner joint 113 can relatively rotate, and the port 128 is provided in the inner annular groove 11.
6, the outer annular groove 120, the oil guide passage 124, and the port 13
Always in communication with 2. Similarly, port 129 is port 133, port 130 is port 134, and port 13
1 always communicates with the port 135. This communicating structure is easy to understand with reference to FIG.

FIG. 18 is a sectional view taken along the line F--F in FIG. 16, in which four oil guide passages 124, 12 are provided inside the inner joint 113 at 90 ° intervals.
5, 126, 127 are formed. The ports 128, 129, 130, 131 are also fixed to the outer periphery of the outer joint 112 at 90 degrees apart from each other.
The inner annular grooves 116 and 117 each have a ring shape,
118, 119 and outer annular grooves 120, 121, 122, 1
It communicates with the space formed by 23. FIG. 18 shows a state in which the port 131 communicates with the space formed by the inner annular groove 119 and the outer annular groove 123. Similarly, the other inner annular grooves 116, 117, 11
8, the ports 128, 129, 1 in the space formed by the outer annular grooves 120, 121, 122 as in FIG.
30 communicate with each other. Next, FIG. 19 shows a state before combining the hydraulic expansion / contraction mechanisms 11 and 12 in this embodiment. Although not shown in FIGS. 1 to 6, four hydraulic hoses 138, 137, 139 and 140 are radially connected to the outer circumference of the outer connection ring 100. Of these, the hydraulic hoses 138 and 139 are communicated with the ports 64 and 65 provided in the rod head 46,
The hydraulic hoses 139 and 140 are connected to the ports 74 and 75 provided on the rod head 47. Similarly, four hydraulic hoses 141, 1 are radially provided on the outer periphery of the mounting ring 102.
42, 143, 144 are connected to the hydraulic hose 14
1, 142 are ports 83, 8 provided on the rod head 54
4 and hydraulic hoses 143 and 144 communicate with ports 94 and 95 formed in the rod head 55.

Next, FIG. 20 shows the construction of the hydraulic circuit in this embodiment. A hydraulic pump 147 is installed in a prime mover 149 such as a motor and an engine built in the vehicle body 1 described above.
Is connected to the suction side of the hydraulic pump 147 in communication with an oil tank 148 storing pressure oil, and the discharge side of the hydraulic pump 147 is connected to a switching valve 150 for switching the circuit between three directions. The return side of the switching valve 150 is communicated with the oil tank 148. The port 63 is connected to one output of the switching valve 150, and the switching valve 15
The other output of 0 is connected to the port 97.

As described above, the swivel joint 114 forms a hydraulic circuit between the hydraulic expansion / contraction mechanisms 11 and 12. Ie port 6
5, one end of the hydraulic hose 137 is connected, the other end of the hydraulic hose 137 is connected to the hydraulic hose 141 via the outer joint 112 and the inner joint 113, and the end of the hydraulic hose 141 is connected to the port 84. is there. One end of the hydraulic hose 138 is connected to the port 64, and the other end of the hydraulic hose 138 is connected to the hydraulic hose 143 via the outer joint 112 and the inner joint 113.
The end of the hydraulic hose 143 is connected to the port 95.
Further, the tip of a hydraulic hose 139 is connected to the port 75, and the other end of the hydraulic hose 139 is connected to the outer joint 11.
2. The hydraulic hose 142 is connected via the inner joint 113, and the end of the hydraulic hose 142 is connected to the port 83. Further, the tip of the hydraulic hose 140 is connected to the port 74, the other end of the hydraulic hose 140 is connected to the hydraulic hose 144 via the outer joint 112 and the inner joint 113, and the end of the hydraulic hose 144 is the port. It is connected to 94.

Next, the operation of this embodiment will be described.

In order to operate this aerial work vehicle, first, the prime mover 149 housed in the vehicle body 1 is started by a battery or gasoline, and the prime mover 149 drives the hydraulic pump 147. The hydraulic pump 147 sucks the pressure oil from the oil tank 148 and supplies the pressure oil to each part of the work vehicle at high places, whereby various operations can be performed. The operation of this aerial work vehicle is performed by an operator on the elevator 5 operating a lever or the like of the control box 7.

First, the procedure of the operation of lifting the lifting platform 5 to the maximum height position as shown in FIG. 2 from the state where the lifting platform 5 is lowered to the lowest position as shown in FIG. 3 will be described. In this raising operation, the switching valve 150 is switched to the "positive side", and the pressure oil generated from the hydraulic pump 147 is transferred to the port 63.
Supply to. Then, the supplied pressure oil is supplied to the pressure chamber of the thick cylinder 25 after passing through the oil supply passage 66 formed inside the thick cylinder 25. Therefore, the supplied pressure oil expands inside the thick cylinder 25, pushing the piston 60 in FIG. 9 to the right in FIG. 9, and pushing the thick rod 44 out of the thick cylinder 25. .. The pressure oil supplied to the pressure chamber of the thick cylinder 25 simultaneously passes through the inside of the tuning pipe 62 and flows out of the port 65, and passes through the hydraulic hose 137, the swivel joint 114, and the hydraulic hose 141 to the port 84. Will be supplied to. The pressure oil flowing into the port 84 passes through the tuning pipe 82 and is supplied to the pressure chamber inside the thick cylinder 27. Therefore, the supplied pressure oil expands inside the thick cylinder 27, pushing the piston 80 in FIG. 11 rightward in FIG. 11, and pushing the thick rod 52 out of the thick cylinder 27. ..

Thus, in FIG. 9, the thick cylinder 2
5, the thick rod 44 is pushed out, and at the same time, in FIG. 11, the thick rod 52 is pushed out from the thick cylinder 27. However, the rod head 46 fixed to the thick rod 44 is connected to the roller box 18,
Since the rod head 54 fixed to the thick rod 52 is connected to the roller box 20, the thick rod 4
The positions of the cylinders 4 and 52 cannot be changed with respect to the outer cases 13 and 15, and the thick cylinders 25 and 27 are relatively moved so as to project to the outside from the outer cases 13 and 15. .. Therefore, as shown in FIG. 5, the thick cylinder 25 and the guide rail 21 are
While being guided by 41, it is pushed out from the inside of the outer case 13 to the left in FIG. Further, as shown in FIG. 6, the thick cylinder 27 and the guide rail 23 are provided with rollers 48, 49.
6 is pushed out from the inside of the outer case 15 to the left in FIG.

Next, when the piston 60 moves to the right in FIG. 9 inside the thick cylinder 25 as described above, the volume of the discharge chamber on the right side of the thick cylinder 25 in FIG. 9 is reduced. Therefore, the pressure oil stored inside the thick cylinder 25 and outside the thick rod 44 and in the space on the right side of the piston 60 passes through the through hole 67 and flows into the thick rod 44. Oil is port 64
More outflow. The pressure oil flowing out from the port 64 is transmitted to the port 95 via the hydraulic hose 138, the swivel joint 114, and the hydraulic hose 143, passes through the tuning pipe 92, and is supplied to the space of the pressure chamber of the thin cylinder 28. Therefore, the supplied pressure oil expands in the pressure chamber of the thin cylinder 28, and acts to push the piston 90 leftward in FIG. 12 with respect to the thin cylinder 28. Similarly, when the piston 80 moves to the right in FIG. 11 inside the thick cylinder 27, the volume of the discharge chamber on the right side of the thick cylinder 27 in FIG. 11 is reduced. Therefore, the pressure oil stored in the space on the right side of the piston 80 inside the thick cylinder 27 and outside the thick rod 52 passes through the through hole 85 and passes through the thick rod 52.
And then the pressure oil flows out through the port 83. The pressure oil flowing out from the port 83 is supplied to the port 75 via the hydraulic hose 142, the swivel joint 114, and the hydraulic hose 139. Therefore, the supplied pressure oil passes through the tuning pipe 72 and is supplied to the space of the pressure chamber of the thin cylinder 26. Therefore, the supplied pressure oil expands in the pressure chamber of the thin cylinder 26 and pushes the piston 70 to the left in FIG.

Thus, in FIG. 10, the thin rod 45 is pushed out from the thin cylinder 26, and at the same time, in FIG. 12, the thin rod 53 is pushed out from the thin cylinder 28. However, since the rod head 47 fixed to the thin rod 45 is connected to the roller box 17, and the rod head 55 fixed to the thin rod 53 is connected to the roller box 19, the thin rod 45, The position of 53 cannot be changed with respect to the outer cases 14 and 16, and is relatively thin cylinders 26 and 28.
Will be moved so as to project from the outer cases 14 and 16 to the outside. Therefore, as shown in FIG. 5, the thin cylinder 26 and the guide rail 22 are
As shown in FIG.
It is pushed to the right in the inside. Further, as shown in FIG. 6, the thin cylinder 28 and the guide rail 24 are
While being guided by 51, it is pushed rightward in FIG. 6 from the inside of the outer case 16.

Further, in FIG. 10, the thin cylinder 26
When the piston 70 moves leftward in the inside, the pressure oil remaining in the space of the discharge chamber on the left side of the piston 70 between the inside of the thin cylinder 26 and the outside of the thin rod 45 causes the thin rod to flow from the through hole 76. It flows into the inside of 45 and flows out from the port 74 to the outside. The pressure oil flowing out from the port 74 is transmitted to the port 94 via the hydraulic hose 140, the swivel joint 114, and the hydraulic hose 144. The pressure oil that has flowed into the thin rod 53 from the port 94 is supplied from the through hole 98 to the inside of the thin cylinder 28 and the thin rod 53.
It will flow into the space between. At the same time, in FIG. 12, when the piston 90 moved leftward in the thin cylinder 28, it remained in the space of the discharge chamber on the left side of the piston 90 between the inside of the thin cylinder 28 and the outside of the thin rod 53. The pressure oil is discharged to the outside of the thin cylinder 28 through the through hole 93. In this way, the pistons 70, 90
As the pressure oil remaining on the discharge side of the thin cylinders 26 and 28 is regulated in its flow path by sliding, the both are mixed and discharged from the port 93, and the oil supply pipe 96 and the port 97. After passing through the switching valve 150, the oil is returned to the oil tank 148.

As described above, when the pressure oil is supplied to the port 63, the pressure oil flows to the respective parts of the hydraulic expansion / contraction mechanisms 11 and 12, and the thick cylinders 25 and 27 simultaneously move to the outer cases 13 and 1.
Extruded from 5. These thick cylinders 25 and 27
The pressure oil discharged from each of the two cylinders is transmitted to the thin cylinders 26 and 28, and the thin cylinder 2
6 and 28 are interlocked and pushed out from the outer cases 14 and 16. In this way, the thick cylinders 25 and 27 and the thin cylinders 26 and 28 are simultaneously extended from the respective ends of the hydraulic expansion / contraction mechanisms 11 and 12 by the pressure oil supplied to the port 63 at one place. Both ends of the hydraulic expansion / contraction mechanisms 11 and 12 radiate around 38.

When the thick cylinders 25 and 27 and the thin cylinders 26 and 28 are operated, as shown in FIG. 14, the thick thick cylinder 25 and the thin thin cylinder 2 have a large diameter.
6, and the relation between the thick thick cylinder 27 and the thin fine cylinder 28, the cross-sectional area correlation between them is the sum of the cross-sectional areas of the thick cylinders 25 and 27 on the discharge side (X +
Y) is equal to the cross-sectional area Z on the pressure side of the thin cylinders 26, 28 having a small diameter. Therefore, the supply amount of the pressure oil discharged when the thick cylinder 25 extends with respect to the thick rod 44 is proportional to the cross-sectional area (X + Y), and at the same time, the thin cylinder 28 extends with respect to the thin rod 53. The pressure oil required at this time is proportional to the cross-sectional area Z. Cross-sectional area of both ((X +
Since Y) and Z) are the same, as a result, the extension amount of the thick cylinder 25 and the extension amount of the thin cylinder 28 are the same, and the thick cylinder 25 and the thin cylinder 28 move with the same extension amount. .. The supply amount of the pressure oil discharged when the thick cylinder 27 extends with respect to the thick rod 52 is proportional to the cross-sectional area (X + Y), and at the same time when the thin cylinder 26 extends with respect to the thin rod 45. The pressure oil required for is proportional to the cross-sectional area Z. Since the cross-sectional areas ((X + Y) and Z) of both are the same, as a result, the extension amount of the thick cylinder 27 and the extension amount of the thin cylinder 26 are the same, and the thick cylinder 27 and the thin cylinder 26 are synchronously the same. It will move with the extension amount of.
For this reason, the thick cylinders 25 and 27 and the thin cylinders 26 and 28 are expanded by the same expansion amount.

However, as shown in FIG.
In the lowermost position, the hydraulic expansion / contraction mechanisms 11 and 12 are arranged in parallel, and the thick cylinders 25 and 27, the thin cylinder 26, and the thin cylinder 28 are parallel to each other with a space therebetween. In addition, thick cylinders 25, 2
7. Since the tips of the thin cylinders 26 and 28 are connected to the shaft supports 29, 30, 31 and 32, respectively, the thick cylinders 25 and 27 and the thin cylinders 26 and 28 are connected.
Acts to extend from the outer cases 13, 14, 15, and 16, but the acting force does not act as a stress to directly lift the lifting platform 5. However, in the initial operation, the hydraulic expansion / contraction mechanisms 11 and 12 are positioned in parallel, and the thick cylinder 25,
Since the axes of the thin cylinders 27 and the thin cylinders 26 and 28 are slightly apart in the horizontal direction, this distance acts as a component force directed upward, and the lifting platform 5 is lifted. Furthermore, the kick mechanism 8 is always biased upward,
On the upper surface of the kick mechanism 8, kick pins 57 and 58 are provided, respectively.
Since they are in contact with each other, the urging force of the kick mechanism 8 acts to lift the kick pins 57 and 58 and the hydraulic expansion / contraction mechanisms 11 and 12. In this way, thick cylinder 2
5, 27, the hydraulic expansion / contraction mechanisms 11 and 12 are slightly lifted upward by the total of the component force in the vertical direction generated from the thin cylinders 26 and 28 and the assisting force of the kick mechanism 8, and the deformed X-shape is crushed from above and below. Changes to. At this time, since the bearing 105 is interposed between the outer connecting ring 100 and the mounting ring 102 in the rotating connecting body 38, the two can freely rotate with respect to each other, and thus the outer connecting ring 100 and the inner connecting ring 101. The hydraulic expansion / contraction mechanism 11 to which the outer ring 103 is connected and the hydraulic expansion / contraction mechanism 12 to which the mounting ring 102 and the inner ring 104 are connected can rotate in mutually opposite directions. In this way, the hydraulic expansion / contraction mechanisms 11 and 12 are relatively rotated in opposite directions, and the hydraulic expansion / contraction mechanisms 11 and 12 are not prevented from changing into the X-shape. At the same time, the thin cylinder 26 and the thick cylinder 27 are also in the outer case 1 respectively.
Because it is extruded from Nos. 4 and 15, the thick cylinder 2 described above
5. In combination with the extension force of the thin cylinder 28, the hydraulic expansion / contraction mechanisms 11 and 12 have the four thick cylinders 25 and 27 and the thin cylinders 26 and 28 radially with the pivotal connecting body 38 connecting them as a central axis. It will be expanded into an X shape.

When the hydraulic expansion / contraction mechanisms 11 and 12 are slightly changed to the X-shape in this way, the outer cases 13, 14, 15, 16 are formed.
The extension forces of the thick cylinders 25 and 27 and the thin cylinders 26 and 28 that are pushed out further generate a component force that acts in the up-down direction, and act to lift the lifting platform 5 upward. In this way, the hydraulic expansion / contraction mechanisms 11 and 12 that constitute the lifting mechanism 4 change from a state of being folded in parallel to an X shape in which the top and bottom are crushed, and then change to an X shape, and the lifting platform 5 is raised to the maximum height position. 1, it will rise to the state shown in FIG. In this order, the thick cylinders 25 and 27 and the thin cylinder 2 extended from the hydraulic expansion and contraction mechanisms 11 and 12 are arranged.
The length between both ends of 6, 28 is the outer case 13, 14, 1
It extends up to about three times the length of only 5,16. As a result,
The lift 5 is lifted to a position higher than the vehicle body 1. When the lifting table 5 is lifted to a predetermined height, when the operator returns the switching valve 150 to "neutral", the port 63
The pressure oil supplied to the pump stops its flow, and the lift 5 is held at the lifted height. In this way, by stopping the flow of the pressure oil, the lifting table 5 maintains its height, and in this state, the worker on the lifting table 5 can perform various construction work and civil engineering work at a high place.

Next, in order to lower the elevating table 5 from the raised position, the switching valve 150 is switched to the "reverse" side, contrary to the above, and the pressure oil from the hydraulic pump 147 is transferred to the port 97.
Supply to. The supplied pressure oil passes through the oil supply pipe 96 and the port 93 and is supplied to the space on the discharge side of the thin cylinder 28, flows between the inside of the thin cylinder 28 and the outside of the thin rod 53, and causes the piston 90 to move. It moves to the right inside, and acts so as to push the thin rod 53 into the thin cylinder 28. At the same time, a part of the pressure oil that has flowed in passes through the conduction hole 98, flows inside the thin rod 53, and is discharged from the port 94. The pressure oil discharged from the port 94 is hydraulic hose 144, swivel joint 1
It flows into the internal space of the thin rod 45 via 14, the hydraulic hose 140, and the port 74. The pressure oil that has flowed into the thin rod 45 passes through the through hole 76 and is supplied to the space between the inner circumference of the thin cylinder 26 and the outer circumference of the thin rod 45 to move the piston 70 to the right in FIG. ..

In the thin cylinder 28, the piston 90 and the thin rod 53 are moved rightward in FIG. 12, but the rod head 5 fixed to the thin rod 53 is used.
5 is connected to the roller box 19, the thin cylinder 28 and the guide rail 24 are relatively
It is pulled into the inside of the outer case 16 while being guided by 0 and 51. Similarly, in the thin cylinder 26, the piston 70 and the thin rod 45 are moved to the right in FIG.
Since 7 is fixed to the roller box 17, the thin rod 45 and the piston 70 do not move, and the thin cylinder 2
6. The guide rail 22 is retracted into the outer case 14 while being guided by the rollers 42 and 43.

As described above, when the piston 90 moves to the right inside the thin cylinder 28 as shown in FIG. 12, the pressure oil remaining in the pressure chamber of the thin cylinder 28 passes through the tuning pipe 92. It is discharged from the port 95.
The pressure oil discharged from this port 95 is the hydraulic hose 14
3, the swivel joint 114 and the hydraulic hose 138 are passed to flow into the port 64, and then the tuning pipe 62 and the conduction hole 67 are passed to flow into the discharge chamber of the thick cylinder 25 as shown in FIG. Therefore, the pressure oil is thick cylinder 2
It expands in the discharge chamber 5 and acts to move the piston 60 leftward in FIG. Further, as shown in FIG. 10, when the piston 70 moves rightward inside the thin cylinder 26, the pressure oil remaining in the pressure chamber of the thin cylinder 26 passes through the tuning pipe 72 and is discharged from the port 75. .. The pressure oil discharged from the port 75 is hydraulic hose 139, swivel joint 114, hydraulic hose 142.
11 into the port 83, and passes through the tuning pipe 82 and the conduction hole 85 as shown in FIG.
Pour into the discharge chamber of. Therefore, the pressure oil expands in the discharge chamber of the thick cylinder 27, and acts to move the piston 80 leftward in FIG.

In the thick cylinder 25, the piston 60 and the thick rod 44 are moved leftward in FIG. 9, but the rod head 46 fixed to the thick rod 44 is used.
Is connected to the roller box 18, the relatively thick cylinder 25 and the guide rail 21 are
While being guided by 41, it is retracted inside the outer case 13. Similarly, in the thick cylinder 27, the piston 8
0 and the thick rod 52 are moved to the right in FIG. 11, but since the rod head 54 fixed to the thick rod 52 is fixed to the roller box 20, the thick rod 52 and the piston 80 do not move and the thick rod 52 does not move. Cylinder 27,
The guide rail 23 is retracted inside the outer case 15 while being guided by the rollers 48 and 49.

In this way, the thick cylinders 25 and 27 and the thin cylinder 2 which are radially expanded like the X-shape are formed.
6 and 28 are retracted inside the outer cases 13, 14, 15 and 16, respectively, and the distance between the tips of the thick cylinder 25 and the thin cylinder 26 and the distance between the tips of the thick cylinder 27 and the thin cylinder 28 are reduced. The length of the X-shape formed by the hydraulic expansion / contraction mechanisms 11 and 12 is gradually reduced, and the elevating mechanism 4 changes from the top and bottom to the crushed X-shape. At this time, the movement amounts of the thick cylinders 25, 27 and the thin cylinders 26, 28 housed in the outer cases 13, 14, 15, 16 are in synchronization with each other.
7. The thin cylinders 26 and 28 are stored at the same speed. Therefore, the lifting table 5 placed on the upper part of the lifting mechanism 4 is gradually lowered. Then, the guide rail 21 and the thick cylinder 25 are placed inside the outer case 13,
The thin cylinder 26 and the guide rail 22 are inside the outer case 14, the guide rail 23 and the thick cylinder 27 are inside the outer case 15, and the guide rail 24 and the thin cylinder 28 are inside.
As shown in FIG.
As shown in FIG. 4, the lifting platform 5 descends to the lowest position approaching the upper surface of the vehicle body 1 and stops its operation. afterwards,
By returning the switching valve 150 to the "neutral" state, the function of lowering the work platform for high places is stopped.

Since the present invention is configured as described above, the elevating mechanism can move the hydraulic cylinder housed in the outer case having the shape of a square pipe, and the elevating table can be expanded and contracted in an X shape. Can be raised or lowered. And, because the base of the hydraulic cylinder is connected to the vehicle body or lift, and the hydraulic expansion and contraction mechanism is connected by a swivel joint, it is not necessary to slacken a long high-pressure hose as in the conventional case, and the structure is extremely simple. Becomes Since it is no longer necessary to handle the high pressure hose, manufacturing and maintenance are facilitated, and long-term use is possible.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing an aerial work vehicle according to an embodiment of the present invention.

FIG. 2 is a side view showing a state in which a lifting platform of an aerial work vehicle is lifted to a maximum height position.

FIG. 3 is a side view showing a state in which the lift of the aerial work vehicle is lowered to the minimum height position.

FIG. 4 is a rear view showing a state in which the lifting platform of the aerial work vehicle is lowered to the lowest height position.

FIG. 5 is a cross-sectional view showing the structure of one set of hydraulic expansion / contraction mechanisms that constitute the lifting mechanism.

FIG. 6 is a cross-sectional view showing the structure of the other pair of hydraulic expansion / contraction mechanisms that constitute the lifting mechanism.

FIG. 7 is a cross-sectional view showing the hydraulic expansion / contraction mechanism in FIG.

FIG. 8 is a partially cutaway assembly view showing the internal structure of one hydraulic expansion / contraction mechanism.

FIG. 9 is a sectional view showing a structure of a thick cylinder of one hydraulic expansion / contraction mechanism.

FIG. 10 is a sectional view showing a structure of a thin cylinder of one hydraulic expansion / contraction mechanism.

FIG. 11 is a sectional view showing the structure of a thick cylinder of the other hydraulic expansion / contraction mechanism.

FIG. 12 is a sectional view showing the structure of a thin cylinder of the other hydraulic expansion / contraction mechanism.

FIG. 13 is an explanatory diagram showing positions at which the hydraulic expansion mechanism is broken to show the structure of the hydraulic expansion mechanism.

FIG. 14 is an explanatory diagram showing a cross-sectional area of the hydraulic expansion / contraction mechanism that is broken in FIG.

FIG. 15 is a cross-sectional view of a rotary conduction mechanism that connects two sets of hydraulic expansion / contraction mechanisms.

FIG. 16 is a cross-sectional view showing the structure of a swivel joint.

FIG. 17 is an explanatory view showing an oil passage formed in the swivel joint.

FIG. 18 is a cross-sectional view of the swivel joint taken along the line FF in FIG.

FIG. 19 is an exploded perspective view showing pipes connected to two sets of hydraulic expansion / contraction mechanisms.

FIG. 20 is a hydraulic circuit diagram showing a flow path of hydraulic pressure supply in the present embodiment. 1 Vehicle Body 4 Lifting Mechanism 5 Lifting Table 11 Hydraulic Expansion / contraction Mechanism 12 Hydraulic Expansion / contraction Mechanism 25 Thick Cylinder 26 Thin Cylinder 27 Thick Cylinder 28 Thin Cylinder 38 Rotating Connection Body 44 Thick Rod 45 Thin Rod 52 Thick Rod 53 Thin Rod 60 Piston 62 Tuning Pipe 70 piston 72 tuning pipe 80 piston 82 tuning pipe 90 piston 92 tuning pipe 100 outer connecting ring 102 mounting ring 112 outer joint 113 inner joint 114 swivel joint 116 inner annular groove 117 inner annular groove 118 inner annular groove 119 inner annular groove 120 outer annular Groove 121 Outer annular groove 122 Outer annular groove 123 Outer annular groove 124 Oil guide 125 125 Oil guide 126 Oil guide 127 Oil guide 137 Hydraulic hose 138 Hydraulic hose 139 Hydraulic hose 140 Hydraulic hose 14 Hydraulic hoses 142 Hydraulic hoses 143 Hydraulic hoses 144 Hydraulic Hose

Claims (9)

[Claims] 1. An aerial work vehicle having a movable vehicle body, an elevating platform located above the vehicle body and capable of vertically elevating, and an elevating mechanism capable of vertically expanding and contracting interposed between the vehicle body and the elevating platform. , The elevating mechanism is composed of at least a pair of hydraulic expansion / contraction mechanisms that are rotatably connected at the center, and each hydraulic expansion / contraction mechanism is composed of a pair of inner hollow elongated outer cases arranged in parallel. The hydraulic cylinders are slidably inserted, the tip of the cylinder rod of each hydraulic cylinder is connected to the outer case, the base of one hydraulic cylinder of each hydraulic expansion mechanism is connected to the vehicle body, and the base of the other hydraulic cylinder is moved up and down. Connected to the table, the lifting mechanism is X when viewed from the side.
An aerial work vehicle that is configured to have a letter shape, and by supplying hydraulic pressure to each hydraulic cylinder at the same time, each hydraulic cylinder is operated in synchronization from each outer case to lift the lifting platform. 2. A long and narrow guide rail is fixed to the side surface of each hydraulic cylinder along the lengthwise direction, and the guide rail is brought into contact with the outer circumference of the guide roller pivotally supported near the opening of each outer case, and 2. The aerial work vehicle according to claim 1, wherein the hydraulic cylinder and the guide rail are held so as to be retractable from the outer case. 3. A pair of outer casings constituting the lifting mechanism are rotatably connected by a swivel joint, and the pair of hydraulic cylinders housed in one outer casing and the other outer casing are housed by the swivel joint. The aerial work vehicle according to claim 1, wherein the pressure oil is caused to flow between the pair of hydraulic cylinders. 4. A pair of hydraulic cylinders forming each hydraulic expansion / contraction mechanism, wherein one of the hydraulic cylinders has a large pressure cross-sectional area and the other hydraulic cylinder has a small pressure cross-sectional area. The aerial work vehicle according to claim 1, 2, or 3. 5. A pressure cross-sectional area of one of the pair of hydraulic cylinders constituting each hydraulic expansion mechanism is formed to have a large diameter and a pressure cross-sectional area of the other hydraulic cylinder is formed to have a small diameter. Connect the base of the large diameter hydraulic cylinder of the hydraulic expansion / contraction mechanism to one side of the vehicle body, and connect the base of the small diameter hydraulic cylinder of the other hydraulic expansion / contraction mechanism to the other side of the vehicle body. The base of the hydraulic cylinder is connected to the other of the lifts, and the base of the large diameter hydraulic cylinder of the other hydraulic expansion mechanism is connected to one of the lifts. Aerial work vehicle. 6. An aerial work vehicle having a movable vehicle body, an elevating platform that is located above the vehicle body and can be vertically moved up and down, and an elevating mechanism that is interposed between the vehicle body and the vertically movable platform and can be vertically expanded and contracted. , The elevating mechanism is composed of at least a pair of hydraulic expansion / contraction mechanisms that are rotatably connected at the center, and each hydraulic expansion / contraction mechanism is composed of a pair of inner hollow elongated outer cases arranged in parallel. The hydraulic cylinders are slidably inserted, the tip of the cylinder rod of each hydraulic cylinder is connected to the outer case, the base of one hydraulic cylinder of each hydraulic expansion mechanism is connected to the vehicle body, and the base of the other hydraulic cylinder is raised and lowered. Connected to the table, the lifting mechanism is X when viewed from the side.
The cylinder rod of each hydraulic cylinder is in the shape of a hollow pipe, and the inside of each cylinder rod communicates with the discharge chamber of each hydraulic cylinder. An aerial work vehicle characterized in that one opening communicates with the pressure chamber, and the other opening inserts a tuning pipe extending to the connecting portion of the cylinder rod. 7. A pair of hydraulic cylinders constituting each hydraulic expansion / contraction mechanism, one of the hydraulic cylinders having a large diameter,
The other hydraulic cylinder was formed with a small diameter, and the cross-sectional area of the pressure chamber of the other hydraulic cylinder was made equal to the sum of the cross-sectional area of the discharge chamber of one hydraulic cylinder and the cross-sectional area of the inside of the cylinder rod and the outside of the pipe. An aerial work vehicle according to claim 6. 8. A hydraulic expansion / compression mechanism for one of the hydraulic expansion / contraction mechanisms is connected to the end of a tuning pipe on a large diameter hydraulic cylinder, and the other end of the synchronization pipe on a large diameter hydraulic cylinder for hydraulic expansion / contraction mechanism is connected. The cylinder rod in the large hydraulic cylinder in the mechanism is connected to the end of the tuning pipe in the small hydraulic cylinder in the other hydraulic expansion mechanism, and the cylinder in the large hydraulic cylinder in the other hydraulic expansion mechanism is connected. Connect the rod and the end of the tuning pipe in the small hydraulic cylinder in one hydraulic expansion mechanism, and connect the end of the tuning pipe in the small hydraulic cylinder in one hydraulic expansion mechanism to the cylinder rod in the small hydraulic cylinder in one hydraulic expansion mechanism and the small diameter in the other hydraulic expansion mechanism. The aerial work vehicle according to claim 6 or 7, wherein the hydraulic cylinder of (1) communicates with a cylinder rod. 9. A hydraulic pressure source is connected to the pressure chamber of a large diameter hydraulic cylinder in one hydraulic expansion mechanism, and
9. An aerial work vehicle according to claim 6, 7, or 8, wherein a hydraulic pressure generation source is connected to a discharge chamber of a small diameter hydraulic cylinder in the other hydraulic expansion / contraction mechanism.