JPH0645984U - Mast extension mechanism of vertical lift type aerial work vehicle - Google Patents

Abstract

(57) [Summary] [Purpose] When the hydraulic pressure of the cylinder was released for lowering the workbench, the mast member was controlled by wire tension to reduce the mast member fixed to the cylinder. (EN) A mast telescopic mechanism for a vertical lift type aerial work vehicle in which the wire does not sag and the mast member does not drop even when the mast is caught on the way. [Structure] A mast reduction wire 19 fixed to a third mast 13 is wound around a second sheave 20 provided below the second mast member 14 and fixed to a first mast member 15. Therefore, when the third mast member 13 is caught by the second mast member 14 and does not shrink, the second mast member 14 also does not shrink, so the third mast member 1
The wire 18 controlling the reduction speed of 3 does not sag. Accordingly, when the catching of the third mast member 13 is released, the third mast member 13 does not fall in a state where the falling speed of the third mast member 13 is not controlled.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an extension / contraction mechanism for a mast that raises and lowers a work platform provided in a vertically elevating work platform.

[0002]

[Prior art]

 Vertical lift type work platforms equipped with a work platform Vertically lift type work vehicle that uses a mast that is composed by nesting multiple mast members as a mechanism for raising and lowering the work platform. There is an aerial work vehicle. In this aerial work vehicle, a workbench is arranged on the outermost mast member, and a single-acting hydraulic cylinder that extends the cylinder rod when hydraulic pressure is supplied is provided inside the innermost mast member. ing. The extension of the mast extends the mast by the extension operation of the cylinder and the movement of the sheaves and wires arranged inside the plurality of mast members in order to obtain the amount of lifting of the work table beyond the stroke of the cylinder. The mechanism. Further, the mast is reduced by removing the hydraulic pressure of the cylinder so that the cylinder is reduced by the weight of the mast member other than the innermost part and the weight of the workbench.

A conventional vertical lifting type work platform equipped with a three-stage mast member will now be described with reference to FIG. In the vertically elevating work platform 2, a first mast member 25 having a hollow inside is fixedly installed on an upper part of a self-propelled chassis 21 and a hydraulic pressure is applied to the inside of the first mast member 25. A single-acting cylinder 26 is provided in which the cylinder rod 26a extends when the cylinder is open. The tip of the cylinder rod 26a is fixed to the inner surface of the top plate of the second mast member 24 that is telescopically attached to the first mast member 25. A sheave 27 is rotatably provided on an upper portion of an outer periphery of the second mast member 24, and a wire 28 having one end fixed to an upper portion of the first mast member 25 is wound around the sheave 27, and the other wire 28 is attached. The end is fixed to the third mast member 23.

In the vertical lift type work vehicle constructed as above, the workbench 22 is raised by supplying hydraulic pressure to the cylinder 26 and extending the cylinder rod 26a. When the cylinder rod 26a extends, the second mast member 24 fixed to the tip of the cylinder rod 26a extends, and the sheave 27 provided above the second mast member 24 also rises with respect to the first mast member member 25. To do. Since the wire 28, the other end of which is fixed to the third mast member 23, is wound around the sheave 27, the third mast member 23 is pulled up as the sheave 27 rises. Therefore, the workbench 22 arranged on the third mast member 23 can be lifted from the chassis 21 more than the stroke of the cylinder 26.

When the workbench 22 is lowered, the hydraulic pressure in the cylinder 26 is removed. When the hydraulic pressure in the cylinder 26 is released, the cylinder rod 26a contracts due to the weight of the second mast member 24 fixed to the tip of the cylinder rod 26a, and the second mast member 24 descends. At this time, the reduction speed of the second mast member 24 is controlled by controlling the speed at which the hydraulic pressure in the cylinder 26 is released. Then, the third mast member 23 is held by the tension caused by the weight of the work table 22 and the third mast member 23 of the wire 28 wound around the sheave 27, so that the third mast member 23 can freely fall. Instead, the second mast member 24 shrinks with the shrinking speed.

When the third mast member 23 is extended or contracted, the inner wall of the third mast member 23 slides on the outer wall of the second mast member 24, so that the inner wall of the lower end portion of the third mast member 23 and the second mast member 23 are slid. Sliders 23a, 24a are provided on the outer wall of the upper end of the toe member 24 to facilitate sliding of the third mast member 23 and the second mast member 24. Here, since there is a slight gap between the slider and the mast member due to the mechanism, when the third mast member 23 is largely tilted, the third mast member 23 is caught by the second mast member 24 and does not slide. There was an occasion. Therefore, in order to reduce the inclination of the third mast member 23, a large amount of lath La with the second mast member 24 when the third mast member 23 is extended is taken.

[0007]

[Problems to be solved by the device]

 However, since the workbench 22 is disposed on one side of the third mast member 23, the third mast member 23 tilts as shown in FIG. 3 depending on how the workbench 22 is loaded, and the slider 24a. In some cases, a catch may occur between the third mast member 23 and the slider 23a and the outer wall of the second mast member 24. In this state, when the hydraulic pressure in the cylinder 26 is released to lower the work table 22, the second mast member 24 is fixed to the cylinder rod 26a, so that the second mast member 24 is contracted by its own weight, but the third mast member 24 is reduced. The member 23 does not contract with respect to the second mast member 24, only the second mast member 24 with the sheave 27 being contracted, causing the wire 28 to loosen from the sheave 27. Then, when the catching of the third mast member 23 is eliminated in a state where the wire 28 is slack, the third mast member 23 is not held by the tension of the wire 28 until the wire 28 is hooked on the sheave 27 again. There is a problem that it may fall without controlling the reduction speed of 23.

The present invention has been made in view of the above problems, and reduces the mast member fixed to the cylinder when the hydraulic pressure of the single-acting cylinder is released to lower the workbench. Therefore, even if the mast member whose contraction speed is controlled by the tension of the wire is caught in the middle and does not contract, the vertical lifting type aerial work is constructed so that the wire does not sag and the mast member does not fall. It is intended to provide a mast expansion mechanism for a vehicle.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the mast expanding / contracting mechanism of the present invention is a vertical lifting mast composed of three mast members mounted in a telescopic manner, and is a first mast member fixed to a base. A cylinder rod is fixedly attached to the second mast member inside the single-acting cylinder. The first mast member and the third mast member are provided with two wires fixed to each other, and each wire is wound around two sheaves provided on an upper portion and a lower portion of the second mast member. The third mast member is expanded and contracted in line with the expansion and contraction of the second mast member.

[0010]

[Action]

 In the vertical lift type aerial work vehicle having the mast expansion / contraction mechanism as described above, when the third mast member is caught on the second mast member and does not shrink, the second mast member also does not shrink. 3 The wire that was controlling the reduction speed of the mast member does not sag. Therefore, when the hooking of the third mast member is released, the third mast member does not fall without controlling the reduction speed.

[0011]

【Example】

 Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. The vertically elevating work platform 1 is provided with a vertically movable mast including a first mast member 15, a second mast member 14, and a third mast member 13 on a chassis 11 that is self-propelled. Each mast member is telescopically and telescopically combined to form a vertical lifting mast, and a workbench 12 is provided on the third mast member 13. A first mast member 15 having a hollow inside is fixedly mounted on an upper portion of the chassis 11, and a single-acting cylinder 16 in which a cylinder rod 16a extends when hydraulic pressure is applied to the inside of the first mast member 15. Is provided. Then, the second mast member 14 is attached to the outer periphery of the first mast member 15 in a nested manner, and the tip of the cylinder rod 16a penetrating the top plate of the first mast member 15 is brought into contact with the inner surface of the top plate of the second mast member 14. It is fixed.

The third mast member 13 is also telescopically attached to the outer periphery of the second mast member 14, and one end of the mast extending wire 18 is fixed to the inner wall of the third mast member 13. The mast extension wire 18 is wound around the first sheave 17 provided on the upper portion of the second mast member 14, passes through the inside of the second mast member 14, and the other end is fixed to the upper portion of the first mast member 15. ing. Further, one end of the mast reducing wire 19 is fixed to the inner wall of the third mast member 13, and the mast reducing wire 19 is wound around the second sheave 20 provided under the second mast member 14, The other end passes through the space between the second mast member 14 and the first mast member 15 and is fixed to the upper portion of the first mast member 15.

In the vertical lift type work platform constructed as described above, the workbench 12 is raised by supplying hydraulic pressure to the cylinder 16 and extending the cylinder rod 16a. When the cylinder rod 16a extends, the second mast member 14 fixed to the tip end of the cylinder rod 16a extends, and the first sheave 17 provided on the upper portion of the second mast member 14 also moves with respect to the first mast member 15. To rise. Since the mast extension wire 18 having the other end fixed to the third mast member 13 is wound around the first sheave 17, the third mast member 13 is pulled up by raising the first sheave 17. Therefore, the workbench 12 arranged on the third mast member 13 can be lifted from the chassis 11 more than the stroke of the cylinder 16.

When lowering the workbench 12, the hydraulic pressure of the cylinder 16 is removed. When the hydraulic pressure in the cylinder 16 is released, the weight of the second mast member 14 fixed to the tip of the cylinder rod 16a causes the cylinder rod 16a to contract and the second mast member 14 to descend. At this time, the reduction speed of the second mast member 14 is controlled by controlling the speed at which the hydraulic pressure of the cylinder 16 is released. The third mast member 13 is held by the tension caused by the weight of the work table 12 and the third mast member 13 of the mast extension wire 18 wound around the first sheave 17, It contracts as the second mast member 14 contracts.

When the third mast member 13 is expanded or contracted, the inner wall of the third mast member 13 slides on the outer wall of the second mast member 14, so that the inner wall of the lower end portion of the third mast member 13 and the second mass member 13 are slid. Sliders 13a and 14a are provided on the outer wall of the upper end of the toe member 14 to facilitate sliding of the third mast member 13 and the second mast member 14. Here, since a slight gap is generated between the slider and the mast member due to the mechanism, when the third mast member 13 tilts largely, the third mast member 13 is not caught by the second mast member 14 and does not shrink. was there.

However, even when the third mast member 13 does not shrink, the second mast member 14 tries to shrink due to its own weight because the hydraulic pressure in the cylinder 16 is released. However, unless the third mast member 13 is contracted, the second mast member 14 is not contracted by the tension of the mast contracting wire 19 wound around the second sheave 20 provided at the lower portion of the second mast member 14. . Therefore, since only the second mast member 14 does not contract with respect to the first mast member 15, the slack in the mast extension wire 18 that controls the contraction speed of the third mast member does not occur. Therefore, when the hooking of the third mast member 13 to the second mast member 14 is eliminated, the third mast member 13 on which the workbench 12 is arranged is irrespective of the controlled reduction speed, There is no free fall of 18 slacks.

[0017]

[Effect of device]

 As described above, in the mast telescopic mechanism of the vertical lift type aerial work vehicle according to the present invention, the mast contraction wire fixed to the third mast is provided with the second sheave provided under the second mast member. And is fixed to the first mast member. For this reason, when the third mast member is caught by the second mast member and is not reduced, the second mast member is not reduced either, so that the wire that has controlled the reduction speed of the third mast member does not slack. This prevents the third mast member from falling in a state where the falling speed of the third mast member is not controlled when the hooking of the third mast member is released. Further, even if the third mast member is caught, the problem of dropping the mast member does not occur, so that it is possible to reduce the amount of the mast straps of the second mast member and the third mast member. In addition, the mast telescopic mechanism of the vertical lift type aerial work vehicle according to the present invention is the same as the mast telescopic mechanism of the conventional vertical lift type aerial work vehicle equipped with a single-acting cylinder, and a wire and sheave for reducing the mast are added. Since it is only done, it can be manufactured at low cost. Also, even if the workbench is caught by another structure, the reduction of the cylinder due to its own weight only stops, so there is no load on the wire, so there is no wire breakage.

[Brief description of drawings]

FIG. 1 is a side view of a vertically elevating work platform equipped with a mast retracting mechanism according to the present invention.

FIG. 2 is a side view of a vertical lifting type work platform equipped with a conventional mast expansion mechanism.

FIG. 3 is a side view of a conventional mast expansion / contraction mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical lifting type work platform 11 Chassis 12 Work table 13 Third mast member 14 Second mast member 15 First mast member 16 Single-acting cylinder 17 First sheave 18 Mast extension wire 19 Mast reduction wire 20 Second Sheave

Claims (1)

[Scope of utility model registration request] 1. A first mast member attached to a base, and a second mast member telescopically attached to the outer periphery of the first mast member so as to extend and contract toward the upper end direction of the first mast member, A third mast member telescopically attached to the outer periphery of the second mast member toward the upper end of the second mast member, and the second mast member provided in the first mast member to expand and contract. Single-acting cylinder, first sheave provided on the upper part of the second mast member, second sheave provided on the lower part of the second mast member, and the first sheave fixed to the first mast member. A mast extension wire wound around the third mast member and fixed to the third mast member; and a mast contraction wire fixed to the first mast member and wound around the second sheave and fixed to the third mast member. Vertical elevating aerial mast telescoping mechanism, characterized in that to become to.