JP2002037586A - Device for holding above-ground height of crane hook - Google Patents

Abstract

PROBLEM TO BE SOLVED: To offer a simple construction of holding the above-ground height of a hook almost constant by interlocking a derricking cylinder with a winch hydraulic motor during boom derricking motion. SOLUTION: A crane having the boom for performing derricking motion with a boom derricking hydraulic cylinder 9 and the winch for hoisting/lowering the hook with the winch hydraulic motor 10, comprises a rise-lowering interlocking pipe line 32 for interlocking a rise pipe line 34 for the boom derricking hydraulic cylinder 9 with a lowering pipe line 28 for the winch hydraulic motor 10 via an interlocking change valve 30 and a fall-hoisting interlocking pipe line 31 for interlocking a fall pipe line 27 for the boom derricking hydraulic cylinder 9 with a hoisting pipe line 29 for the winch hydraulic motor 10 via the interlocking change valve 30, either the rise-lowering interlocking pipe line 32 or the fall-hoisting interlocking pipe line 31 having a distribution flow combining valve 40 for distribution and combination in such a manner that the rate of a flow rate on the side of the boom derricking hydraulic cylinder 9 to a flow rate on the side of the winch hydraulic motor 10 is as predetermined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crane hook height holding device for holding a hook height substantially constant when raising and lowering a crane boom.

[0002]

2. Description of the Related Art In a conventional crane, a winch is provided on a column for pivotally supporting the boom so that the boom can be raised and lowered, and a wire rope which is fed from the winch and fed is guided to a boom distal end through a pulley at the boom distal end. The hook is suspended from the end of the boom by hanging the hook.

[0003] Accordingly, the height of the hook suspended from the boom tip varies with the elevation of the boom. That is, when the boom is raised, the ground height of the hook increases, and when the boom is turned down, the ground height of the hook decreases. When raising and lowering the boom during crane operation, in order to keep the ground height of the hook constant, the crane operator performs the winch lowering operation at the same time as the boom raising operation, and the winch lowering operation at the same time as the boom lowering operation. It is necessary to perform a hoisting operation, but at this time, since the two operating levers must be operated at the same time, the operation is complicated and requires skill, and other operations (boom expansion and contraction, turning, etc.) are also performed. Was extremely difficult to do.

In view of the above, a flow dividing valve device is provided in each of a starting line of a hydraulic cylinder for raising and lowering a boom and a middle portion of a lower line of the hydraulic cylinder. The diversion valve device connected to the lower pipeline and provided on the lower pipeline of the hydraulic cylinder for raising and lowering the boom is connected to the lifting pipeline of the hydraulic motor for winch. There is a configuration in which the lower and upper windings are linked to maintain the height of the hook above the ground constant (see Japanese Patent Publication No. 57-29394).

In this crane hook height maintaining device, the control device considers the boom up / down amount, the correction value based on the boom angle, the hook movement amount, and the like based on information from a detector that detects the boom up / down angle. By controlling the diverting ratio of the diverting valve device, the height of the hook above the ground is maintained substantially constant when the boom is raised and lowered.

[0006]

However, in order to maintain the hook ground height constant irrespective of the boom undulation, the hook ground height holding device of this crane requires a vertical movement amount of the hook by raising and lowering the boom. Must be constantly changed, so that a plurality of shunt valve devices, a detector for detecting the elevation angle of the boom, a control device for controlling the shunt valve device based on information from the detector, and the like are required, and the structure is complicated and cost is low. Will also be higher.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem in a crane hook height maintaining device. When the boom is raised and lowered, the hoist cylinder and the winch hydraulic motor are linked to each other to make the hook ground height higher. It is an object of the present invention to provide a low-cost hook ground-height holding device having a simple structure and capable of holding the hook substantially constant.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a crane hook height maintaining apparatus comprising: a boom for raising and lowering by a hydraulic cylinder for raising and lowering a boom; and a winch for raising and lowering the hook by a hydraulic motor for winch. A crane provided with a boom hoist hydraulic cylinder and a winch hydraulic motor, and a hoist hydraulic motor. A winding-up interlocking line for communicating the winding-up line with the hoisting line of the winch hydraulic motor through an interlocking switching valve is provided, and either the winding-down interlocking line or the winding-up interlocking line is provided. On the other hand, the above-mentioned problem is solved by providing a distribution / collection valve which distributes and collects the flow rate of the hydraulic cylinder for the boom hoist and the flow rate of the hydraulic motor for the winch at a predetermined ratio.

In the hook ground height holding device of the present invention, when the boom is raised and lowered while the hook ground height is kept constant during the crane operation, the interlocking switching valve is switched to the interlocking side. Then, the starting line of the hydraulic cylinder for raising / lowering the boom and the lowering line of the hydraulic motor for the winch communicate with the lowering interlocking line, and the lowering line of the hydraulic cylinder for raising / lowering the boom and the hydraulic motor for the winch are hoisted. The pipeline communicates with the upwinding interlocking pipeline, and the hydraulic cylinder for boom hoisting and the hydraulic motor for winch are connected in parallel, and the operator operates either the boom hoisting switching valve or the winch switching valve. By doing so, the hydraulic cylinder for raising and lowering the boom and the hydraulic motor for winch are linked.

At this time, the flow rate on the hydraulic cylinder side for raising and lowering the boom and the flow rate on the hydraulic motor side for winch are distributed and collected by the distribution collecting valve at a ratio set so that the height above the hook is constant. Therefore, when the boom stands, the winch wire rope is extended in synchronization with the boom, and the ground height of the hook is kept constant.When the boom is lowered, the winch wire rope is extended in synchronization with the boom. The hook ground height is kept almost constant.

When the interlocking switching valve is not switched to the interlocking side, the hydraulic cylinder for raising and lowering the boom and the hydraulic motor for winch operate independently of each other as in the conventional case. This crane hook height maintaining device can be configured simply by adding an interlocking switching valve and distribution / collection valve in the hydraulic circuit, and does not require a boom angle detector or control device. Is simple and low cost.

[0012]

FIG. 1 is a front view of a crane provided with a hook ground height holding device according to an embodiment of the present invention.
FIG. 2 is a hydraulic circuit diagram of the crane hook height maintaining device. As shown in FIG. 1, the crane 1 is provided with a column 6 which is turned by a turning hydraulic motor 5 on a base 4 which is supported by an outrigger 2 having left and right outrigger hydraulic cylinders 3L, 3R. The base end of the boom 7 is pivotally supported at a pivot point O at the upper end of the column 6. The boom 7 is extended and retracted by a hydraulic cylinder 8 for extending and retracting the boom, and is raised and lowered by a hydraulic cylinder 9 for raising and lowering the boom.

The column 6 is provided with a winch 11 which is operated by a winch hydraulic motor 10 for hoisting and lowering. The wire rope 12 which is fed out from the winch and fed in is guided to the tip of the boom 7. The hook 13 is hung from the tip of the boom 7 by being hooked on the hook 13 via a pulley (not shown) pivotally supported by a sheave pin P at the tip of the boom 7.

The ground height H of the hook is expressed by the following equation. H = h + L sin θ−1 (1) h: Height of pivot point O L: Distance between pivot point O and sheave pin P θ: Boom undulation angle l: Hook hanging length Here, boom 7 expands and contracts If not, h and L are constants. Accordingly, if the hoisting / unwinding operation is not performed and l is constant, the hook ground height H changes as the boom 7 rises and falls. That is, when the boom 7 is raised, the hook ground height H
Is raised, and if the boom 7 is turned down, the hook ground height H
Becomes lower.

In this crane 1, as shown in FIG.
Boom hoist hydraulic cylinder 9 is boom hoist switching valve 1
5. The winch hydraulic motor 10 is the winch switching valve 1.
6. The boom extending and retracting hydraulic cylinder 8 is a boom extending and retracting switching valve 17, the turning hydraulic motor 5 is a turning switching valve 18, and the outrigger hydraulic cylinders 3L and 3R are outrigger switching valves 19.
L, 19R, the discharge line 22 of the hydraulic pump 21
And a return line 24 to the tank 23.

These switching valves 15, 16, 17, 18,
Reference numerals 19L and 19R denote three-position manually operated switching valves, which are manually operated by an operator to provide a hydraulic cylinder 9 for raising and lowering a boom, a hydraulic motor 10 for a winch, a hydraulic cylinder 8 for extending and retracting a boom, and a hydraulic motor for turning. 5 and the left and right hydraulic cylinders for outriggers 3L, 3R can be operated. In the neutral position, the discharge line 22 returns to the return line 24.
To communicate with A relief valve 25 is provided between the discharge pipe 22 and the return pipe 24.

Further, between the starting line 34 of the hydraulic cylinder 9 for raising and lowering the boom and the lowering line 28 of the hydraulic motor 10 for the winch, an interlocking switching pipe which is communicated by switching an interlocking switching valve 30 is provided. A path 32 is connected, and a head winding which is communicated between the winding pipe 27 of the hydraulic cylinder 9 for raising and lowering the boom and the hoisting pipe 29 of the hydraulic motor 10 for winch by switching the switching valve 30 for interlocking. The upper interlocking conduit 31 is connected.

The flow rate of the hydraulic cylinder 9 for raising and lowering the boom toward the starting pipe 34 and the flow rate of the hydraulic motor 10 for winch toward the lowering pipe 28 have a predetermined ratio. A distribution / collection valve 40 for performing distribution / collection is provided.
The distribution collecting valve 40 is set so as to distribute and collect the flow rate on the hydraulic cylinder 9 for boom undulation and the flow rate on the hydraulic motor 10 for the winch in such a ratio that the height above the hook is constant. .

When raising and lowering the boom 7 while maintaining the hook ground height H constant during crane operation, first, the interlocking switching valve 30 is switched to the interlocking side. Then, the starting line 34 of the boom raising / lowering hydraulic cylinder 9 and the lowering line 28 of the winch hydraulic motor 10 communicate with the lowering interlocking line 32, and the lowering line 27 of the boom raising hydraulic cylinder 9 communicates with the lower line 27. Since the hoisting hydraulic line 9 of the winch hydraulic motor 10 communicates with the hoisting hoisting interlocking conduit 31, the boom hoist hydraulic cylinder 9 and the winch hydraulic motor 10 are connected in parallel, and the boom hoist switching valve is provided. 15 operations are linked.

That is, the operator operates the boom-up / down switching valve 1
5 is switched to the starting side, the discharge line 22 of the hydraulic pump 21
Is supplied from the starting line 34 to the interlocking switching valve 3.
0, enters the distribution collecting valve 40, where it is diverted, one of which enters the boom-raising hydraulic cylinder 9 of the boom-raising hydraulic cylinder 9 to extend the boom-raising hydraulic cylinder 9, and the other is the winch hydraulic motor. Then, the hydraulic motor 10 for winch is moved into the lower winding line 28 of 10 to perform the lowering operation.

The lower oil chamber 2 of the hydraulic cylinder 9 for raising and lowering the boom.
The return oil from 6 is the lower pipe line 27 and the boom directional switching valve 1
5. Return to the tank 23 via the return line 24. The return oil from the winch hydraulic motor 10 passes from the hoisting line 29 of the winch hydraulic motor 10 to the winding-up interlocking line 31 and the interlocking switching valve 30, and then to the lowering line 27 and the boom up / down switching. It returns to the tank 23 via the valve 15 and the return line 24.

At this time, the flow rate on the hydraulic cylinder 9 side for raising and lowering the boom and the flow rate on the hydraulic motor 10 side for the winch always have a predetermined ratio by the distribution / collection valve 40 regardless of the pressure difference between the respective circuits. Be distributed. Therefore, when the boom 7 stands up, the wire rope 12 of the winch 11 is paid out in synchronization with the boom 7 and the hook ground height H is kept substantially constant.

When the operator switches the boom-up / down switching valve 15 to the lower side, the pressure oil supplied from the discharge line 22 of the hydraulic pump 21 is partially moved from the reduced line 27 to the boom-up / down hydraulic cylinder 9. After entering the side oil chamber 26, the hydraulic cylinder 9 for raising and lowering the boom is reduced.
The winch hydraulic motor 10 enters the hoisting hydraulic line 10 via the winding-up interlocking hydraulic line 31 to perform the hoisting operation of the winch hydraulic motor 10.

The oil chamber 3 on the raising side of the hydraulic cylinder 9 for raising and lowering the boom.
3 and the return oil from the winch hydraulic motor 10 are collected by the distribution / collection valve 40, and the interlocking switching valve 30, the starting line 34, the boom raising / lowering switching valve 15, the return line 24 are provided. And returns to the tank 23. At this time, the flow rate on the boom hoist hydraulic cylinder 9 side and the winch hydraulic motor 10
The flow rate on the side is always collected by the distribution / collection valve 40 so as to have a predetermined ratio regardless of the pressure difference between the respective circuits. Therefore, when the boom 7 falls down, the wire rope 12 of the winch 11 is retracted in synchronism with the boom 7, and the ground height H of the hook is kept substantially constant.

When the winch switching valve 16 is operated to the winding upper side while the interlocking switching valve 30 is switched to the interlocking side, the hoisting line 29 of the winch hydraulic motor 10 is connected via the interlocking switching valve 30. Lower pipeline 27 of hydraulic cylinder 9 for raising and lowering boom
However, since the starting line 34 is blocked by the interlocking switching valve 30, the hydraulic cylinder 9 for raising and lowering the boom is not lowered, and only the lifting operation of the hydraulic motor 10 for winch is performed. Will be

The interlocking switching valve 30 may be a manual switching valve or an electromagnetic switching valve. In addition, an electrical or mechanical switching interlocking mechanism may be provided so that the interlocking switching valve 30 switches at the same time as the operation of the boom-raising / lowering switching valve 15. In a normal state in which the interlocking switching valve 30 is not switched, the boom-up / down hydraulic cylinder 9 and the winch hydraulic motor 10 are independently operated by the boom-up / down switching valve 15 and the winch switching valve 16, respectively. .

In the normal state, the hoisting and lowering operation of the winch switching valve 16 and the boom raising / lowering switching valve 15 are performed.
Or, with the interlocking switching valve 30 switched to the interlocking side,
At the time of the hoisting and lowering operation of the winch switching valve 16, oil tries to flow in the collecting direction on one side of the distribution collecting valve 40.
Since there is no oil flow in the collecting direction on the other side, the oil is blocked and does not flow through the distribution collecting valve 40.

FIG. 3 shows an example in which an interlocking switching valve 50 having a different circuit configuration is used in the hydraulic circuit of FIG. The interlocking switching valve 50 has more cylinder ports than the interlocking switching valve 30 of FIG. 2, and the reduced pipeline 27 of the boom-raising hydraulic cylinder 9 is connected to the reduction-side oil chamber 26 via the interlocking switching valve 50. I have. The rest is the same as the hydraulic circuit of FIG. 2, and the operation is substantially the same.

FIG. 4 shows another embodiment, that is, in the hydraulic circuit of FIG.
The example shown in FIG. In this example, the interlocking switching valve 3
When the switching valve 15 is switched to the interlocking side and the switching valve 15 for boom raising and lowering is switched to the lowering side, the hydraulic oil supplied from the discharge line 22 of the hydraulic pump 21 is collected from the lowering line 27 via the interlocking switching valve 30. It enters the flow valve 40 and is diverted there, one of which enters the lower oil chamber 26 of the hydraulic cylinder 9 for raising and lowering the boom to reduce the hydraulic cylinder 9 for raising and lowering the boom, and the other is the hoisting pipe of the hydraulic motor 10 for winch. In the path 29, the winch hydraulic motor 10 is hoisted.

The return oil from the extension-side oil chamber 33 of the hydraulic cylinder 9 for raising and lowering the boom and the return oil from the hydraulic motor 10 for winch pass through the extension pipe 34, the boom-lowering switching valve 15, and the return pipe 24. Return to the tank 23. When the boom hoisting switching valve 15 is switched to the raising side, part of the pressure oil supplied from the discharge line 22 of the hydraulic pump 21 is transferred from the raising line 34 to the raising side oil chamber 33 of the boom hoisting hydraulic cylinder 9. The hydraulic cylinder 9 for elevating and lowering the boom is extended, and the others enter the lowering line 28 of the hydraulic motor 10 for winch via the interlocking switching valve 30 and the interlocking lowering line 32, and the winch hydraulic motor 1
The lowering operation of 0 is performed.

The lower oil chamber 2 of the hydraulic cylinder 9 for raising and lowering the boom.
6 and the return oil from the winch hydraulic motor 10 are collected by the distribution collecting valve 40, and the interlocking switching valve 30, the shallow conduit 27, the boom extension / retract switching valve 17, and the return conduit 24 are collected. And returns to the tank 23. Since the distribution and collection valve 40 always distributes and collects the water at a predetermined ratio, the height H above the hook is kept constant when the boom 7 is raised and lowered, as in the case of FIG.

FIG. 5 shows an example in which an interlocking switching valve 51 having a different circuit configuration is used in the hydraulic circuit of FIG. This interlocking switching valve 51 has more cylinder ports than the interlocking switching valve 30 of FIG. 4, and the starting line 34 of the hydraulic cylinder 9 for raising and lowering the boom is connected to the starting oil chamber 33 via the interlocking switching valve 51. I have. The rest is the same as the hydraulic circuit of FIG. 4, and the operation is substantially the same.

FIG. 6 shows another embodiment, that is, in the hydraulic circuit of FIG. 2, when the winch switching valve 16 is switched, the boom-lift hydraulic cylinder 9 and the winch hydraulic motor 10 are operated.
In this example, the interlocking switching valve 30 is provided on the winch switching valve 16 side so that the hook height H when the boom 7 is raised and lowered can be kept constant. In this example, when the operator switches the interlocking switching valve 30 to the interlocking side and switches the winch switching valve 16 to the lowering side, the pressure oil supplied from the discharge pipeline 22 of the hydraulic pump 21 is reduced by the lowering pipeline. From 28, it enters the distribution / collection valve 40 via the interlocking switching valve 30, where it is diverted, one of which enters the starting oil chamber 33 of the boom raising / lowering hydraulic cylinder 9 to extend the boom raising / lowering hydraulic cylinder 9, The other is the lower winding line 2 of the winch hydraulic motor 10.
8 and the lowering operation of the winch hydraulic motor 10 is performed.

The lower oil chamber 2 of the hydraulic cylinder 9 for raising and lowering the boom.
The return oil from 6 is connected to the lower pipe 27, the upper winding interlocking pipe 31, the interlocking switching valve 30, the winch switching valve 16, the return pipe 24.
And returns to the tank 23. The return oil from the winch hydraulic motor 10 returns from the hoisting line 29 of the winch hydraulic motor 10 to the tank 23 via the winch switching valve 16 and the return line 24.

When the operator switches the winch switching valve 16 to the upper side of the winding, part of the pressure oil supplied from the discharge pipe 22 of the hydraulic pump 21 is transferred from the interlocking switching valve 30 to the lower pipe 2.
7, the lower oil chamber 26 of the hydraulic cylinder 9 for raising and lowering the boom.
Then, the hydraulic cylinder 9 for raising and lowering the boom is reduced, and the others enter the hoisting line 29 of the hydraulic motor 10 for winch, and the lifting operation of the hydraulic motor 10 for winch is performed.

The oil chamber 3 on the raising side of the hydraulic cylinder 9 for raising and lowering the boom.
3 and the return oil from the winch hydraulic motor 10 are collected by the distribution / collection valve 40, and the interlocking switching valve 30, the lowering line 28, the winch switching valve 16, the return line 24 are collected. And returns to the tank 23. The flow rate on the hydraulic cylinder 9 side for boom raising and lowering and the flow rate on the hydraulic motor 10 for winch side are distributed and collected by the distribution and collection valve 40 so as to always have a predetermined ratio. Therefore, when the boom 7 is raised and lowered, the hook ground height H is kept constant.

FIG. 7 shows an example in which an interlocking switching valve 50 having the same circuit configuration as that of FIG. 3 is used in the hydraulic circuit of FIG. This interlocking switching valve 50 is the interlocking switching valve 3 of FIG.
There are more cylinder ports than 0, and the hoisting line 29 of the winch motor 10 is connected to the winch motor 10 via the interlocking switching valve 50. The rest is the same as the hydraulic circuit of FIG. 6, and the operation is substantially the same.

FIG. 8 shows another embodiment, that is, an example in which the distribution / collection valve 40 is provided in the upper winding interlocking conduit 31 in the hydraulic circuit of FIG. In this example, the interlocking switching valve 30
Is switched to the interlocking side, and the winch switching valve 16 is switched to the winding side, the pressure oil supplied from the discharge line 22 of the hydraulic pump 21 is distributed and collected from the winding line 29 via the interlocking switching valve 30. It enters the valve 40 and is diverted there, one of which enters the lower side oil chamber 26 of the hydraulic cylinder 9 for raising and lowering the boom and contracts the hydraulic cylinder 9 for raising and lowering the other. At step 29, the winch hydraulic motor 10 is hoisted.

The oil chamber 3 on the raising side of the hydraulic cylinder 9 for raising and lowering the boom.
The return oil from 3 is connected to the interlocking switching valve 30, the lower winding line 28,
Winch switching valve 16, tank 23 via return line 24
Return to The return oil from the winch hydraulic motor 10 returns to the tank 23 via the lowering line 28, the winch switching valve 16, and the return line 24. When the winch switching valve 16 is switched to the lowering side, the pressure oil supplied from the discharge line 22 of the hydraulic pump 21 partially flows from the lowering line 28 to the interlocking switching valve 3.
0, the hydraulic cylinder 9 for extending the boom is extended by entering the oil chamber 33 of the hydraulic cylinder 9 for raising and lowering the boom via the interlocking conduit 32 for raising and lowering the boom, and the other is connected to the lowering line 28 of the hydraulic motor 10 for the winch. Then, the lowering operation of the winch hydraulic motor 10 is performed.

The lower oil chamber 2 of the hydraulic cylinder 8 for raising and lowering the boom.
6 and the return oil from the winch hydraulic motor 10 are collected by the distribution / collection valve 40, and the interlocking switching valve 30, the hoisting line 29, the winch switching valve 16, the return line 24 are collected. And returns to the tank 23. Since the distribution / collection valve 40 always distributes and collects the water at a predetermined ratio, the height H above the hook is kept constant when the boom 7 is raised and lowered, as in FIG.

FIG. 9 shows an example in which an interlocking switching valve 51 having the same circuit configuration as that of FIG. 5 is used in the hydraulic circuit of FIG. This interlocking switching valve 51 is the interlocking switching valve 3 of FIG.
Hydraulic motor for winch 1 with more cylinder ports than 0
The 0 lower winding line 28 is connected to the winch hydraulic motor 10 via the interlocking switching valve 51. The rest is the same as the hydraulic circuit of FIG. 8, and the operation is substantially the same.

Table 1 shows the relationship between the functions of the switching valve operated during the interlocking operation, the distribution / collection valve, and the interlocking switching valve in the embodiment shown in FIGS.

[0043]

[Table 1]

By the way, in the hook ground height holding device of the present invention, the hydraulic cylinder 9 for raising and lowering the boom and the hydraulic motor 10 for winch are connected in parallel, and the distribution / collection valve 40 controls the flow rate on the hydraulic cylinder 9 for raising and lowering the boom. And the flow rate on the winch hydraulic motor 10 side are distributed and collected at a predetermined ratio, and the expansion and contraction of the hydraulic cylinder 9 for boom raising and lowering and the hydraulic motor 1 for winch are performed.
The hook height H is made substantially constant by interlocking with the zero lower winding operation and correcting the hook suspension length l.

Here, since the amount of expansion and contraction of the hydraulic cylinder 9 for raising and lowering the boom and the amount of extension of the wire rope 12 are proportional, the amount of expansion and contraction of the hydraulic cylinder 9 for raising and lowering the boom and the amount of change in the hook suspension length 1 are determined. Is proportional. On the other hand, the amount of expansion and contraction of the hydraulic cylinder 9 for raising and lowering the boom and the sheave pin P of the boom 7
The amount of change in the height of the hook is not strictly proportional. However, even if the height H of the hook is intended to be kept constant when the boom 7 is raised and lowered, if the height of the hook is not completely constant, it is not used. It is not impossible to do so, and if the ground height H of the hook can be kept substantially constant, there is no problem.

Since the amount of expansion and contraction of the hydraulic cylinder 9 for raising and lowering the boom and the amount of change in the height of the sheave pin P of the boom 7 can be considered to be approximately proportional within the range used during normal work, the winch operation during the operation of raising and lowering the boom is performed. It can be omitted. When the boom 7 is extendable and contractable, the length of the boom 7 changes, thereby changing the hook suspension length 1 to be corrected. Therefore, it is desirable to set the distribution / collection ratio of the distribution / collection valve 40 so that the ground height H of the hook can be kept constant based on the length of the boom 7 that is used most frequently during operation.

[0047]

As described above, the crane hook ground height holding device of the present invention is capable of maintaining the hook ground height substantially constant by interlocking the boom hoist hydraulic cylinder and the winch hydraulic motor. Since it is possible, operability is improved. Further, the configuration is simple and the cost is low.

[Brief description of the drawings]

FIG. 1 is a front view of a crane provided with a hook ground height holding device according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

FIG. 3 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

FIG. 4 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

FIG. 5 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

FIG. 6 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

FIG. 7 is a hydraulic circuit diagram of a crane hook height maintaining device.

FIG. 8 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

FIG. 9 is a hydraulic circuit diagram of the hook ground height holding device of the crane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crane 2 Outrigger 4 Base 6 Column 7 Boom 9 Hydraulic cylinder for raising and lowering boom 10 Hydraulic motor for winch 11 Winch 12 Wire rope 13 Hook 15 Switching valve for raising and lowering boom 16 Switching valve for winch 21 Hydraulic pump 22 Discharge pipeline 23 Tank 24 Return Pipe 26 Lower oil chamber 27 Lower pipe 28 Lower pipe 29 Lower pipe 30 Interlocking switching valve 31 Lower coil interlocking pipe 32 Starting lower interlocking pipe 33 Starting oil chamber 34 Starting pipe 40 Distribution / collection valve 50 Interlocking switching valve 51 Interlocking switching valve

Claims (1)

[Claims] 1. A crane provided with a boom that raises and lowers an operation by a hydraulic cylinder for raising and lowering a boom and a winch that performs a hoisting and lowering operation of a hook by a hydraulic motor for a winch. Link between the hoisting down link of the hydraulic cylinder for raising and lowering the boom and the hoisting line of the hydraulic motor for the winch. A winding-up interlocking line which is communicated via a switching valve is provided, and the flow rate of the hydraulic cylinder for the boom hoisting and the hydraulic motor for the winch are provided to either the winding-down interlocking line or the winding-up interlocking line. A distribution collecting valve for distributing and collecting the flow so that the flow rate of the crane becomes a predetermined ratio.