JP2597503B2 - Crane cylinder control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is capable of moving up and down a kelly bar, a vibratory pile driver and the like of an earth drill disclosed in Japanese Utility Model Publication No. 47-30721 and Japanese Utility Model Publication No. 62-23904. The present invention relates to a control device for a simple crane cylinder.

[Conventional technology]

Such a winding drum control device generally inserts a counterbalance valve into a high pressure side oil passage at the time of winding between a winch motor and a center bypass type directional control valve. When free descent is enabled, as shown in Japanese Utility Model Publication No. 51-48142,
A clutch and a brake control valve device capable of cutting a clutch provided between a bobbin shaft and a bobbin and releasing a bobbin brake, and exporting to a country where free fall of the kelly bar or the like is not permitted. In the case of the control device, at least the clutch was not provided. In addition, it is a real body 58-1182
As shown in Japanese Patent Publication No. 8 and the like, it is normal to attach a turbulence prevention device that constantly presses and presses a rope pushing roller to the outside of the winding rope of the winding drum. Has to always apply a tension exceeding a certain limit by means of a suspended heavy object or the like.

[Problems to be solved by the invention]

When a kelly bar of an earth drill is hung on a bobbin rope extended from the bobbin and drilled with a drilling tool such as a drilling bucket attached to the lower end of the kelly bar, first, a direction switching valve is operated by a winch operating lever. The drilling tool is grounded by controlling the lowering of the bobbin. However, since the kelly bar is vertically guided by the rotary table for driving, the bobbin is erroneously moved from the bobbin. If the rope is pulled out too much, there is a risk that the bobbin rope between the bobbin and the pulley at the end of the boom will be loosened by its own weight, and the winding rope of the bobbin will bulge out due to its own elasticity, forming a turbulent shape.

If the wrapped rope becomes irregularly wound, it may be necessary to drive the kelly bar with a rotary table to rotate the drill, or to lift the kelly bar to discharge the excavated soil in the drilling bucket after drilling. When a large tension is applied, the winding ropes of the winding drum are strongly rubbed against each other, and the ropes are quickly damaged.Therefore, a worker is required on the winding drum side to inform a crane operator of the condition of the winding rope. It must be arranged to prevent the wrapping rope from becoming irregularly wound.

A winch operating lever is also provided so that the drilling tool (piercing bucket) can be lowered while drilling, in which the rotary table driving of the kelly bar and the pressing of the rotary table by the thrust cylinder must be controlled simultaneously. Alternatively, the brake release operation lever (pedal) must be continuously operated, and the switching between the drilling operation and the excavating operation of the excavated soil is complicated. Therefore, a decrease in the drilling efficiency by an unskilled crane operator cannot be avoided. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to automatically prevent the bobbin winding from being caused by the loosening of the bobbin rope at the time of the descent of the drilling tool at the lower end of the kelly bar and the pile of the vibratory piling machine. A second object of the present invention is to prevent complicated control of an earth drill or a vibratory pile driver by providing this turbulence prevention device, and to prevent a decrease in drilling efficiency by an unskilled crane operator. is there.

[Means for solving the problem]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a crane winding drum having a counterbalance valve (3) inserted into a high pressure side oil passage at the time of hoisting between a winch motor (1) and a center bypass type directional control valve (2). In the control device, between the high pressure side oil passage and the low pressure side oil passage at the time of hoisting between the winch motor and the counter balance valve, the flow from the high pressure side oil passage to the low pressure side oil passage can be prevented. Serially connecting a pilot check valve (4) and a relief valve (5) which is opened by the pilot oil pressure when the hydraulic pressure on the primary side of the pilot check valve reaches a pressure capable of preventing winding of the bobbin rope;
A position for supplying a hydraulic pressure having a pressure equal to or higher than a pilot set pressure of the relief valve (5) to the high-pressure side oil passage via a check valve (6); a primary side of the check valve (6); A switching valve (8) having a position for connecting a pilot oil passage (7) provided between the check valve and the check valve (4) to a tank.
The pilot set pressure of the pilot check valve and the check valve is set lower than the pilot set pressure of the relief valve (5).

Also, a device for generating a pilot hydraulic pressure or a signal is mounted on the output side of the winch motor control direction switching valve (2) or its operating mechanism only while the winch motor is switched to the hoisting or lowering motor driving position. Alternatively, in response to a signal, the switching valve (8) is connected to the tank so that the pilot oil passage (7) provided between the primary side of the check valve (6) and the pilot check valve (4) is connected to the tank. May be provided in the switching valve.

In addition, a control device for the crane winding drum is connected to the output shaft of one winch motor (1).
Clutch cylinders (13), (14) which can be connected to the respective drive shafts (11), (12) of (10) and the clutches provided between the respective drive shafts and the corresponding winding cylinders by constantly cutting and energizing them. ), Brake cylinders (15), (16) provided on the main and sub-winding cylinders, respectively, which can release brakes that are constantly applied, and clutch cylinders and brake cylinders of the main and sub-winding cylinders, respectively, in tanks. A main / sub clutch and a brake control valve (18), (19) provided with a connection position and a position connected to a hydraulic power source (17), and a brake release side pressure port of both the clutch and the brake control valve; A hydraulic valve (20) having a switching position between the hydraulic pressure source and a permanent position for connecting the brake release side pressure port to the tank;
Is inserted into the hydraulic circuit between the directional control valve and the counterbalance valve or the hydraulic circuit for operating the directional control valve, while the directional control valve is switched to the motor drive position for lifting or lowering. Only the first shuttle valve (21) for generating the pilot oil pressure is connected, and upon receiving the pilot oil pressure generated by the first shuttle valve, the primary side of the check valve (6) and the pilot valve (4) are connected to the primary side. A pilot operating portion for switching the switching valve (8) is attached to the switching valve (8) so that the pilot oil passage (7) provided therebetween is connected to the tank, and the pilot operation of the switching valve (8) is performed by the first shuttle valve. A second shuttle valve (22) for taking out the pilot hydraulic pressure for switching the hydro valve (20) is connected between the pilot oil passage to the section and the primary oil passage of the check valve (6).

[Action]

Since the present invention has the above configuration, when raising and lowering a kelly bar or the like of an earth drill by a winch motor of a jib crane, a pilot oil passage between the primary side of the check valve (6) and the pilot check valve (4). If the switching valve (8) is previously switched so that (7) is connected to the tank, not only the check valve (6) is closed, but also the directional switching valve (2) is switched from the neutral position to winch motor. When the winch motor is driven down, the pilot valve (4) is closed, and when the winch motor is driven down, the relief valve (5) operated by the primary hydraulic pressure of the pilot check valve is closed. Thus, the winch motor can be controlled as in the conventional case.

When the winch motor is driven down until the drilling bucket or the like at the lower end of the kelly bar contacts the ground, when the directional control valve (2) is returned to the neutral position, the pilot oil passage (7) is connected to the relief valve (5). The switching valve (8) is manually switched so as to be connected to a hydraulic source such as a hydraulic pump that generates a pressure higher than the pilot set pressure. Then, the hydraulic pressure of the hydraulic power source supplied by opening the check valve (6) to the high-pressure side oil passage at the time of hoisting in which the counterbalance valve (3) and its attached check valve (3a) are closed is Since the return oil flows into the winch motor and the return oil is discharged to the tank from the directional control valve (2) in the neutral position, the winch motor is rotated and energized in the hoisting direction, and at the same time, the pilot check valve (4) is turned on. Since it is opened by the hydraulic pressure of the passage (7), the relief valve (5) is opened to maintain the pressure of the high-pressure side oil passage at the time of hoisting at a pressure capable of preventing turbulence of the winding drum.

For this reason, even if the bobbin rope between the bobbin and the pulley at the end of the boom is slack, the bobbin bobbin winds up the bobbin rope until a constant tension that prevents turbulent winding is generated. Moreover, when the kelly bar is driven and rotated by the rotary table and drilled with a drilling bucket or the like, as the drilling progresses, if a large suspension load of the kelly bar or the like is applied to the end of the bobbin rope, the suspension is performed. The winch motor driven in the lowering direction by the load rotates by overcoming the motor back pressure given by the hydraulic pressure source, and the winding rope of the winding drum is always extended from the winding drum with a constant tension as the drilling proceeds. Is done.

In order to discharge the excavated soil filled in the drilling bucket or the like by drilling operation, when lifting the kelly bar and the drilling bucket on the ground, the switching valve (8) is switched, and the pilot oil passage (7) is placed in the tank. , The winch motor can be controlled by the direction switching valve (2).

However, the directional control valve (2) or its operating mechanism is provided with a device for generating a pilot oil pressure or a signal only while the directional control valve (2) is being switched to the motor driving position, and the pilot oil passage (7) is opened by the pilot oil pressure or the signal. If a switching device connected to the tank is provided in the switching valve (8), the switching valve (8) is automatically switched to connect the pilot oil passage to the tank by switching the direction switching valve to the motor drive position. Therefore, the operation of switching the switching valve at the time of discharging the excavated soil is not required. In addition, since no pilot oil pressure or signal is generated at the neutral position of the directional control valve, the directional control valve can be freely switched.

In order to selectively drive one of the main and sub-winding cylinders with one winch motor, a clutch cylinder capable of connecting a always-cut clutch provided between each of the winding cylinders and its drive shaft. (13), (14), brake cylinders (15), (16) provided for each of the winding cylinders, each of which can release a constant braking type brake, and the clutch cylinder and the brake cylinder of both the main and sub winding cylinders. A main / sub clutch and a brake control valve (18), (19) provided with a position connected to the tank and a position connected to the hydraulic pressure source (17), respectively, are provided for the clutch cylinder and the brake cylinder of the required winding drum. When the supply and discharge of hydraulic pressure are enabled, the aforementioned hydro valve (20) is inserted between the hydraulic port (17) and the pressure port of the clutch and brake control valve, and the direction switching valve (2) and the counter are inserted. Between the balance valve A first shuttle valve (21) which can take out a pilot hydraulic pressure for operating the switching valve (8) only while the direction switching valve is at the motor drive position is connected to the pressure circuit or the hydraulic circuit for operating the direction switching valve. A pilot oil passage between the first shuttle valve and the switching valve (8) and a check valve (6).
A second shuttle valve (22) for taking out the hydraulic pressure for switching the hydraulic valve is connected between the first hydraulic passage and the primary oil passage. Then the clutch and brake control valve (1
8) is switched so that the clutch cylinder and the brake cylinder are connected to the hydraulic pressure source (17) to connect the clutch, and when the directional control valve (2) is switched from the neutral position to the motor drive position, Since the switching valve (8) is switched and energized by the pilot oil pressure taken out of the first shuttle valve, the switching valve at the position connecting the pilot oil passage (7) to the hydraulic pressure source is connected to the tank. Is switched to
Close the pilot check valve (4) and the check valve (6).
At the same time, the pilot oil pressure taken out of the first shuttle valve is passed through the second shuttle valve to act on the pilot operating portion of the hydro valve (20) to switch the hydro valve to the switching position, so that the brake cylinder is connected to the hydraulic source. As a result, the brake is released, and the winch motor drives the winding drum to raise and lower the kelly bar and the like.

Also, when the winch motor is stopped by returning the directional control valve from the motor drive position to the neutral position, the first shuttle valve does not generate any pilot hydraulic pressure. Connect to
Accordingly, the winding drum brake is actuated to restrain the lifted or suspended kelly bar or the like at that position, but the winding drum clutch remains connected.

Therefore, in the case where the suspended kerry bar and the drilling bucket grounded by the rotary table are driven and rotated by the rotary table to pierce, the switching valve (8) is switched while the direction switching valve is in the neutral position, and the check is performed. On the primary side of the valve (6), a relief valve (5)
If a hydraulic pressure equal to or higher than the pilot set pressure is supplied, the hydraulic pressure is taken out from the second shuttle valve (22) and the hydraulic valve (2
Since 0) is switched to the switching position, the winding drum brake is released. At the same time, as described above, the tension of the bobbin rope is maintained at a constant tension by the action of the relief valve (5) so that it does not become turbulent.

〔Example〕

FIG. 1 shows an embodiment of the present invention in a case where a winding drum (23) is constantly connected to a winch motor (1), and a high pressure side during winding between the winch motor and a directional control valve (2). The pilot oil passage 25 of the counterbalance valve 3 inserted into the oil passage 24 is connected to the oil passage 26 on the opposite side. 3a shows a check valve provided in the counter balance valve. Oil passages 24, 26 on both sides between winch motor and counterbalance valve
A pilot check valve 4 and a relief valve 5 are connected in series, and a check valve 6 having a secondary side connected to the oil passage 24.
A pilot oil passage 7 provided between the primary side of the pilot check valve 4 and the pilot operating section of the pilot check valve 4 is selectively connected to the tank T and the discharge port of the hydraulic pump 27 via a manual switching valve 8.

The hydraulic pump 28 and the hydraulic pump 27 that supply the hydraulic pressure to the center bypass type directional switching valve 2 are, together with a hydraulic pump (not shown) for operating other hydraulic equipment of the jib crane, an engine 29 controlled by an all-speed governor. Driven. 30
Is a winch protection relief valve connected between the oil passages 24 and 26 on both sides between the winch motor and the counterbalance valve, and the pilot set pressure of the relief valve 30 is a pump protection pressure connected to the discharge port of the hydraulic pump 28. Relief valve 31 for
Higher than the pilot set pressure.

In the figure, 32 is a relief valve connected to the discharge port of the hydraulic pump 27, 33 is a center bypass oil passage of the direction switching valve 2, 34 is a drain oil passage of the winch motor 1, 35 and 36 are filters,
Since the pressure capable of preventing the winding rope from being turbulent is lower than the hydraulic pressure required for driving up or down the winch motor, the discharge hydraulic pressure of the hydraulic pump 27 may be reduced by the source pressure valve and supplied to the switching valve 8. it can.

The automatic switching device for the switching valve 8 in FIG. 1 is configured such that a shuttle valve 21 is connected between oil passages 24 and 26 on both sides between the directional switching valve 2 and the counterbalance valve 3 to switch the output port of the shuttle valve. Pilot oil passage between pilot operation part of valve 8
Although connected by 37, the shuttle valve 21 can also be directly assembled on the output side of the directional control valve 2. For this reason, the hydraulic pressure in the high-pressure side oil passage 24 during the hoisting drive of the winch motor is taken out from the shuttle valve 21 to switch the switching valve 8 and connect the primary side of the check valve 6 to the tank T. When the switching valve 8 is manually switched so that the primary side of the check valve 6 is connected to the hydraulic pump 27 at the neutral position of the directional switching valve 2, the hydraulic pressure of the pilot operating portion of the switching valve is reduced by the shuttle valve 21. And directional control valve 2
Are sequentially discharged to the tank T.

The automatic switching device of the switching valve 8 is not limited to the configuration shown in FIG. 1, but as shown in FIG.
38, 39 are selectively controlled by an operation lever 40, and a low-pressure hydraulic source 43 such as an accumulator is connected to one of pilot oil passages 41, 42 on both sides of the directional control valve 2 normally connected to the tank T. In the case of a winch motor control device in which hydraulic pressure is supplied to switch the directional control valve to a motor drive position for lifting or lowering, a shuttle valve 21 for extracting pilot hydraulic pressure for switching the switching valve 8 is connected to the pilot valve on both sides. It can be connected between the oil passages 41 and 42. In FIG. 2, members denoted by the same reference numerals as those in FIG. 1 are corresponding members.

Making the automatic switching device of the switching valve 8 hydraulically operated is not a necessary condition of the present invention at all. When the operation lever of the directional switching valve 2 is switched to either the hoisting or the lowering motor drive position, the operation is not performed. A switch that emits a signal in conjunction with the lever may be provided, and a solenoid-operated switching device that switches the switching valve 8 so that the primary side of the check valve 6 is connected to the tank by the signal may be provided in the switching valve. .

FIG. 3 shows that the output shaft of the winch motor 1 is interlocked with the drive shafts 11 and 12 of the main and sub winding cylinders 9 and 10 via a reduction gear mechanism.
A clutch cylinder 13 on the side of the main winding drum 9 which can be connected to a clutch which is provided between the main winding cylinder 9 and the drive shaft 11 and which is always cut and energized.
And an embodiment in which a brake cylinder 15 capable of releasing a winding cylinder brake that is constantly energized is mounted, and a similar clutch cylinder 14 and a brake cylinder 16 are also mounted on the sub-winding cylinder 10 side. Between the clutch cylinder 13 and the brake cylinder 15 and the clutch and brake control valve 18,
There is provided a hydro valve 44 having a constant position for connecting the brake cylinder to the tank T and a switching position for connecting the brake cylinder to the clutch and the brake control valve 18. The pilot operation oil passage 45 is connected to the clutch cylinder. . It is clear from the drawing that a similar hydro valve 46 is provided between the clutch cylinder 14 and the brake cylinder 16 and the clutch and brake control valve 19, and the pilot operation oil passage 47 is connected to the clutch cylinder. It is.

Therefore, when each clutch and the brake control valves 18 and 19 are at the lower position in the drawing connecting the corresponding clutch cylinder and brake cylinder to the tank T, the hydro valve 4
Since no pilot oil pressure acts on 4,46, the hydro valve connects the brake cylinder to the tank as shown, the clutch is disconnected, and the brake is braking the winding drum. However, when one of the clutches and the brake control valve, for example, 18 is switched to the upper position in the figure, the brake release side pressure port is connected to the tank by the hydro valve 20, so that only the pressure port on the clutch connection side is like a high pressure accumulator. The hydraulic pressure of the hydraulic pressure source 17 is supplied, the clutch is connected by the clutch cylinder 13, and at the same time the hydro valve 44 is switched to the switching position by the pilot hydraulic pressure.
Is not supplied, and the winding drum remains braked.

The brake of the winding drum 9 is released such that the first shuttle valve 21 generates pilot oil pressure by driving the winch motor 1 by switching the direction switching valve 2 to a motor drive position for lifting or lowering. And the switching valve 8 is switched so as to supply the discharge oil pressure of the hydraulic pump 27 to the primary oil passage 48 of the check valve 6 at the neutral position of the directional control valve 2 so that the pump discharge oil pressure is reduced to the second shuttle. Only in both cases, the second shuttle valve 22 supplies the pilot hydraulic pressure to the hydro valve 20 via the oil passage 49, and the hydro valve 20 is switched to the lower position in the figure. To supply the hydraulic pressure of the hydraulic pressure source 17 to the brake cylinder 15,
Release the winding drum brake. In FIG. 3, members denoted by the same reference numerals as those in FIG. 1 indicate corresponding members.

〔The invention's effect〕

Since the present invention has the configuration described above, the following effects can be obtained.

A pilot check valve (4) and a relief valve (5) are connected in series between the high pressure side oil passage and the low pressure side oil passage during winding between the winch motor and the counter balance valve,
And a switching valve (8) through the check valve (6) to the high-pressure side oil passage.
According to the invention, when the primary side of the check valve (6) is communicated with the tank by the switching valve, the check valve (6) is driven when the winch motor is driven up or down by the direction switching valve.
And pilot check valve (4) or relief valve (5)
Is closed and the switching valve (8) is in the neutral position of the directional control valve
When the primary side of the check valve is connected to a hydraulic pressure source, the check valve, the pilot check valve and the relief valve (5) are opened, and the high pressure during the winding between the winch motor and the counterbalance valve is increased. Since the oil pressure in the side oil passage is maintained at a pressure that can prevent turbulence of the bobbin rope, when raising and lowering the kelly bar by the bobbin, only the directional control valve is operated, and the grounded kelly bar is driven to pierce. In such a case, the switching valve (8) only needs to be switched when stopping the descent of the kelly bar due to the perforation, and it is not necessary to keep operating the switching valve, and the operation becomes easy. Even if the bobbin rope is loose when the kelly bar or the like lowered by the winch motor is grounded, the switching of the switching valve (8) not only takes up the bobbin rope with hydraulic pressure that can prevent turbulent winding, but also boring. During this time, the winding rope keeps the tension for preventing turbulence, so that there is no risk of the winding drum becoming turbulent, and an operator who warns the crane driving vehicle of the turbulent winding state of the winding drum is not required.

The output side of the directional control valve or its operating mechanism is provided with a device for generating a pilot hydraulic pressure or a signal only while the directional control valve is being switched to the motor drive position, and the check valve (6) is operated by the pilot hydraulic pressure or the signal. If the switching valve (8) is automatically switched so as to connect the primary side to the tank, it is only necessary to switch the switching valve at the start of drilling, so that it is not only necessary to switch the switching valve when drilling is stopped, When hydraulic pressure is supplied to the primary side of the check valve (6) and the pilot check valve (4) and the relief valve (5) are open, there is no possibility that the winch motor will be erroneously hoisted and driven when the pilot check valve (4) and the relief valve (5) are open. Control becomes easier.

Further, when the main and sub winding cylinders are each provided with a clutch cylinder for connection of a clutch which is always constantly energized and a brake cylinder for releasing a brake which is always energized, a first shuttle valve (21) is used to switch to a switching valve. By merely providing a second shuttle valve (22) for taking out the pilot oil pressure for switching the hydro valve between the pilot oil passage of the first embodiment and the primary oil passage of the check valve (6), it is possible to carry out the above-described winding operation when the winch motor is driven. In any case when the trunk cable is not loosened, the bobbin clutch can be automatically connected to release the bobbin brake, and the control of the crane bobbin becomes easy, and the unskilled crane operator But it can be used efficiently.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of one embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram showing another embodiment of an automatic switching device for a switching valve, FIG.
The figure is a hydraulic circuit diagram showing an embodiment in which both the main and sub winding cylinders are provided with an automatic clutch and an automatic brake, respectively. 23 ... Winding cylinder, 24 ... High-pressure side oil passage when hoisting, 26 ... Low-pressure side oil passage when hoisting, 27,28 ... Hydraulic pump, 29 ... Engine, 33 ... Center bypass oil passage , 38, 39… Pilot valve, 40… Operating lever, 41, 42… Pilot oil passage, 43
…… Low-pressure hydraulic pressure source, 48 …… Primary oil passage of check valve.

Claims (3)

(57) [Claims] An apparatus for controlling a crane winding drum in which a counterbalance valve (3) is inserted into a high pressure side oil passage at the time of hoisting between a winch motor (1) and a center bypass type directional switching valve (2), A pilot check valve (4) between the high-pressure side oil passage and the low-pressure side oil passage at the time of winding between the winch motor and the counterbalance valve, which can prevent the flow from the high-pressure side oil passage to the low-pressure side oil passage. ) And a relief valve (5) which is opened by the pilot oil pressure when the hydraulic pressure on the primary side of the pilot check valve reaches a pressure at which the winding rope can be prevented from being turbulently connected, and the high pressure side oil passage is connected. A position for supplying a hydraulic pressure equal to or higher than a pilot set pressure of the relief valve (5) through the check valve (6), a primary side of the check valve (6) and the pilot check valve (4). Pilot oil placed between A switching valve (8) having a position for connecting (7) to the tank, wherein the pilot set pressure of the pilot check valve and the check valve is set lower than the pilot set pressure of the relief valve (5). Characteristic crane winding cylinder control device. 2. A device for generating a pilot oil pressure or a signal is provided on the output side of a winch motor control directional switching valve (2) or on its operating mechanism only while the winch motor is being switched to a hoisting or lowering motor drive position. In response to the pilot oil pressure or signal, switching is performed so that the primary side of the check valve (6) and the pilot oil passage (7) provided between the check valve and the pilot check valve (4) are connected to the tank. A switching device for switching the valve (8) is provided in the switching valve.
A control device for a crane winding drum as described in the above. 3. The drive shafts (11) and (12) of the main and sub-winding cylinders (9) and (10), which are operatively connected to the output shaft of one winch motor (1), and the respective drive shafts. The clutch cylinders (13) and (14), which can be connected to the clutch provided by always cutting and energizing between the and the corresponding winding cylinders, and the brakes that are always energized and are provided on both the main and sub winding cylinders Main and auxiliary clutches provided with releasable brake cylinders (15) and (16), and positions for connecting the clutch cylinders and the brake cylinders of both winding cylinders to a tank and a position for connecting to a hydraulic power source (17), respectively. And a brake control valve (18), (19) provided in the control device for the crane winding drum, and a switching position for connecting between the clutch release and the brake release side brake port of the brake control valve and the hydraulic pressure source. And the brake release side pressure port are connected to the tank A hydraulic valve (20) having a time position is inserted, and the directional control valve is wound up or down in a hydraulic circuit between the directional control valve and the counterbalance valve or a hydraulic circuit for operating the directional control valve. A first shuttle valve (21) for generating a pilot oil pressure is connected only while the motor drive position is switched to the first position, and upon receiving the pilot oil pressure generated by the first shuttle valve, the primary side of the check valve (6) and the A pilot operating portion for switching the switching valve (8) is mounted on the switching valve so that the pilot oil passage (7) provided between the switching valve and the pilot check valve (4) is connected to the tank, and the first shuttle valve is provided. A second shuttle valve (22) for taking out the switching hydraulic pressure of the hydro valve (20) between the pilot oil passage to the pilot operating portion of the switching valve (8) and the primary oil passage of the check valve (6). ) Connected claims The control device of the crane winding cylinder according.