JP2002226182A - Control device of hydraulic winch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve free-fall operation of a winch by utilizing the lowering stop action when the winch touches the ground based on the structure of driving a hydraulic motor for driving a winch drum with a closed circuit. SOLUTION: A selector valve 13 is mounted in an inclined rotation control circuit 12 on the lowering side of an inclined rotating cylinder 5 for controlling a pump 4. When a holding pressure P1 on the lowering side is lower than a set value for the stop of lowering as the winch drum touches the ground in the free-fall operation of the winch drum to be rotated for lowering at a high speed, the selector valve 13 is switched to a lowering stop position (a) and the flow of spout from the pump is zero, so that the rotation of a motor 1 for lowering is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a hydraulic winch in which a hydraulic motor is driven by a hydraulic pump and a winch drum is rotated by the hydraulic motor.

[0002]

2. Description of the Related Art Conventionally, as a control device of a hydraulic winch,
As shown in JP-B-63-35555,
The winch drum is equipped with a clutch and both negative and positive brakes, and controls on / off of these clutches and brakes according to the driving, stop, and free fall (free fall of suspended load) operating conditions of the winch drum. It is known.

However, according to this device, since the power transmission path by the clutch is cut off and the suspended load is lowered by the brake pedal, it requires skill to perform an accurate operation.
Further, since a clutch, a positive brake, and a control system for these are required for free fall, there are drawbacks in that the device configuration is complicated and the cost is increased.

[0004]

Therefore, as disclosed in Japanese Patent Application Laid-Open No. H11-79679, the present applicant sets the motor to a small capacity and rotates the motor at the high speed to lower the free fall. A technology that enables similar high-speed hoisting operation (hereinafter referred to as free fall operation) has been proposed.

[0005] In this free fall operation, the motor rotates down at high speed, and when the suspended load (or hook) reaches the ground (landing), the hoisting rope does not become loose or turbulent winding does not occur. Thus, two functions of stopping the lowering rotation are required.

[0006] However, the above proposed technique presupposes an open circuit in which a motor circuit is connected to a pump and a tank, and a closed circuit, that is, both side pipes of a motor are connected to both discharge ports of a two-way pump. In a circuit that changes the rotation direction and speed of the motor by controlling the oil discharge direction and discharge flow rate, the technology for enabling the free fall operation having the above two functions has not yet been realized.

Accordingly, the present invention provides a hydraulic winch control device which enables free fall operation in a closed circuit.

[0008]

According to a first aspect of the present invention, a hydraulic motor for driving a winch drum and a hydraulic pump as a hydraulic source for the hydraulic motor are connected by a closed circuit. Motor speed switching means for switching between a high-speed rotation mode for high-speed lowering rotation and a low-speed rotation mode for relatively low-speed rotation, lowering operation means for outputting a lowering command signal, and oil for the hydraulic pump Pump control means for controlling a discharge direction and a discharge flow rate of the motor is provided.The pump control means is provided in a state where the motor speed switching means is set to a high-speed rotation mode and the lowering operation means is operated to lower the lowering operation. When the lowering side holding pressure of the closed circuit falls below the set value of the lowering stop, the hydraulic pump stops rotating and the hydraulic pump is controlled in the direction in which the lowering operation stops. It has been made.

According to a second aspect of the present invention, in the first aspect, a variable displacement type hydraulic pump is used as the hydraulic pump, and the pump control means controls the lowering tilt of the lower side of the hydraulic pump. A switching valve is provided in the lower-side tilt control circuit. The switching valve is provided at a lower position where the hydraulic motor rotates lower and a lower position at which the lower rotation of the hydraulic motor stops. A lower stop position, and is configured to switch from the lowering position to the lowering stop position when the lowering side holding pressure falls below a set value of the lowering stop.

According to a third aspect of the present invention, in the configuration of the second aspect, the switching valve is configured such that the total value of the lowering side holding pressure and the lowering command pressure by the lowering operation of the lowering operation means sets the lowering start. It is set to the lower position when it reaches the value.
The lowering rotation speed is controlled in accordance with the lowering command pressure.

According to a fourth aspect of the present invention, in the configuration of the second or third aspect, a hydraulic pilot type switching valve is used as the switching valve.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the lowering-side holding pressure and the lowering command pressure by the operation of the lowering operation means are respectively applied to the hydraulic pilot port of the switching valve. It is configured to be introduced as a pilot pressure in a direction to be set to the lower position.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the pilot port of the switching valve has a first port for introducing a lowering-side holding pressure and a second port for introducing a lowering command pressure. The pressure receiving area of the first port is set smaller than the pressure receiving area of the second port.

According to a seventh aspect of the present invention, in the configuration of the second or third aspect, an electromagnetic switching valve is used as the switching valve,
Further, the controller is provided with a controller for outputting a switching signal to the lowering stop position to the switching valve when the lowering side holding pressure falls below the set value of the lowering stop.

According to an eighth aspect of the present invention, in the configuration of the seventh aspect, the controller sends the switching valve a total value of (a) the lowering-side holding pressure and the lowering command pressure reaches the set value of the lowering start. Outputs a switching signal to the lowering position to the switching valve when
It is configured to output a signal in a direction in which the lowering rotation speed changes according to the lowering command pressure.

According to a ninth aspect of the present invention, in the configuration of any one of the first to eighth aspects, a mode switching means for switching a lowering mode between an automatic stop mode and a normal mode is provided.
The pump control means (a) in the state where the mode switching means is set to the automatic stop mode, stops the lowering operation when the lowering side holding pressure falls below the set value of the lowering stop,
(B) When the mode switching means is set to the normal mode, the hydraulic pump is controlled in the direction in which the lowering operation is performed regardless of the value of the lowering side holding pressure.

According to the above construction, when the motor speed switching means is set to the high-speed rotation mode and the lowering operation means is operated to lower the winch, the winch drum is rotated down at a high speed to perform a free fall operation. .

During the free fall operation, the suspended load lands and the lowering side holding pressure of the closed circuit drops below the set value of the lowering stop (it becomes 0 in the completely landing state where the load is removed). Then, the lowering rotation of the motor is stopped by the pump control means.

In this case, according to the third to eighth aspects,
When the switching valve is switched from the lowering position to the lowering stop position, the tilting of the variable displacement hydraulic pump is set to the discharge flow rate of 0, and the lowering operation is stopped.

In this way, in the closed circuit, two functions of high-speed lowering rotation and landing stop are exhibited, and free fall operation becomes possible.

According to the third, fifth and eighth aspects of the present invention,
The free fall operation is started when the total value of the lowering side holding pressure and the lowering command pressure by the lowering operation reaches the set value of the lowering start, and according to the lowering command pressure (lowering operation amount). Is controlled to the lowering speed. Therefore, the speed during the free fall operation can be freely controlled by the operator.

According to the fourth and sixth aspects of the present invention, a hydraulic pilot type switching valve is used as the switching valve, and full hydraulic control is possible. (E.g., a controller or a pressure detection unit) is not required, and the circuit can be configured only with hydraulic devices.

In this case, according to the configuration of the sixth aspect, in the switching valve, the pressure receiving area of the first port to which the high pressure lowering side holding pressure is introduced is small, and the second pressure to which the low pressure lowering command pressure is introduced. Because the pressure receiving area of the port is set large,
The lowering speed control according to the lowering operation amount is easily performed. Further, since the spring force against the lower holding pressure can be reduced, the switching valve can be made compact.

On the other hand, according to the seventh and eighth aspects of the present invention, an electromagnetic switching valve is used as the switching valve, and the switching valve can be directly controlled by an electric signal, and a hydraulic switching valve having a special pilot port is used. Compared with, general-purpose valves can be used, so component costs are low and
The device configuration is simple.

Further, since the switching command of the switching valve is issued by the controller, the switching characteristics of the switching valve can be freely selected in a wide range.

On the other hand, according to the ninth aspect of the present invention, in contrast to the first to seventh aspects of the present invention, the lowering is always stopped at the time of landing. The hoisting operation can be continued even if the load is landed.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

First Embodiment (See FIGS. 1 to 3) In FIG. 1, reference numeral 1 denotes a variable displacement type hydraulic motor for driving a winch drum (not shown). 2 and 3 are directly connected to both discharge ports of a variable displacement and two-way discharge type hydraulic pump 4 to form a motor closing circuit A, in which the discharge direction and discharge flow rate of the hydraulic pump 4 are controlled, and the hydraulic motor The rotation direction (winding / winding) and the rotation speed of 1 are controlled.

The structure of the pump control means for controlling the pump 4 will be described.

The tilting cylinder 5 for operating the tilting of the pump 4 upward and downward, and the hydraulic source 6 and the tank T of the cylinder 5 via a cylinder control valve 7 which is a hydraulic pilot type servo valve. The cylinder control valve 7 and the tilting cylinder 5 are controlled by the pressure (remote control pressure) from both the upper and lower remote control valves 9 and 10 operated by the lever 8.

That is, when the lever 8 is operated to the upper side on the right side or the lower side on the left side in the figure, a remote control pressure corresponding to the lever operation amount is output from the upper side remote control valve 9 or the lower side remote control valve 10, and By this remote control pressure, the cylinder control valve 7 is switched from the neutral position A to the hoisting position B on the right side of the drawing or the lowering position C on the left side.

The hydraulic pressure corresponding to the operation amount of the remote control valve is sent to the winding upper oil chamber 5a of the tilting cylinder 5 at the winding position B, and to the lower oil chamber 5b of the tilting cylinder C at the lowering position C. 5 is driven upward or downward to change the tilt, and an amount of oil corresponding to the tilt is sent to the winding pipe 2 or the winding pipe 3 to rotate the motor 1.

Of the upper and lower rewind control circuits 11 and 12 connecting the tilt cylinder 5 and the cylinder control valve 7, a hydraulic pilot type switching valve 13 is provided for the lower reversal control circuit 12.
Is provided.

The switching valve 13 has a lowering stop position a for communicating the lowering-side oil chamber 5b of the tilt cylinder 5 with the tank T,
A lowering position b for sending oil from the hydraulic pressure source 6 to the oil chamber 5b, and a pressure (lower holding pressure) P1 of the lowering line 3 introduced as a pilot port for receiving pilot pressure. It has one pilot port 14 and a second pilot port 15 for introducing a remote control pressure (lowering command pressure) P <b> 2 by operating the lower-side remote control valve 10.

Pistons 16 and 17 as pressure receiving portions which operate by receiving pilot pressures are provided in the two pilot ports 14 and 15 respectively so as to move integrally therewith. The switching valve 13 is switched by the total pressure of the pressure P1 and the lowering command pressure P2.

Here, the pressure receiving areas of the pistons 16 and 17 are such that the first piston 16 receiving a relatively high pressure (lower-side holding pressure P1) is smaller and the second piston receiving a lower pressure (lowering command pressure P2). 17 is set large.

A spring 18 opposes the pilot pressure.

Next, the configuration of the motor speed switching means for increasing the motor speed by setting the capacity of the motor 1 small during the free fall operation will be described.

Reference numeral 19 denotes a displacement adjusting cylinder for changing the displacement of the motor 1 to change the displacement of the motor. The displacement of the motor 1 is set to a large displacement when the cylinder 19 is contracted and to a small displacement when the cylinder 19 is extended. Is done.

The oil chamber 1 on the extension side of the capacity adjusting cylinder 19
9a is connected to the winding line 2 and the tank T via a hydraulic pilot switching capacity control valve 20.

The displacement control valve 20 has a large displacement position A and a small displacement position B. In the large displacement position A, the cylinder extension side oil chamber 19a communicates with the tank T, and the displacement adjusting cylinder 19 contracts (motor). 1 is set to large capacity).

On the other hand, when the control valve 20 is switched to the small-capacity position B, the oil in the upper winding line 2 is discharged to the cylinder extension side oil chamber 19a.
, The cylinder 19 is extended (the motor 1 is set in the small capacity area).

A small capacity pilot port 20a of the capacity control valve 20 is connected to a free fall valve (electromagnetic switching valve) 22 constituting mode switching means via a motor capacity switching line 21.
Connected to the output port.

The free fall valve 22 is set to the non-operating position a in the normal operation (during the hoisting operation and the normal lowering operation). In this state, the displacement control valve 20 is maintained at the large displacement position a shown in the figure. Is done.

In this state, when the free fall switch 23 constituting the mode switching means is turned on, the free fall valve 22 is switched to the operating position B, and the hydraulic pressure of the pilot hydraulic power source 24 is reduced by the small capacity pilot of the capacity control valve 20. The control valve 20 is supplied to the port 20a and switches to the small capacity position B.

As a result, the displacement adjusting cylinder 19 is extended and the motor 1 is set to a small displacement.

The operation of this device will be described.

During the hoisting operation and the normal hoisting operation, the free fall valve 22 is set to the non-operating position A, and the motor capacity is set to a large capacity.

In this state, the operation of the cylinder control valve 7 and the tilting cylinder 5 based on the operation of the remote control valves 9 and 10 on the winding-up side and the winding-down side causes the motor 1 to operate at a speed corresponding to the operation amount (during free fall operation) (Lower speed), and the hoisting operation or the normal hoisting operation is performed.

On the other hand, during the free fall operation, the free fall valve 22 is switched to the operating position B, and the motor capacity is set to a small capacity, so that the lowering operation at a high speed becomes possible.

During the free fall operation, as described above, the total pressure of the lowering side holding pressure P1 and the lowering command pressure P2 is applied to the switching valve 13 as the pilot pressure, and this total pressure is used to set the lowering start. When it reaches the value, it switches to the lowering position b.

This point will be described in detail. Fk: Return spring force of spring 18 at the time of cracking when switching valve 13 switches to lowering position b A1: Pressure receiving area of first piston 16 P1: Lowering side holding pressure A2: When the switching valve 13 switches to the lowering position b in the pressure receiving area P2 of the second piston 17: lowering command pressure, Fk = A1 · P1 + A2 · P2 (1) Therefore, in order for the switching valve 13 to be at the lowering stop position a, Fk> A1 · P1 + A2 · P2 (2). Then, the equation (2) is transformed into P1 <(− A2 · P2 + Fk) / A1 (3), and the equation (3) represents a hatched portion in FIG.

That is, when the coordinates represented by the lowering side holding pressure P1 and the lowering command pressure P2 are within the hatched portion of the graph of FIG. 2, the switching valve 13 is at the lowering stop position a. The cylinder control valve 7 is operated by operating the side remote control valve 10.
Is switched to the lowering position c, the pump 4 is in a neutral state (0 tilt). Therefore, the motor 1 does not rotate because the discharge flow rate of the oil from the pump 4 becomes zero.

Then, the operation amount of the lowering-side remote control valve 10 is increased, and the coordinates represented by the lowering-side holding pressure P1 and the lowering-instruction command pressure P2 are outside the hatched portion of the graph as point X in FIG. When it comes out, the switching valve 13 is switched to the lowering position b, the lowering tilt of the pump 4 is set to a value corresponding to the operation amount of the remote control valve, the motor 1 rotates lowering at high speed, and the free fall operation is started. Done.

During the free fall operation, if the pressure coordinates are present at point X in FIG. 2, in order to stop the rotation of the motor 1, it is necessary to move the pressure coordinates from point X into the shaded area. This coordinate movement is performed by reducing at least one of the lowering side holding pressure P1 and the lowering command pressure P2.

In this apparatus, paying attention to the point that the lowering-side holding pressure P1 decreases to 0 or a value close to it when the load lands, the lowering-side holding pressure P1 is equal to or less than a certain value (pressure at the time of landing). The switching characteristic of the switching valve 13 is set so that the switching valve 13 switches to the unwinding stop position a when the switching valve 13 is lowered.

Thus, at the time of landing, the free fall operation is automatically stopped even if the remote control valve 10 is operated to lower the vehicle.

That is, in a closed circuit configuration, a free fall operation having two functions of a high speed lowering rotation and a lowering stop at landing can be performed.

As shown in FIG. 2, since the pump tilt (pump discharge flow rate) changes according to the operation amount of the lowering-side remote control valve 10 (lowering command pressure P2), the lever operation shown in FIG. The free fall speed can be arbitrarily controlled outside the shaded portion.

In this case, both pistons 16 of the switching valve 13,
Since the pressure receiving area 17 is set small on the first piston side and large on the second piston 17 side, the speed change with respect to the change in the lowering command pressure P2 becomes large, and the speed controllability by lever operation is good. Become.

Second Embodiment (see FIG. 4) Only differences from the first embodiment will be described.

In the first embodiment, when the lowering pressure P1 becomes lower than the set value during the lowering operation, the switching valve 13 is always switched to the lowering stop position a and the lowering operation is automatically stopped. On the other hand, in the second embodiment, the mode is switched so that the lowering operation can be continued even if the lowering-side holding pressure P1 falls below the set value.

That is, an electromagnetic switching control valve 26 is provided between the second pilot port 15 of the switching valve 13, the lower remote control valve 10 and the pilot hydraulic power source 24, and the switching control valve 26 is controlled. Controller 2
7, a pressure gauge 28 for detecting the lowering command pressure P2 and inputting it to the controller 27, and a mode for switching the lowering mode between an automatic stop mode for automatically stopping the lowering operation and a normal mode for not automatically stopping. A mode changeover switch 29 is provided as switching means.

The switching control valve 26 is provided with the lower remote control valve 10.
Has a first position A for sending the lowering command pressure P2 to the second pilot port 15, and a second position B for sending the pressure of the pilot hydraulic pressure source 24 directly to the port 15 without reducing the pressure. I have.

The switching control valve 26 is set to the first position A shown in the figure when the mode switching switch 29 is off. In this state, as described in the first embodiment, the lowering operation automatically stops when the lowering-side holding pressure P1 falls below the set value.

On the other hand, when the mode switch 29 is turned on, the switch control valve 26 is switched to the second position B by a signal from the controller 27. In this state, since the pressure from the hydraulic pressure source 24 is supplied to the second pilot port 15 of the switching valve 13, the switching valve 13 is maintained at the lowering position b regardless of a change in the lowering-side holding pressure P1. Is done.

For this reason, even if the load is landed, the lowering operation according to the lowering operation amount is continued as long as the lowering operation is performed.

Such an operation mode is used, for example, in a work of free-falling a crushed rock bar to break rocks in water, when the crushed rock bar is required to continue to be rolled down for a certain period of time after the rock has reached the rock and to be surely crushed. Etc. can be used.

Third Embodiment (see FIG. 5) In the third embodiment, an electromagnetic switching type switching valve 30 is used instead of the hydraulic pilot type switching valve 13 of both the first and second embodiments. The valve 30 is configured to be controlled by a signal from the controller 31.

The controller 31 receives a lowering-side holding pressure P1 by a pressure gauge 32 and a lowering command pressure P2 by a pressure gauge 33, respectively.
When the total value reaches a set value or more, a switching signal is output from the controller 31 to the switching valve 30 to switch the switching valve 30 to the lowering position b, and when the lowering-side holding pressure P1 falls below the set value, The switching signal from the controller 31 stops, and the switching valve 30 returns to the lowering stop position a.

According to this configuration, a general-purpose solenoid valve is used in comparison with the case where the special switching valve 13 having the first and second pilot ports 14 and 15 is used as in the first and second embodiments. Can be used, the component cost is low and the device configuration is simple.

Since the switching command of the switching valve 30 is issued by the controller 31, the switching characteristics of the switching valve 30 can be freely selected in a wide range.

Fourth Embodiment (See FIG. 6) In each of the above embodiments, the tilting cylinder 5 is indirectly controlled by the remote control valves 9 and 10 via the cylinder control valve 7. In the fourth embodiment, the cylinder control valve 7 is omitted, and the remote control pressure from the remote control valves 9 and 10 is directly sent to the tilting cylinder 5 via the cylinder control lines 34 and 35 (the lower side is via the switching valve 13). ,
Direct tilt cylinder 5 by operating remote control valves 9 and 10
Is controlled.

With this configuration, it is possible to obtain basically the same functions and effects as those of the first to third embodiments.

In each of the above embodiments, the motor speed is switched between high speed and low speed by changing the motor capacity. However, other motor speed switching means, for example, the speed change between the motor 1 and the winch drum is performed. A mechanism may be provided to switch the transmission mechanism between a high speed side and a low speed side.

[0076]

As described above, according to the present invention, during the free fall operation in which the winch drum is rotated down at a high speed, if the lowering pressure of the closed circuit lowers below the set value of the lowering stop, the pump is turned off. The pump is controlled by the control means in a direction in which the lowering rotation of the motor is stopped. (According to the inventions of claims 3 to 8, the switching valve switches from the lowering position to the lowering stop position to incline the variable displacement hydraulic pump. In this configuration, the automatic lowering operation at the time of landing can be obtained, which is the condition of the free fall operation in parallel with the high speed lowering operation. That is, free fall operation can be realized in a closed circuit.

According to the third, fifth, and eighth aspects of the present invention,
The free fall operation is started when the total value of the lowering side holding pressure and the lowering command pressure by the lowering operation reaches the set value of the lowering start, and the lowering speed changes according to the lowering command pressure. Therefore, the free fall speed can be freely controlled by the operator. Therefore, the operability during the free fall operation is improved.

According to the fourth to sixth aspects of the present invention, since the hydraulic pilot type switching valve is used as the switching valve and full hydraulic control is possible, compared with the case where the electromagnetic switching valve is used,
Equipment for electrical control (controller and pressure detection means)
Becomes unnecessary, and the circuit can be constituted only by hydraulic devices.

In this case, according to the invention of claim 6, in the switching valve, the pressure receiving area of the first port to which the high-pressure lower-side holding pressure is introduced is small, and the second pressure to which the low-pressure lowering command pressure is introduced. Because the pressure receiving area of the port is set large,
The lowering speed control according to the lowering operation amount is easily performed. Further, since the spring force against the lower holding pressure can be reduced, the switching valve can be made compact.

On the other hand, according to the seventh and eighth aspects of the present invention, in which an electromagnetic switching valve is used as the switching valve, the switching valve can be directly controlled by an electric signal, and a hydraulic switching valve having a special pilot port is used. Compared with, general-purpose valves can be used, so component costs are low and
The system configuration is simple.

Further, since the switching command of the switching valve is issued by the controller, the switching characteristics of the switching valve can be freely selected in a wide range.

On the other hand, according to the ninth aspect of the present invention, the lowering operation can be continued, if necessary, irrespective of the change in the lowering side holding pressure.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a range in which a lowering operation is stopped, which is determined by a lowering command pressure and a lowering side holding pressure in the embodiment.

FIG. 3 is a diagram showing a relationship between a lowering command pressure and a pump discharge flow rate in the embodiment.

FIG. 4 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram showing a third embodiment of the present invention.

FIG. 6 is a circuit configuration diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic motor 2 Upper winding line 3 Lower winding line 4 Hydraulic pump A Closed circuit 5 Tilt cylinder constituting pump control means 7 Cylinder control valve 11 Same winding upper tilt control circuit 12 Same winding lower tilt Control circuit 13 Hydraulic pilot type switching valve 14, 15 Pilot port of the switching valve 16, 17 Piston of pilot port 18 Spring of the switching valve 10 Lowering remote control valve as lowering operation means 19 Motor speed switching means Constituent capacity adjusting cylinder 20 Constituent capacity control valve 21 Constituent motor displacement switching line 22 Free fall valve 23 Free fall switch 26 Switching control valve constituting pump control means 27 Controller 28 Pressure gauge 29 Mode as mode switching means Changeover switch 30 Electromagnetic switching type changeover valve constituting pump control means 31 La 32, 33 Pressure gauge

Claims (9)

[Claims] 1. A high-speed rotation mode in which a hydraulic motor for driving a winch drum and a hydraulic pump as a hydraulic source of the hydraulic motor are connected by a closed circuit, and the hydraulic motor is rotated down at a relatively high speed. Motor speed switching means for switching to a low speed rotation mode for relatively low speed lowering rotation; lowering operation means for outputting a lowering command signal; and pump control for controlling the oil discharge direction and discharge flow rate of the hydraulic pump. Means are provided, wherein the pump control means is configured such that the motor speed switching means is set to a high-speed rotation mode, and
When the lowering operation means is operated to perform the lowering operation, when the lowering side holding pressure of the closed circuit falls below the set value of the lowering stop, the rotation of the hydraulic motor is stopped and the lowering operation is stopped. A control device for a hydraulic winch, characterized in that the control device controls the hydraulic pump in a direction in which the hydraulic winch moves. 2. The hydraulic winch control device according to claim 1, wherein a variable displacement type hydraulic pump is used as the hydraulic pump, and the pump control means controls the lowering tilt of the lower side of the hydraulic pump. A switching valve is provided in the lower-side tilt control circuit. The switching valve is provided at a lower position where the hydraulic motor rotates lower and a lower position at which the lower rotation of the hydraulic motor stops. A lower stop position, and is configured to switch from the lowering position to the lowering stop position when the lowering-side holding pressure drops below a set value of the lowering stop. Hydraulic winch control device. 3. The control device for a hydraulic winch according to claim 2, wherein the switching valve is configured such that the total value of the lowering side holding pressure and the lowering command pressure by the lowering operation of the lowering operation means sets the lowering start. A hydraulic winch control device, which is set to a lowering position when the value reaches a lowering position, and is controlled by this switching valve to a lowering rotation speed corresponding to the lowering command pressure. 4. The hydraulic winch control device according to claim 2, wherein a hydraulic pilot type switching valve is used as the switching valve. 5. The control device for a hydraulic winch according to claim 4, wherein a lowering-side holding pressure and a lowering command pressure by operating a lowering operation means are respectively connected to the hydraulic pilot port of the switching valve. A control device for a hydraulic winch, wherein the control device is configured to be introduced as a pilot pressure in a direction of setting to a lower position. 6. The hydraulic winch control device according to claim 5, wherein the pilot port of the switching valve has a first port for introducing a lowering-side holding pressure and a second port for introducing a lowering command pressure. A pressure receiving area of the first port is set smaller than a pressure receiving area of the second port. 7. The control device for a hydraulic winch according to claim 2, wherein an electromagnetic switching valve is used as the switching valve, and the lowering-side holding pressure falls below a set value of the lowering stop. And a controller that outputs a switching signal to the lowering stop position to the switching valve. 8. The control device for a hydraulic winch according to claim 7, wherein the controller is configured to control the switching valve so that: (a) the total value of the lowering side holding pressure and the lowering command pressure reaches the set value of the lowering start. And a switching signal for switching to the lowering position is output to the switching valve, and a signal in a direction in which the lowering rotation speed changes in accordance with the lowering command pressure is output. Hydraulic winch control device. 9. The hydraulic winch control device according to claim 1, further comprising: mode switching means for switching a lowering mode between an automatic stop mode and a normal mode. (A) In the state where the mode switching means is set to the automatic stop mode, the lowering operation is stopped when the lowering-side holding pressure falls below the set value of the lowering stop. A control device for a hydraulic winch, which is configured to control a hydraulic pump in a direction in which a lowering operation is performed irrespective of a value of a lowering side holding pressure when set to a normal mode.