JP3268173B2 - Winch braking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winch braking device for braking a drum when winding and feeding out a wire by rotating a drum around which the wire is wound.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Publication No. 2-41509, a brake band having a lining attached to an inner peripheral surface thereof is provided, and a brake drum is tightened by the brake band according to operation of a brake pedal. A winch braking device adapted to brake a brake drum is known.

However, in such a device, as in the case where a suspended hammer club or the like is dropped and a pile hole is excavated, when the hammer club or the like is freely dropped and braking is performed by depressing a brake pedal, a brake drum is driven. It gets quite hot. So, to solve this,
As disclosed in JP-A-6-64896, a brake drum is formed integrally with a winch drum, a brake band is wound around the brake drum, and heat dissipation is improved by using a winch drum having a large heat dissipation capacity. Have been.

[0004]

However, in such a conventional apparatus, when the hammer club or the like is dropped and excavated, if the winch drum is not braked immediately after the hammer club has landed, the wire jumps out and the winch drum is wound. As a result, there is a problem that the working efficiency is reduced and the wire is severely damaged. Further, if the winch drum is braked before landing, there is a problem that the bite of the hammer club or the like is reduced and the work efficiency is reduced.

An object of the present invention is to provide a winch braking device that can prevent a wire from jumping out.

[0006]

In order to achieve the above object, the present invention takes the following means to solve the problem. That is, a clutch mechanism for transmitting / cutting off the rotation of the hydraulic motor to the winch drum according to the supplied hydraulic oil, and braking of the winch drum by the urging force of the brake spring, and releasing the brake by the supplied hydraulic oil. Braking mechanism,
A pilot operation switching valve for switching between communication and disconnection between a hydraulic source and the hydraulic motor by supplying a pilot fluid, a pilot valve for switching the supply of the pilot fluid to the pilot operation switching valve, a hydraulic source or a low pressure side, and the brake And a control valve for selectively switching the communication with the clutch mechanism, the winch braking device capable of free fall by releasing the brake mechanism while releasing the clutch mechanism. A semi-braking mechanism for semi-braking the rotation of the winch drum, a semi-braking switching valve for selectively switching the communication between the semi-braking mechanism and the hydraulic oil supply side or the communication between the semi-braking mechanism and the low pressure side, and By supplying the pilot fluid, the communication between the semi-brake switching valve and the hydraulic oil supply side causes the semi-brake switching valve to Brake winch, characterized in that it and a half brake release valve for switching the communication between the low pressure side is it.

A planetary speed reducer for reducing the rotation of the hydraulic motor and transmitting the reduced speed to the winch drum is provided. Of the three rotatable members of the planetary speed reducer, the input member is adapted to supply and discharge hydraulic oil. A brake mechanism for braking the rotation of the vehicle, a winch drum connected to an output member, a clutch / brake mechanism for braking / releasing the rotation according to supply / discharge of hydraulic oil to the remaining members, and a pilot A pilot operation switching valve for switching between communication and disconnection between a hydraulic source and the hydraulic motor by supplying a fluid, a pilot valve for switching supply of the pilot fluid to the pilot operation switching valve, a hydraulic source or a low pressure side, and the brake mechanism And a control valve for selectively switching the communication with the clutch / brake mechanism. A winch braking device capable of free-falling by releasing a brake mechanism, a semi-braking mechanism for semi-braking the rotation of the winch drum with supplied hydraulic oil, and the semi-braking mechanism and the hydraulic oil supply side or the half. A semi-brake switching valve for selectively switching the communication between the braking mechanism and the low-pressure side, and the semi-brake switching valve from the communication between the semi-brake switching valve and the hydraulic oil supply side by the supply of pilot fluid from the pilot valve; A winch braking device comprising a semi-brake release valve for switching to communication with the low pressure side.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, reference numeral 1 denotes a winch drum, and a wire 2 can be wound around the winch drum 1. The winch drum 1 is rotatably supported on a rotating shaft 4 via a pair of bearings 6 and 7, and the rotating shaft 4 includes a pair of bearings 8 and 9.
And is rotatably supported by a main body (not shown).
A large gear 10 is fixed to one end of the rotating shaft 4, and a small gear 14 attached to a hydraulic motor 12 is fixed to the large gear 10.
Are engaged.

The winch drum 1 has a brake drum 1
6 are provided integrally, and a clutch cylinder 18 is provided on the inner peripheral side of the brake drum 16. The clutch cylinder 18 rotates together with the rotating shaft 4, and the clutch band 20 is pressed against the inner periphery of the brake drum 16 by the action of the supplied hydraulic oil, so that the rotation of the rotating shaft 4 can be transmitted to the brake drum 16. . A clutch mechanism 21 is constituted by the clutch cylinder 18 and the clutch band 20.

A brake band 22 is wound around the outer circumference of the brake drum 16, and one end of the brake band 22 is fixed to one end of the fixed side link 2 as shown in FIG.
4 are connected. An end of the fixed side link 24 is swingably supported by a main body (not shown).

The other end of the brake band 22 is connected to a brake lever 26 swingably supported by a main body (not shown). A connecting rod 28 is connected to the brake lever 26 by a pin, and the connecting rod 28 has an elongated hole 30 formed in its end in the axial direction. A pin 34 erected on a brake pedal 32 slidably supported by a main body (not shown) is slidably inserted into the elongated hole 30. When the operator depresses the brake pedal 32, the pin 34
When the pin 34 comes into contact with the end of the elongated hole 30, the connecting rod 28 is pushed when the pin 34 comes into contact with the end of the elongated hole 30.

A pair of pins 38 and 39 are provided upright on the brake lever 26, and one of the pins 38 is slidably inserted into an elongated hole 42 formed in the connecting member 40. . The connecting member 40 is connected to a cylinder rod 46 of a semi-braking cylinder 44 that is supported by a main body (not shown).

A return spring 48 is provided in the semi-braking cylinder 44.
The semi-braking cylinder 44 is configured to protrude the cylinder rod 46 under the action of the supplied operating oil pressure and pull the cylinder rod 46 by the urging force of the return spring 48. In this embodiment, the brake drum 16, the brake band 22, the fixed side link 2
4. The semi-braking mechanism 49 includes the brake lever 26, the pin 38, the connecting member 40, the semi-braking cylinder 44, and the return spring 48.
Is composed.

The other pin 39 is slidably inserted into a long hole 52 formed in the connecting member 50. Connecting member 5
Reference numeral 0 is connected to a cylinder rod 56 of a release cylinder 54 that is supported by a main body (not shown). Also, the connecting member 5
At 0, a spring shaft 58 is connected to the opposite side of the cylinder rod 56, and a washer 62 and a braking spring 64 are interposed between the nut 60 and a main body (not shown) by being screwed into the spring shaft 58. .

The brake lever 26 is moved by the brake spring 64 via the spring shaft 58, the connecting member 50, and the pin 39.
The brake band 22 is urged in the tightening direction. still,
In this embodiment, the brake drum 16, the brake band 2
2, fixed side link 24, brake lever 26, pin 3
9, a coupling member 50, a release cylinder 54, a spring shaft 58, a nut 60, a washer 62, and a braking spring 64 constitute a brake mechanism 66.

On the other hand, as shown in FIG.
Is connected to a hydraulic source (not shown) via a pilot operation switching valve 70. The pilot operation switching valve 70 is switched by a supply of pilot fluid from a pair of hoisting / lowering pilot valves 72 and 74. It is connected to the.

The lifting / lowering pilot valves 72 and 74 are connected so that hydraulic oil from a tank 76 can be supplied under pressure by a hydraulic pump 78.
The relief valve 80 is connected to the discharge side of No. 8. The lifting / lowering pilot valves 72 and 74 are
Operation to selectively raise and lower the pilot valve 7
It is configured such that either one of 2, 74 can be switched.

When the pilot fluid is supplied from the hoisting pilot valve 74, the pilot operation switching valve 70
A winding position 70a for connecting the hydraulic source and the hydraulic motor 12 to rotate the hydraulic motor 12 in a forward direction, and when the pilot fluid is not supplied from either of them, the hydraulic source and the hydraulic motor 12
And a lowering position 70c for connecting the hydraulic source to the hydraulic motor 12 to reversely rotate the hydraulic motor 12 when the pilot fluid is supplied from the lowering pilot valve 72. .

The discharge side of the hydraulic pump 78 is connected to the clutch cylinder 18 via a rotary joint (not shown) via a clutch control valve 84. The clutch control valve 84 is turned on when an excitation signal is input. An open position 84a for communicating the clutch cylinder 18 with a release control valve 90 described later, and a connection position 84b for communicating the hydraulic pump 78 with the clutch cylinder 18 when no excitation signal is input are provided.

Further, the discharge side of the hydraulic pump 78 is connected to the semi-braking cylinder 44 via a semi-braking release valve 85, a pressure reducing valve 86, and a semi-braking switching valve 88.
Is a release position 85a that connects the tank 76 to the semi-brake switching valve 88 via the pressure reducing valve 86 when the pilot fluid is supplied, and the semi-brake switching via the hydraulic pump 78 and the pressure reducing valve 86 when the pilot fluid is not supplied. And a supply position 85b for connecting with the valve 88.

The semi-brake switching valve 88 has a semi-brake position 88a for connecting the hydraulic pump 78 and the semi-brake cylinder 44 via the pressure reducing valve 86 when an excitation signal is inputted, and a semi-brake cylinder 44 when no excitation signal is inputted. And an open position 88b that communicates with the tank 76 as the low pressure side.

The discharge side of the hydraulic pump 78 is also connected to the release cylinder 54 via a release control valve 90 and a brake control valve 92.
When the pilot fluid is supplied from one of the hoisting / lowering pilot valves 72 and 74, the hydraulic pump 78 communicates with the brake control valve 92 and a release position 90 a for supplying the pilot fluid to the semi-brake release valve 85. And a braking position 90b that connects the brake control valve 92 and the tank 76 on the low pressure side when no pilot fluid is supplied from either.

The brake control valve 92 connects the brake position 92a for connecting the release cylinder 54 to the hydraulic pump 78 when the excitation signal is input, and connects the release cylinder 54 to the release control valve 90 when the excitation signal is not input. Release position 92b. In the present embodiment, the clutch control valve 84, the release control valve 90, and the brake control valve 92 constitute a control valve. The control valve is not limited to this, and the release control valve 90 may be provided. Instead, the semi-brake release valve 85 directly introduces pilot fluid from both the pilot valves 72 and 74, and the clutch control valve 84 and the brake control valve 92 discharge the hydraulic pump 78 instead of connecting to the release control valve 90. Side.

Next, the operation of the above-described winch braking device of this embodiment will be described. When hoisting,
The connection position 84b, the release position 88b, and the release position 92b are set without inputting the excitation signal to the clutch control valve 84, the semi-brake switching valve 88, and the brake control valve 92. As a result, the clutch cylinder 18 is connected to the hydraulic pump 78, the clutch cylinder 18 is protruded, the clutch band 20 is pressed against the brake drum 16, and the rotary shaft 4 and the winch drum 1 are connected.

The semi-braking cylinder 44 and the tank 76 are communicated with each other.
So that the swing of the brake lever 26 is not hindered,
The pin 38 is allowed to slide in the slot 42. The release cylinder 54 includes a brake control valve 92 and a release control valve 9.
The brake lever 26 is oscillated by the urging force of the brake spring 64 to tighten the brake drum 16 with the brake band 22 to brake the winch drum 1.

From this state, the operating lever 82 is operated to the hoist side to switch the hoisting pilot valve 74, and the pilot fluid is supplied to the release control valve 90 and the pilot operation switching valve 70. Therefore, the release control valve 90 is switched to the release position 90a, and the hydraulic pump 78 and the release cylinder 54 are communicated via the brake control valve 92,
The cylinder rod 56 is pulled against the urging force of the brake spring 64.

As a result, the urging of the brake lever 26 by the braking spring 64 is released, and the tightening of the brake drum 16 by the brake band 22 is released.
In order not to hinder the swing of the brake lever 26,
Can slide in the elongated hole 52.

On the other hand, the pilot operation switching valve 70 is switched to the winding position 70a, the hydraulic source and the hydraulic motor 12 are communicated, the hydraulic motor 12 is rotated forward, and the small gear 1 is rotated.
4. The winch drum 1 is rotated via the large gear 10, the rotating shaft 4, the clutch band 20, and the brake drum 16, and the wire 2 is wound.

When the operating lever 82 is operated to the lowering side to switch the lowering pilot valve 72, the pilot fluid is similarly supplied to the release control valve 90 and the pilot operation switching valve 70. Therefore, the release control valve 9
0 is switched to the release position 90a, the pilot operation switching valve 70 is switched to the lowering position 70c,
The hydraulic motor 12 is rotated in the reverse direction, the winch drum 1 is rotated, and the wire 2 is paid out.

When the lifting / lowering is stopped, the operation lever 82 is returned, and the brake pedal 32 is depressed by the operator. Therefore, the brake lever 26 is swung through the connecting rod 28, and both pins 38 and 39 are
2 and 52, the brake band 22 is tightened, and the winch drum 1 is braked.

On the other hand, when a hammer club (not shown) suspended from the wire 2 is allowed to fall freely, an excitation signal is input to the clutch control valve 84, and the clutch is switched to the release position 84a to connect the tank 76 and the clutch cylinder 18 with the clutch. Through the control valve 84 and the release control valve 90. Therefore, the pressing of the clutch band 20 against the brake drum 16 is released, and the winch drum 1 can freely rotate with respect to the rotating shaft 4. At this time, the operation lever 82 is in the neutral position, and no excitation signal is input to the semi-brake switching valve 88.

Accordingly, the hammer club pulls out the wire 2 while rotating the winch drum 1 by its own weight, and falls freely. The hammer club is at a predetermined height from the ground, for example, 3
When it falls to a height of about 5 m, the semi-brake switching valve 8
8, an excitation signal is input to switch to the semi-braking position 88a. Therefore, the hydraulic pump 78 and the semi-braking cylinder 44 are connected via the semi-braking switching valve 88, the pressure reducing valve 86, and the semi-braking release valve 85, the cylinder rod 46 is protruded, and the brake lever 26 swings.

As a result, the brake band 22 is fastened to the brake drum 16, and the winch drum 1 is half-braked. This braking force is set in advance by the pressure reducing valve 86, and is enough to stop the winch drum 1 from rotating due to inertia. It is sufficient that a braking force sufficient to brake the rotation of the winch drum 1 due to inertia can be obtained, and the operating hydraulic pressure supplied to the semi-braking cylinder 44 and the cylinder diameter of the semi-braking cylinder 44 are set accordingly.

Therefore, even if the hammer club is partially braked before biting into the ground, the free fall of the hammer club is only braked by a small braking force, and the bite into the ground by the free fall is slightly reduced. . When the hammer club digs into the ground, the winch drum 1 stops rotating due to inertia due to the semi-braking, so that the wire 2 does not fly out and the wire 2 is prevented from being turbulently wound.

The release cylinder 54 has a large cylinder diameter capable of providing a large thrust against the urging force of the braking spring 64. Therefore, the frictional force such as the sliding resistance of the seal member (not shown) is large, and in order to obtain a slight external force,
Operation is unstable even when low-pressure hydraulic oil is supplied. By using the semi-braking cylinder 44 suitable for generating a small thrust, braking can be performed with a braking force small enough to brake the rotation of the winch drum 1 due to inertia.

Thereafter, when the input of the excitation signal to the semi-brake switching valve 88 is stopped, the semi-brake is released. Then, the operating lever 82 is operated to the winding side, the winch drum 1 is rotated forward to wind the wire 2, and the hammer club is lifted,
Hang the hammer club out of the pile hole to discharge the earth and sand.

At this time, even if the operation lever 82 is operated to the winding side while the excitation signal is input to the semi-brake switching valve 88,
The pilot fluid is supplied to the semi-brake release valve 85 via the release control valve 90, and is switched to the release position 85a. Accordingly, the semi-brake cylinder 44 is provided with the semi-brake switching valve 8.
8, the tank 76 via the pressure reducing valve 86 and the semi-brake release valve 85
The semi-braking is released by the return spring 48.

Therefore, even if the operator operates the operation lever 82 while the semi-brake switching valve 88 is energized, the semi-brake mechanism 49
Thus, it is possible to avoid problems such as heat generation due to the rotation of the winch drum 1 with the semi-braking mechanism 49 being half-braked.
The problem caused by an operation error due to the provision of the above can be avoided.

Next, a second embodiment different from the above-described embodiment will be described with reference to FIG. The same members as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the second embodiment, the winch drum 1 is rotationally driven by a hydraulic motor 102 via a planetary reduction gear 100, and the hydraulic motor 102 includes a brake mechanism 104. The planetary reduction gear 100 is meshed with a first sun gear 106 attached to the hydraulic motor 102, a pair of first planetary gears 108 and 110 meshed with the first sun gear 106, and with the first planetary gears 108 and 110. A first internal gear 112 fixed to the inner periphery of the winch drum 1. The first planetary gears 108 and 110 are rotatably supported by the first carrier 114, and the first carrier 114 is rotatably supported around the rotation center of the hydraulic motor 102.

The planetary reduction gear 100 further includes a hydraulic motor 1
02 is provided coaxially with the rotation center of the first carrier 11.
4 is fixed to the second sun gear 116 and the second sun gear 1
16, a pair of second planetary gears 118, 120 meshed with each other.
And a second internal gear 122 meshed with the second planetary gears 118 and 120 and fixed to the inner periphery of the winch drum 1. The second planetary gears 118 and 120 are the second carrier 1
24 and rotatably supported by the second carrier 124.
, A brake drum 16 is integrally mounted.

In the second embodiment, the brake drum 1
6, brake band 22, fixed side link 24, brake lever 26, pin 39, connecting member 50, release cylinder 5
4. The clutch / brake mechanism 125 is constituted by the spring shaft 58, the nut 60, the washer 62, and the braking spring 64.

As described above, the brake band 22 is tightened by the urging force of the brake spring 64 so that the brake drum 16
When hydraulic oil is supplied to the release cylinder 54,
The braking is released. Braking spring 64
When the hydraulic motor 102 is rotated in a state where the second carrier 124 is braked via the brake drum 16 by the urging force of the above, the winch drum 1 is rotated via the planetary speed reducer 100, and the wire 2 is wound up and down. Done.

The brake mechanism 104 is connected to the release control valve 90 so that the brake is released when hydraulic oil is supplied through the release control valve 90. The first sun gear 10 by the brake mechanism 104
When hydraulic oil is supplied to the release cylinder 54 while the brake 6 is being braked to release the braking of the second carrier 124, the winch drum 1 draws out the wire 2 by its own weight, and the hammer club falls freely.

The release cylinder 54 and the pressure reducing valve 86 are connected to a semi-brake release valve 126 to which a pilot fluid is supplied when the release control valve 90 is switched to the release position 90a. When the pilot fluid is supplied, the release position 126a connects the release cylinder 54 and the pressure reducing valve 86 to the tank 76 on the low pressure side.
And a braking position 126b that connects the release cylinder 54 and the pressure reducing valve 86 to the brake control valve 128 when the pilot fluid is not supplied.

When the excitation signal is input, the brake control valve 128 is connected to the semi-brake release valve 126 and the hydraulic pump 78.
And a braking position 128b that connects the semi-brake release valve 126 and the tank 76 when an excitation signal is not input. In the second embodiment, the release control valve 90 and the brake control valve 128 constitute a control valve.

In the second embodiment, first, in the case of hoisting, when the operating lever 82 is operated to the hoisting side without inputting the excitation signal to the semi-brake switching valve 88 and the brake control valve 128, the hoisting is performed. The pilot valve 74 is switched, and the pilot fluid is supplied to the release control valve 90 and the pilot operation switching valve 70.

Therefore, the release control valve 90 is moved to the release position 90.
a, the braking of the brake mechanism 104 is released, and the pilot fluid is supplied to the semi-brake release valve 126. The semi-brake release valve 126 is switched to the release position 126a, but the release cylinder 54 is
26, which is communicated with the tank 76 via the brake control valve 128; Therefore, in a state where the brake lever 26 is swung by the urging force of the braking spring 64, the brake drum 16
Is braked, and the second carrier 124 does not rotate.

The pilot operation switching valve 70 is in the hoisting position 7
0a, the winch drum 1 is rotated by the forward rotation of the hydraulic motor 102, and the wire 2 is wound up. When the operation lever 82 is operated to the lowering side, the pilot operation switching valve 70 is switched to the lowering position 70c, the hydraulic motor 102 rotates in the reverse direction, and the wire 2 is fed.

On the other hand, when the hammer club hung on the wire 2 is allowed to fall freely, an excitation signal is input to the brake control valve 128 to switch to the release position 128a. Thereby, the release cylinder 5 is released via the semi-brake release valve 126.
4 and the hydraulic pump 78 are communicated, and the release cylinder 54 releases the braking by swinging the brake lever 26 against the urging force of the brake spring 64.

Therefore, even when the brake mechanism 104 is in the braking state, the winch drum 1 can rotate freely, and the wire 2 is fed out by the weight of the hammer club, and the winch drum 1 rotates. When the hammer club falls to a predetermined height, an excitation signal is input to the semi-braking switching valve 88 to switch to the semi-braking position 88a.

Thus, the semi-brake cylinder 44 and the hydraulic pump 78 are connected to the brake control valve 128 and the semi-brake release valve 1.
26, the pressure reducing valve 86, and the semi-brake switching valve 88 communicate with each other, the cylinder rod 46 protrudes, and the brake lever 26 swings. As a result, when the brake drum 16 is half-braked and the hammer club digs into the ground, the winch drum 1 stops rotating due to inertia due to the semi-braking, so that the wire 2 does not fly out and the wire 2 is prevented from being turbulently wound. Is done.

Also in the case of the second embodiment, when the excitation signal is input to the semi-brake switching valve 88, the operation lever 8
2 is not braked even if it is operated.
9 can avoid problems such as heat generation due to the rotation of the winch drum 1 while being semi-braking, and the semi-braking mechanism 4
9 can be avoided.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various modes without departing from the gist of the present invention.

[0054]

As described above in detail, in the winch braking device of the present invention, when the brake drum is half-braked by the semi-braking mechanism and the hammer club digs into the ground, the winch drum stops rotating by inertia due to the semi-braking. So that
This has the effect of preventing the wire from jumping out and preventing the wire from being wound. Further, even if the pilot valve is switched while the excitation signal is input to the semi-brake switching valve,
Since the semi-braking is not performed, problems such as heat generation due to the rotation of the winch drum while the semi-braking mechanism is half-braking can be avoided, and problems due to operation errors due to the provision of the semi-braking mechanism can be avoided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a winch braking device as one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a brake mechanism and a semi-brake mechanism of the present embodiment.

FIG. 3 is a schematic configuration diagram of a winch braking device according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Winch drum 2 ... Wire 12, 102 ... Hydraulic motor 16 ... Brake drum 21 ... Clutch mechanism 26 ... Brake lever 44 ... Semi-braking cylinder 49 ... Semi-braking mechanism 54 ... Release cylinder 66, 104 ... Brake mechanism 70 ... Pilot operation switching Valve 72: Lowering pilot valve 74: Hoisting pilot valve 84: Clutch control valve 85, 126: Semi-brake release valve 88: Semi-brake switching valve 90: Release control valve 92, 128 ... Brake control valve 100: Planetary deceleration Machine 125… Clutch / brake mechanism

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B66D 5/26

Claims (2)

(57) [Claims] 1. A clutch mechanism for transmitting / disconnecting the rotation of a hydraulic motor to a winch drum in accordance with hydraulic fluid supplied thereto, and braking the rotation of the winch drum by a biasing force of a brake spring, and supplying hydraulic fluid to the winch drum. A brake mechanism that releases braking, a pilot operation switching valve that switches communication / shutoff between a hydraulic source and the hydraulic motor by supplying a pilot fluid, and a pilot valve that switches supply of the pilot fluid to the pilot operation switching valve. A winch braking device, comprising: a control valve for selectively switching communication between a hydraulic pressure source or a low pressure side and the brake mechanism and the clutch mechanism, wherein the clutch mechanism is shut off and the brake mechanism is released to allow free fall. A semi-braking mechanism for semi-braking the rotation of the winch drum with supplied hydraulic oil, A semi-brake switching valve for selectively switching communication between the semi-brake mechanism and the hydraulic oil supply side or between the semi-brake mechanism and the low-pressure side; and a supply of a pilot fluid from the pilot valve to the semi-brake switch valve and the hydraulic oil. A winch braking device, comprising: a semi-brake release valve that switches from communication with the supply side to communication with the half-brake switching valve and communication with the low-pressure side. 2. A planetary speed reducer for reducing the rotation of a hydraulic motor and transmitting the reduced speed to a winch drum, and an input member among three rotatable members of the planetary speed reducer according to supply and discharge of hydraulic oil. A brake mechanism that brakes rotation by connecting the winch drum to an output member, and a clutch / brake mechanism that brakes and releases rotation according to the supply and discharge of hydraulic oil to the remaining members; and A pilot operation switching valve for switching communication / disconnection between a hydraulic source and the hydraulic motor by supplying a fluid, a pilot valve for switching supply of the pilot fluid to the pilot operation switching valve, a hydraulic source or a low pressure side, and the brake mechanism And a control valve for selectively switching communication with the clutch / brake mechanism. A winch braking device capable of releasing a brake mechanism and free-falling, a semi-braking mechanism for semi-braking the rotation of the winch drum by supplied hydraulic oil, a semi-braking mechanism and a hydraulic oil supply side or the semi-braking A semi-brake switching valve for selectively switching communication between a mechanism and a low-pressure side; and a supply of a pilot fluid from the pilot valve, whereby the communication between the semi-brake switch valve and the hydraulic oil supply side causes the semi-brake switch valve and the low pressure A semi-brake release valve for switching to communication with the side, and a winch braking device comprising: