JPH11246187A - Braking device for winding-up winch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To let a winch be braked by leg power at the time of free falling operations, and enhance operation properties by widening a braking range when the brake is applied at the time of heavy operations. SOLUTION: In this device, hydrualic pressure P0 suppied from a pressure source 6 is decompressed down to secondary pressure P1 as specified, and the secondary pressure P1 is decompressed by a secondary pressure reducing valve 9 in such a way as to be assist pressure proportional to the pressure of the head side oil chamber 1a of a braking cylinder 1. The aforesaid assist pressure is additionally applied to the rod side oil chamber 1b of the braking cylinder 1 in such a way that the leg power of an operator can be made light, and when the pressure of the head side oil chamber 1a is equal to or greater than a specified value, the assist pressure is made equal to the secondary pressure P1 , and since no sssist pressure is increased beyond the secondary pressure, the increasing rate of braking force as leg power is increased, can thereby be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hoist winch braking device used for a crane or the like.

[0002]

2. Description of the Related Art In general, a hoisting winch mounted on a construction machine such as a crane is used for hoisting and hoisting work of a suspended load, and also for bucket work such as a clamshell. In bucket work, hoisting winches are frequently free-falled.However, in order to brake a winch during a free-fall, a large braking force that is at least twice the static load determined by the bucket weight and the like is required. Become. As shown in FIG. 5, which is a conventional brake device, the winch is braked by depressing a brake pedal as follows.

When the brake pedal P is depressed, a stroke of a brake cylinder 1 connected to the brake pedal P via a link mechanism L is performed. Road 2
The stroke of the wheel cylinder 3 communicated with the brake cylinder 1 via the stroke operation is performed. When the stroke of the wheel cylinder 3 is performed, the brake band 5 wound around the brake drum 4 is tightened, and the brake drum 4 is braked. The operating pressure of the wheel cylinder 3 is controlled by the booster 30. The booster 30 detects the pressure in the head side oil chamber 1 a of the brake cylinder 1 with a pressure sensor 31.
And the controller 32 outputs a pressure-reducing signal corresponding to the measured pressure to the pressure-reducing valve 33 for control. As a result, the assist pressure from the pressure source 6 proportional to the increase in the depression force of the brake pedal P is applied to the rod-side oil chamber 1b of the brake cylinder 1, and the load LD during the free fall is braked without strongly depressing the brake pedal P. It is possible to obtain the braking force necessary for the braking.

[0004] The pedaling force F and the braking force B of the brake pedal P
For example, Japanese Unexamined Patent Publication No. 6-100294 discloses a braking characteristic as shown in FIG. According to this, a plurality of braking characteristics C
1 and C2 are stored, and an operator appropriately selects a characteristic according to the work content from among them. As a result, for example, a heavy braking force can be obtained with a light pedaling force by selecting a characteristic C1 having a steep gradient during heavy work, and a fine brake operation can be achieved by selecting a curve C2 having a gentle slope during light work. Becomes possible.

[0005]

However, if, for example, the characteristic C1 is selected by such a brake device and a free fall operation is performed, the following problem occurs.
That is, the characteristic C1 is the braking force B with respect to the increase in the pedaling force F.
Is large, so that a large braking force can be obtained with a light pedaling force. However, a slight variation in the pedaling force F causes a large variation in the braking force B. As a result, fine brake operation becomes difficult and operability deteriorates, and if the brake pedal P is depressed too much during speed control of a bucket or the like during a free fall, a problem such as occurrence of a braking shock occurs. In addition, with the recent spread of the all-casing method, the drilling of pile holes using a hammer grab bucket is increasing, but in this case, the operability of the brake is further deteriorated because the landing state of the bucket is not visible. Against this background, there is an increasing need for a brake device that is not too sensitive to fluctuations in pedaling force with light pedaling force.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hoisting winch braking device capable of braking a hoisting winch with a light pedaling force and widening a control area at the time of heavy working to improve operability. Is to do.

[0007]

Means for Solving the Problems (1) Referring to FIGS. 1 to 3 showing one embodiment, the invention of claim 1 performs a stroke operation by the action of an operating force, and A brake cylinder 1 for outputting a braking force at a first increasing rate, a braking means 5 (FIG. 5) for braking the winch drum 4 (FIG. 5) based on the braking force output from the brake cylinder 1, and a brake cylinder 1 Control devices 7 to 9 for controlling the braking force output from the control device.
Means that the operating force acting on the brake cylinder 1 is a predetermined value Fb
When it is less than the first increasing rate (between a and b in FIG. 3), the braking force is output at the first increasing rate (between a and b in FIG. 3). The above object is achieved by outputting the braking force at a low second increase rate (between bc in FIG. 3). (2) The invention according to claim 2 is based on a brake cylinder 1 that performs a stroke operation by the action of an operating force and outputs a braking force at a first increasing rate with respect to the operating force, and a braking force output from the brake cylinder. Winch drum 4 (Fig. 5)
And a winch drum 4 based on the braking force output from the brake cylinder 1.
(FIG. 5). The control devices 7 to 9 are configured to brake the brake cylinder 1 when the operating force applied to the brake cylinder 1 is less than a first predetermined value Fb. A-
b), the braking force is output, and when the operating force becomes equal to or more than the first predetermined value Fb, the second increase rate (b- in FIG. 3) is lower than the first increase rate (a-b in FIG. 3). c), the braking force is output, and when the operating force becomes equal to or more than the second predetermined value Fc, the third increase rate (c- in FIG. 3) is higher than the second increase rate (between bc in FIG. 3). d
The above-mentioned object is achieved by outputting the braking force during the period. (3) The invention according to claim 3 is a brake cylinder 1 that performs a stroke operation by the action of an operating force, and a braking means 5 (FIG. 5) that brakes the winch drum 4 (FIG. 5) according to the stroke operation of the brake cylinder 1. And control devices 7 to 9 for applying an assist pressure to the brake cylinder 1 in order to reduce an operation force to be applied to the brake cylinder 1. The above object is achieved by controlling the rate of increase with respect to the control force to be lower than before until the operation force becomes equal to or more than the predetermined value Fb. (4) The invention of claim 4 provides a brake cylinder 1 that performs a stroke operation by the action of an operating force, and a braking means 5 (FIG. 5) that brakes the winch drum 4 (FIG. 5) according to the stroke operation of the brake cylinder 1. And control devices 7 to 9 for applying an assist pressure to the brake cylinder 1 in order to reduce an operation force to be applied to the brake cylinder 1. 3 until the operating force reaches the first predetermined value Fb.
A-b), and when the operating force exceeds the first predetermined value Fb, the second increase rate (between bc in FIG. 3) is lower than the first increase rate (between a and b in FIG. 3). ), And when the operating force is equal to or greater than the second predetermined value Fc, control is performed at a third increase rate (between cd in FIG. 3) higher than the second increase rate (between bc in FIG. 3). Achieves the above object. (5) The invention of claim 5 provides a brake cylinder 1 that is stroke-operated by an operation by an operator, and a winch drum 4 that is operated in accordance with the stroke operation of the brake cylinder 1
A brake band 5 (FIG. 5) for braking the brake cylinder (FIG. 5) and a brake cylinder 1 for reducing the operation force by the operator.
And a booster 10 for increasing the assist pressure. And the booster 10
Comprises valve devices 7 to 9 for changing the assist pressure in accordance with the operation force F of the brake cylinder 1, and the valve devices 7 to 9
An output characteristic in which the assist pressure increases with an increase in the operating force F, and when the operating force F becomes equal to or more than the first predetermined value Fb, the ratio of the increase in the assist pressure to the increase in the operating force F becomes smaller than before. The above object is achieved by having (6) According to the invention of claim 6, the valve devices 7 to 9 reduce the primary pressure to a predetermined secondary pressure by the first pressure reducing valve 8 and the second pressure reducing the secondary pressure to the assist pressure. The pressure reducing characteristic of the second pressure reducing valve 9 is set so that the assist pressure and the secondary pressure become substantially equal when the operating force F becomes equal to or more than the first predetermined value Fb. (7) According to a seventh aspect of the present invention, as shown in FIG. 4, the booster 20 is controlled by a detecting means 21 for detecting an operating force F and an assist pressure is calculated in accordance with a detection result of the detecting means 21. The output characteristic of the valve device 23 is controlled by the control means 22. (8) According to the invention of claim 8, the output characteristics of the valve devices 7 to 9 are set such that, when the operating force F becomes equal to or more than a second predetermined value Fc larger than the first predetermined value Fb, the assist pressure with respect to the increase of the operating force F The output characteristic is such that the rate of increase of P92 is greater than between the first predetermined value Fb and the second predetermined value Fc.

[0008] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a diagram showing a first embodiment of a hoist winch braking device according to the present invention. Although FIG. 1 mainly shows the booster 10, other configurations other than those shown in FIG. 1 are the same as those in FIG. The same reference numerals are given.

As shown in FIG. 1, the booster 10 has a switching valve 7, a first pressure reducing valve 8, and a second pressure reducing valve 9. The switching valve 7 is a three-port two-position switching valve for pilot command. The primary port of the switching valve 7 is connected to the head-side oil chamber 1a of the brake cylinder 1 via a pipe line 11, and the secondary port is connected to the tank 12 Pilot port 8 of pressure reducing valve 8
and p. The pilot port 7p of the switching valve 7 is connected to the head-side oil chamber 1a through the pipelines 11 and 13.
When the head-side oil chamber 1a becomes equal to or higher than a predetermined pressure Pa set by the spring 7s, the position of the switching valve 7 becomes (a).
The pilot pressure Pb is supplied to the pilot port 8 p of the first pressure reducing valve 8.

The primary pressure side of the first pressure reducing valve 8 is connected to the hydraulic pressure source 6 for supplying oil at a constant pressure P0, and the secondary pressure P82 side is connected to the second pressure source.
Of the switching valve 9 is connected to the primary side port. When the pilot port 8p is connected to the tank as shown in FIG. 1, the first pressure reducing valve 8 is a pressure reducing valve 8 dependent on a spring 8s, and reduces the primary pressure P0 to a predetermined secondary pressure P82. .
When the pilot pressure Pb is connected to the head side oil chamber 1a of the brake cylinder 1, the secondary pressure P82 is not reduced.
Becomes the pump pressure P0. That is, the first pressure reducing valve 8
It functions as a pressure reducing valve only before the pilot pressure Pb from the switching valve 7 is introduced. The dashed line in FIG. 2 shows the output characteristic of the first pressure reducing valve 8, and the pilot pressure Pb is introduced from the switching valve 7 by the pedaling force Fc, and the secondary pressure P82 becomes the pump pressure P0.

The second pressure reducing valve 9 is a proportional pressure reducing valve that reduces the pressure in proportion to the pressure applied to the pilot port 9p. The primary pressure side is connected to the secondary pressure side of the first pressure reducing valve 8 and the tank 14, respectively. The secondary pressure P92 is connected to the rod-side oil chamber 1b of the brake cylinder 1. The pilot port 9p of the second pressure reducing valve 9 is connected to the head-side oil chamber 1a of the brake cylinder 1 via the pipelines 11, 15, and the pressure of the head-side oil chamber 1a becomes equal to or higher than a predetermined pressure Pc set by the spring 9s. Then, the position of the second pressure reducing valve 9 is switched from (c) to (d). When the position of the second pressure reducing valve 9 is switched to (d), the pressure in the second pressure reducing valve 9 is reduced in proportion to the pressure of the head side oil chamber 1a (hereinafter referred to as a booster pressure) due to its pressure reducing characteristic. The rod side oil chamber 1b is pressurized by the assist pressure after the pressure reduction. The solid line in FIG. 2 shows the output characteristics of the second pressure reducing valve 9,
The secondary pressure P92, that is, the assist pressure P92, increases proportionally after the pedaling force Fa to Fb and the pedaling force Fc.

FIG. 3 is a diagram showing the relationship between the depressing force F and the braking force B when the brake pedal is depressed, and shows the braking characteristics of the hoisting winch braking device according to the present embodiment. The operation of the hoisting winch braking device according to the first embodiment will be described below with reference to FIG.

(1) Depressing force 0-Fa When the brake pedal P is depressed, the booster pressure, which is the pressure of the head-side oil chamber 1a, increases as the depressing force F increases, and the braking force B decreases as the booster pressure increases. To increase. The characteristic L1 in FIG. 2 is a brake characteristic when the booster 10 does not operate. Between 0 and a, the brake B is output only by the depression force F of the brake pedal P without receiving assistance from the booster 10. You.

(2) Between the pedaling force Fa and Fb When the pedaling force rises to Fa and reaches point a, the head side oil chamber 1
The pressure a becomes the pressure Pc set by the spring 9s of the second pressure reducing valve 9, and the second pressure reducing valve 9 is switched from (C) to (D). As a result, the second pressure reducing valve 9 outputs a predetermined secondary pressure P output from the first pressure reducing valve 8 as shown in FIG.
1 is input as the primary pressure, and the pressure proportional to the pilot pressure to the pilot port 9p is output as the secondary pressure P92. The secondary pressure P92 output from the second pressure reducing valve 9 is applied to the rod side oil chamber 1b of the brake cylinder 1 by the assist pressure P92.
Pressurized as As shown in FIG. 2, the assist pressure P92 increases in proportion to the increase in the booster pressure between the pedaling forces Fa and Fb, that is, increases in the pedaling force F. Therefore, between the points a and b, the assist pressure P92 is added to the characteristic L1. As shown by the characteristic L2, the braking force B increases steeply.

(3) Tread Force Fb-Fc When the tread force increases to Fb, the assist pressure P92 becomes equal to the secondary pressure P1 of the first pressure reducing valve 8 as shown in FIG. 2, and the assist pressure P92 further increases. It is constant up to the pedaling force Fc. For this reason, the booster pressure increases only in the amount of increase in the pedaling force F between bc in FIG.
A characteristic L2 is obtained by shifting the characteristic L1 upward by the secondary pressure P1 of the first pressure reducing valve 8 with the same gradient as the characteristic L1 which is the braking characteristic of only the pedaling force F. By setting the braking force Bx required for braking during winch free fall between bc, the pedaling force Fx for obtaining the braking force BX can be set in a wide range between Fb and Fc. Can be
Fine adjustment of the braking operation becomes possible.

(4) Between the pedaling force Fc and Fd When the pedaling force increases to Fc and reaches the point c, the booster pressure becomes the pressure Pa set by the spring 7s of the switching valve 7, and the position of the switching valve 7 is ) To (b). When the switching valve 7 is switched to the (B) position, the first pressure reducing valve 8
The pilot pressure Pb from the head side oil chamber 1a is supplied to the pilot port 8p, and the first pressure reducing valve 8 does not perform the pressure reducing function, and the secondary pressure P82 of the first pressure reducing valve 8 is reduced as shown in FIG.
, The pump pressure becomes P0. Since the booster pressure fed to the pilot port 9p of the second pressure reducing valve 9 has already increased with the increase in the pedaling force F between the points b and c,
In the second pressure reducing valve 9, pressure reducing control corresponding to the booster pressure at the point c is performed, and the assist pressure P92 increases from P1 in FIG. 2 to P2. Therefore, as shown in FIG. 3, the braking force increases between cd and d without increasing the pedaling force. The point d in this case is located on the extension of the characteristic L2 determined from the output characteristic of the second pressure reducing valve 9.

(5) Between the pedaling force Fd and Fe After point d, the assist pressure P92 increases in proportion to the increase in the booster pressure with the increase in the pedaling force F, as in the case between the points a and b. Therefore, the gradient between d and e is the same as the gradient between a and b. The braking force Be and the pedaling force F at the point e are
e is the required braking force and the maximum pedaling force specified by the crane structural standard.

As described above, according to the first embodiment, the switching valve 7, the first pressure reducing valve 8, and the second pressure reducing valve 9 of the booster 10 are provided, and the pressure reducing characteristic of the first pressure reducing valve 8 is provided. Is controlled to control the assist pressure P92 supplied from the second pressure reducing valve 9, so that the rate of increase in the braking force B between the predetermined pedaling forces Fb and Fc can be reduced. As a result, even in the case of free fall work during heavy work,
The braking of the hoisting winch can be performed with a light pedaling force, and the control area of the pedaling force F during braking can be widened to reduce a braking shock.

Second Embodiment Next, a description will be given of a hoist winch braking device according to a second embodiment of the present invention. FIG. 4 is a view showing a second embodiment of a braking device for a hoisting winch. Although FIG. 4 mainly shows the booster 20, the configuration other than the booster is the same as that of FIG. 5 and the description thereof is omitted, and the same parts as those of FIG. 5 are the same. The differences will be mainly described with reference numerals.

As shown in FIG. 4, the booster 20 according to the second embodiment has a pressure gauge 21, a controller 22, and an electromagnetic proportional pressure reducing valve 23. The booster pressure of the brake cylinder 1 is detected by a pressure gauge 21 connected to the pipe 2, and the detected value is input to the controller 22 as an input signal. The controller 22 calculates an output value corresponding to an input signal from the pressure gauge, and outputs the output value as an output signal to the pilot port 23 of the electromagnetic proportional pressure reducing valve 23.
It is output to the electro-hydraulic converter for adjusting the pressure of p. Electromagnetic proportional pressure reducing valve 2 according to an output signal from controller 22
3 is controlled, the primary pressure P0 pressure-fed from the hydraulic pump 6 is set to an assist pressure P23 according to the pressure reduction characteristic, and is applied to the rod-side oil chamber 1b of the brake cylinder 1.

In the second embodiment, a predetermined braking characteristic is stored in the controller 22 in advance, and the relationship between the pedaling force F and the braking force B is the same as the braking characteristic.
An output signal output from the controller 22 is controlled. The controller 22 stores a plurality of braking characteristics having different settings so as to be suitable for a work state such as heavy work or light work. In this case, as a braking characteristic suitable for heavy work, for example, a characteristic similar to that of FIG. 3 in the first embodiment is stored, and as a braking characteristic suitable for light work, for example, a downward direction between bc in FIG. The shifted characteristics are stored. Then, at the time of work, one of the plurality of braking characteristics is selected.

As described above, according to the second embodiment, the booster 20 is provided with the controller 22 and the electromagnetic proportional pressure reducing valve 23 so that the electromagnetic proportional pressure reducing valve 23 has a predetermined braking characteristic stored in the controller 22. Since the decompression characteristic of 23 is controlled, the gradient of the braking characteristic is reduced similarly to the range between b and c in FIG. 3, so that the control region at the time of braking can be widened and operability is improved. Further, by changing the setting of the controller 22, it is possible to easily provide an arbitrary braking characteristic according to the work state, and operability is always improved regardless of the work state.

In the first embodiment, the springs 7s to 9s of the switching valve 7, the first pressure reducing valve 8, and the second pressure reducing valve 9 are used.
By changing the setting, the brake characteristics in FIG. 3 can be changed as appropriate. In this case, the spring 9 of the second pressure reducing valve 9
The point a, which is the assist start point, is set by setting s, the point b, at which the assist pressure P92 is constant, is set by setting the spring 8s of the first pressure reducing valve 8, and the assist pressure P92 is set again by setting the spring 7s of the switching valve 7. The point c, which is a point to be raised, can be changed.

As described above, the brake characteristics in the above-described embodiment include the switching valve 7, the first pressure reducing valve 8, and the second pressure reducing valve 9.
And can be freely changed by the setting of the controller 22 and is not limited to the brake characteristics of FIG.
In addition, the first pressure reducing valve 8 in the first embodiment may be a proportional pressure reducing valve, or may be an electromagnetic pressure reducing valve as in the second embodiment. Further, in the second embodiment, the brake characteristics suitable for a plurality of work states are stored in the controller 22 in advance. May be selected. Furthermore, instead of detecting the booster pressure by the pressure gauge 21,
The depression force F of the brake pedal P may be directly detected by a load cell or the like, and the value may be input to the controller 22.

As described above, the present invention relates to a method of increasing the braking force with respect to an increase in the pedaling force, wherein the braking force is gradually increased when the pedaling force exceeds a predetermined value. This is, as described above, valves 7-
The present invention is not limited to the embodiment using 9, 23, but can be implemented in various forms. For example, the switching valve 7, the first pressure reducing valve 8, and the second pressure reducing valve 9 in FIG. 1 are omitted, the operation amount of the pedal P is electrically detected, and the pressure source 6 is configured as a variable displacement hydraulic pump. May be. With such a configuration, the tilt angle of the hydraulic pump is controlled in accordance with the operation amount of the pedal P, and the supply amount of the hydraulic oil from the hydraulic pump to the brake cylinder 1 is adjusted to increase the braking force. The ratio can be arbitrarily changed.

In the correspondence between the above embodiment and the claims, the brake band 5 serves as a braking means, and the switching valve 7, the first pressure reducing valve 8 and the second pressure reducing valve 9, or the pressure gauge 21 and the controller 22. The electromagnetic proportional pressure reducing valve 23 and the control device
The switching valve 7, the first pressure reducing valve 8 and the second pressure reducing valve 9 or the electromagnetic pressure reducing valve 23 operate the valve device, the pedaling force Fb becomes the first predetermined value,
The pressure gauge 21 constitutes a detecting means, the controller 22 constitutes a control means, and the pedaling force Fc constitutes a second predetermined value.

[0028]

As described above in detail, according to the present invention, when the operating force acting on the brake cylinder exceeds a predetermined value, the rate of increase of the braking force with respect to the operating force is made smaller than before. Since it is made small, the control area at the time of braking can be widened, and the operability of the winch is improved. According to the third to fifth aspects of the present invention, since the braking device exerts the assist pressure, the pedaling force during braking can be reduced, and the operability is further improved. Further, according to the invention of claim 6, since the operating force is electrically detected and the output characteristic of the valve device is controlled by the control means, the setting of the control means is easily changed by changing the setting of the control means. Output characteristics can be changed. Furthermore,
According to the second, fourth and seventh aspects of the present invention, the operation force is further increased by the second force.
Is greater than the predetermined value, the rate of increase of the braking force with respect to the operating force is increased, so that the required braking force and the maximum pedaling force defined by the crane structural standard can be easily obtained.

[Brief description of the drawings]

FIG. 1 shows a hoisting winch braking device according to a first embodiment.

FIG. 2 is a diagram showing output characteristics of a first pressure reducing valve and a second pressure reducing valve of the hoisting winch braking device according to the first embodiment.

FIG. 3 is a diagram showing brake characteristics when a hoist winch braking device according to the embodiment is operated.

FIG. 4 shows a hoisting winch braking device according to a second embodiment.

FIG. 5 shows a conventional winch braking device for a hoisting winch.

FIG. 6 is a diagram showing brake characteristics when a hoist winch braking device according to the related art is operated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake cylinder 4 Winch drum 5 Brake band 7 Switching valve 8 1st pressure reducing valve 9 2nd pressure reducing valve 10, 20 Booster 21 Pressure gauge 22 Controller 23 Electromagnetic pressure reducing valve

Claims (8)

[Claims] 1. A brake cylinder that performs a stroke operation by the action of an operating force and outputs a braking force at a first increasing rate with respect to the operating force, and a winch drum based on the braking force output from the brake cylinder. Braking means for braking, and a control device for controlling a braking force output from the brake cylinder, wherein the control device is configured to control the first increase rate when an operating force acting on the brake cylinder is less than a predetermined value. And outputting a braking force at a second increasing rate lower than the first increasing rate when the operating force is equal to or greater than the predetermined value. 2. A brake cylinder that operates in a stroke by the action of an operating force and outputs a braking force at a first increasing rate with respect to the operating force, and a winch drum based on the braking force output from the brake cylinder. Braking means for braking; and a control device for controlling a braking force output from the brake cylinder, wherein the control device is configured to control the first force when the operating force acting on the brake cylinder is less than a first predetermined value. And outputs a braking force at a second increasing rate lower than the first increasing rate when the operating force becomes equal to or more than the first predetermined value, and outputs the braking force at a second increasing rate lower than the first increasing rate. A braking force is output at a third increase rate higher than the second increase rate when the predetermined value is equal to or more than a predetermined value. A brake cylinder for performing a stroke operation by the action of an operation force; a braking means for braking a winch drum according to a stroke operation of the brake cylinder; and a brake for reducing an operation force applied to the brake cylinder. A control device for applying an assist pressure to the cylinder, wherein the control device lowers the rate of increase of the assist pressure applied to the brake cylinder with respect to the operation force when the operation force is equal to or more than a predetermined value. Control device for a hoisting winch. 4. A brake cylinder for performing a stroke operation by the action of an operation force, a braking means for braking a winch drum according to a stroke operation of the brake cylinder, and the brake for reducing an operation force applied to the brake cylinder. A control device for applying an assist pressure to the cylinder, wherein the control device determines an increasing rate of the assist pressure applied to the brake cylinder with respect to the operating force until the operating force reaches a first predetermined value. 1, when the operating force is equal to or more than a first predetermined value, the second increasing rate is lower than the first increasing rate, and when the operating force is equal to or more than a second predetermined value, the second increasing rate is set. A hoisting winch braking device, wherein the hoisting winch is controlled to a third increasing rate higher than the increasing rate. 5. A brake cylinder which operates in a stroke by an operation of an operator, a brake band which brakes a winch drum in accordance with the operation of the brake cylinder, and a brake cylinder which reduces an operation force by the operator. A hoisting winch braking device comprising: a booster that pressurizes an assist pressure; wherein the booster includes a valve device that changes the assist pressure in accordance with an operation force of the brake cylinder. When the assist pressure increases with an increase in the operating force and the operating force becomes equal to or more than a first predetermined value, an output such that the ratio of the increase in the assist pressure to the increase in the operating force becomes smaller than before. A hoisting winch braking device having characteristics. 6. The valve device has a first pressure reducing valve that reduces a primary pressure to a predetermined secondary pressure, and a second pressure reducing valve that reduces the secondary pressure to the assist pressure. The pressure reducing characteristic of the second pressure reducing valve is set such that when the operating force is equal to or greater than the first predetermined value, the assist pressure and the secondary pressure are substantially equal. The hoisting winch braking device as described in the above. 7. The booster includes a detecting means for detecting the operating force, and a control means for calculating the assist pressure in accordance with a detection result of the detecting means. 6. The hoisting winch braking device according to claim 5, wherein an output characteristic of the hoisting winch is controlled. 8. The valve device, when the operating force is equal to or greater than a second predetermined value larger than the first predetermined value, a ratio of an increase in the assist pressure to an increase in the operating force is equal to the first predetermined value. 8. An output characteristic having a value larger than a value between a predetermined value and the second predetermined value.
The hoisting winch braking device according to claim 1.