EP0819646A1 - Method and system for controlling the speed of a winch - Google Patents
Method and system for controlling the speed of a winch Download PDFInfo
- Publication number
- EP0819646A1 EP0819646A1 EP95910783A EP95910783A EP0819646A1 EP 0819646 A1 EP0819646 A1 EP 0819646A1 EP 95910783 A EP95910783 A EP 95910783A EP 95910783 A EP95910783 A EP 95910783A EP 0819646 A1 EP0819646 A1 EP 0819646A1
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- EP
- European Patent Office
- Prior art keywords
- speed
- winch
- pilot
- valve
- pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66D—CAPSTANS; WINCHES; TACKLES, e.g. PULLEY BLOCKS; HOISTS
- B66D1/00—Rope, cable, or chain winding mechanisms; Capstans
- B66D1/28—Other constructional details
- B66D1/40—Control devices
- B66D1/42—Control devices non-automatic
- B66D1/44—Control devices non-automatic pneumatic of hydraulic
Definitions
- the present invention relates to a method and a system for controlling the speed of a winch, and more particularly, to a method and a system for controlling the speed of a winch which drives a winch drum by oil pressure.
- winch devices for use in a crane, etc. have been designed to consist of, for example, a main winding winch 50 and an auxiliary winding winch 60, as shown in Fig. 5.
- the main winding winch 50 driven by oil pressure is comprised of a hydraulic motor 51, a reduction gear 52 driven by the hydraulic motor 51, an output axis 52a of the reduction gear 52, and a clutch 53 provided on a driving shaft 55 fixed to a main drum 56.
- a brake drum 54a is fixed to a flange of the main drum 56, and a band brake 54 is wound around the brake drum 54a.
- the rotation of the hydraulic motor 51 is decelerated by the reduction gear 52 and transferred to the output shaft 52a, and when the clutch 53 is engaged, the rotation is transferred to the main drum 56 through the driving shaft 55.
- the rotation of the main drum 56 can be controlled in response to the rotation of the hydraulic motor 51.
- a light load such as a hook
- an impactive force of a hammer due to a free fall such as a piling operation in construction work
- the winch is used in a free fall state. In these cases, disengagement of the clutch 53 puts the suspended load of the main winding winch 50 into a free fall state.
- the brake 54 In the case of controlling the falling speed, the brake 54 is pressed against the brake drum 54a, and braking force is adjusted by a degree of pressing. Therefore, when the winch is used in the free fall state, the light load can be lowered in a short period of time, and a large impactive force by a heavy article such as a hammer can be obtained.
- the arrangement and operation of the auxiliary winding winch 60 are the same as those of the main winding winch 50, and an explanation thereof is omitted.
- the present invention has been made to solve the problems of the prior art, and its object is to provide a method of and a system for controlling the speed of a winch which connects the driving device of a winch drum to the winch drum at all times, thereby eliminating a free fall state, and improving safety and operability for the operator.
- a method of controlling the speed of a winch which is operated by controlling a rotation of a winch drum with an operating lever, wherein the rotation speed of the winch drum is substantially a direct and exclusive speed with respect to the stroke of an operating lever until a predetermined stroke of the operating lever, while the speed is a different speed with respect to the same stroke of the operating lever in response to a speed mode selected from a plurality of speed modes at strokes over the predetermined stroke.
- the selected speed mode may be switched to another speed mode at the stroke in the middle of the strokes over the predetermined stroke.
- the speed mode may be switched, when switching from a low-speed speed mode to a high-speed speed mode, under previously set conditions.
- the winch drum rotation speed until the predetermined stroke may gradually increase in response to an increase in the stroke of the operating lever, and may be the same among the plurality of speed modes.
- the winch drum rotation speed until the predetermined stroke is equal in each speed mode so that the operator's sense of operation at the beginning of the operation is common, thus offering good operability.
- the selection of, for example, a high-speed speed mode increases the rotation speed and improves working efficiency.
- a reduction in the rotation speed at the beginning of the operation improves fine operability.
- different speed modes can be selected as needed, thus offering high operability.
- a first aspect of a system for controlling the speed of a winch comprises a pilot pipe for connecting a regulator for supplying control pressure corresponding to pilot pressure to a control cylinder of a variable hydraulic motor and a pilot valve for supplying pilot pressure to a pilot-type operating valve, and a mode switching open/close valve for communicating or shutting off the pilot pipe.
- the regulator may be provided with a setting means, and the setting means may stop an operation of the regulator until a predetermined pilot pressure, and may reduce a specific capacity of the variable hydraulic motor in response to control pressure of the regulator at pilot pressures over the predetermined pilot pressure.
- the mode switching open/close valve may be a solenoid-operated mode switching open/close valve having a solenoid, and an operating lever knob of the pilot valve may be provided with a switch so as to output an electric signal from the switch to the solenoid.
- the control pressure pipe for connecting the regulator and the control cylinder may be provided with a restriction device.
- the system may comprise a capacity control means for the variable hydraulic motor, a connecting means for connecting the capacity control means and a piston rod of the control cylinder, and a capacity setting means including a capacity setting member and a stopper, wherein the capacity setting member is fixed to any one of the capacity control means, the piston rod, and the connecting means so as to set a minimum capacity of the variable hydraulic motor, and wherein the stopper restricts or releases the movement of the capacity setting member.
- the winch drum rotation speed is controlled by the pilot-type operating valve and the variable hydraulic motor of which the specific capacity is reduced by the control cylinder.
- the regulator and the pilot valve are shut off, the regulator is not operated, so that the control pressure of the regulator is not supplied to the control cylinder of the variable hydraulic motor. Therefore, the winch drum rotation speed is controlled by only the pilot-type operating valve which is operated in response to pilot pressure.
- control pressure of the regulator is not supplied to the control cylinder until a predetermined stroke of the operating lever, so that the winch drum rotation speed is controlled by the pilot-type operating valve.
- the specific capacity of the variable hydraulic motor is reduced by the control pressure of the regulator responsive to the pilot pressure. Therefore, the winch drum rotation speed is controlled by the reduced specific capacity and the pilot-type operating valve. At this time, if the mode switching open/close valve is shut off, the winch drum rotation speed is controlled by only the pilot-type operating valve, so that the speed reduces with respect to the same stroke of the operating lever.
- the winch drum rotation speed is substantially directly and exclusively determined with respect to the stroke of the operating lever until the predetermined stroke regardless of communication and shut-off of the mode switching open/close valve.
- the winch drum rotation speed becomes the speed corresponding to each mode even at the same stroke of the operating lever.
- the speed mode can be switched by the switch while controlling the winch drum rotation speed by the operating lever.
- the specific capacity of the variable hydraulic motor does not change abruptly, so that abrupt changes in the winch drum rotation speed can be prevented, thereby improving safety and durability of the device.
- the variable hydraulic motor has a predetermined minimum specific capacity when the stopper restricts the movement of the capacity setting member. On the other hand, when the movement restriction is released, the specific capacity of the variable hydraulic motor can be reduced to 0, and the winch can be operated into a free fall state.
- a second aspect of the system for controlling the speed of a winch is characterized in that a selective valve is attached, and that the selective valve selects higher pressure of predetermined pressure of a pressure source and driving pressure of the variable hydraulic motor so as to supply the pressure as the main pressure of the regulator.
- the control pressure supplied to the control cylinder of the variable hydraulic motor employs a predetermined pressure of the pressure source as the main pressure while the driving pressure of the variable hydraulic motor is low.
- the driving pressure is supplied as the main pressure of the regulator to the control cylinder of the variable hydraulic motor, so that the specific capacity of the variable hydraulic motor can reliably be controlled.
- a third aspect of the system for controlling the speed of a winch is characterized in that a directional control valve is provided between a relief valve for controlling a return oil pressure of the hydraulic motor at the time of lowering the winch drum and a negative brake provided on a connected portion of the hydraulic motor and the winch drum, and that the directional control valve passes therethrough or shuts off function releasing pilot pressure for the relief valve, and opening pilot pressure for the negative brake.
- the directional control valve when the directional control valve is switched to a passing position, the function releasing pilot pressure and the opening pilot pressure are supplied, and the winch drum can be freely rotated, so that maintenance and examination of the winch can be easily effected.
- numeral 1 denotes a winch pump for driving a winch
- 3 denotes a pressure compensating valve
- 4 denotes a pilot-type operating valve
- 5 denotes an operating lever for operating the winch
- 5a denotes a pilot valve for supplying pilot pressure to the pilot-type operating valve 4, etc.
- 5b denotes a high-speed mode switching button.
- Numeral 6 denotes a hydraulic motor (a variable hydraulic motor is used in this embodiment), 6b denotes a swash plate (a capacity control means) provided in the hydraulic motor 6, 7a denotes a check valve, 7b denotes a relief valve, 8 denotes a control pump (pressure source) for supplying control pressure of this speed control system, 9 denotes a directional control valve for supplying the control pressure of the motor, 9a is a directional control valve for supplying control pressure of an auxiliary winding winch, 11 denotes a directional control valve for pilot main pressure of the pilot pump 8 which is held in constant pressure by the relief valve 10, 12 denotes a negative brake contained in the hydraulic motor 6, and 13 denotes a winch drum driven by the hydraulic motor 6.
- numeral 18 denotes a high-speed mode switching valve for switching pilot pressure of the pilot valve 5a output through a shuttle valve 23
- 19 denotes a regulator for controlling capacity of the hydraulic motor 6 with a difference between the pilot pressure supplied through the high-speed mode switching valve 18 and spring force of a setting spring (setting means) 19a
- 20 denotes a control cylinder of the hydraulic motor 6
- 20a denotes a link (linking means) for linking between a piston rod of the control cylinder 20 and the swash plate 6b
- 21 denotes a restrictor (restriction device) provided on a control pressure pipe to the control cylinder 20
- 22 denotes a relief valve provided on a driving main pipe of the hydraulic motor 6.
- numeral 24 denotes a controller
- 24a denotes an AND circuit which constitutes the controller 24.
- the AND circuit 24 outputs an excitation signal to a solenoid 18a of the high-speed mode switching valve 18 when predetermined conditions, for example, in the case of this embodiment, (i) an ON signal of the high-speed mode switching button 5b, (ii) a pilot pressure signal Pd of a lowering side of the pilot valve 5, and (iii) a predetermined rope tension signal Ts are inputted at the same time.
- predetermined conditions for example, in the case of this embodiment, (i) an ON signal of the high-speed mode switching button 5b, (ii) a pilot pressure signal Pd of a lowering side of the pilot valve 5, and (iii) a predetermined rope tension signal Ts are inputted at the same time.
- condition (ii) is set to avoid a problem which arises in the case of speeding up a hoisting operation, such as irregular winding of a rope due to deterioration of rope winding properties over the drum, or the generation of excessive shock due to a sudden stop at the time of excessively hoisting a hook.
- the condition (iii) is set to avoid falling of a suspended load even if it exceeds the holding capacity of the hydraulic motor. Moreover, since the above (iii) hardly hoists and lowers a heavy load at a high speed during a normal operation, it has an object to prevent an excessive load on the entire device by restricting a high-speed operable load to a light load below a predetermined amount, and to enhance safety.
- the rope tension is an input signal corresponding to the suspended load, and a load which directly acts on the winch device from the outside becomes the input signal.
- the rope tension can be obtained, for example, by dividing the suspended load obtained through an overload protection device by the previously input number of falls of the rope over the hook.
- numeral 27 denotes a low-pressure relief valve provided on a winch-lowering pipe
- 28 denotes a tank
- 30 denotes a drum-free switch
- 31 denotes a drum-free directional control valve
- 32 denotes a restrictor provided on a pipe which supplies a pilot main pressure of the pilot pump 8 to the negative brake 12 through the brake valve 11
- 33 denotes a solenoid open/close valve
- 34 denotes a capacity setting means including a capacity setting cylinder 34a and a capacity setting member 34b fixed to a piston rod of the control cylinder 20, and 35a, 35b, and 35c denote check valves.
- the speed mode of this embodiment includes the following four modes: a Hi/rating mode and a Hi/high-speed mode in a high-speed engine, and a Lo/rating mode and a Lo/high-speed mode in a low-speed engine.
- the flow rate responsive to an operating amount of the pilot-type operating valve 4 is supplied from the winch pump 1 and a boom pump (not shown) to the hydraulic motor 6 and, at the same time, the directional control valve 9 is switched to a position b by load pressure taken out of the pilot-type operating valve 4, whereby control pressure of the pilot pump 8 is supplied to the brake valve 11 through the position b of the directional control valve 9 and the restrictor 32, so that braking of the negative brake 12 is released.
- This release causes the winch drum 13 to be rotated at rotation speed responsive to the operating amount of the operating lever 5.
- the drum-free directional control valve 31 is changed into the position b, and the brake valve 11 is changed into the position a, whereby the negative brake 12 is opened by control pressure of the control pump 8, and the control pressure of the control pump 8 is supplied to the relief valve 7b, so that the winch drum 13 can rotate freely also to the lowering side.
- an electric signal of a non-illustrated switch is first outputted to a solenoid of the brake valve 11, and the brake valve 11 is changed into the position a so as to open the negative brake 12.
- the electric signal is also outputted to a solenoid of the solenoid open/close valve 33, and the solenoid open/close valve 33 is changed into the position b, whereby the control pressure of the control pump 8 is supplied to a rod chamber of the capacity setting cylinder 34a and the control cylinder 20. This causes a rod (stopper) of the capacity setting cylinder 34a to constrict, thereby releasing movement restrictions of the capacity setting member 34b.
- the released capacity setting member 34b moves the swash plate 6b through the piston rod of the control cylinder 20 and the link 20a to set the capacity of the hydraulic motor 6 to 0 cc/rev. Therefore, when the lowering speed faster than that of the Hi/high-speed mode is required, setting the capacity of the hydraulic motor 6 to 0cc/rev as described above enables a free fall operation even if the clutch is omitted.
- Fig. 2 shows four kinds of speed modes in this embodiment.
- the speed mode is represented by two states: a Hi state in which the engine speed is equivalent to a high-idle rotating state, and a Lo state in which the engine speed is equivalent to a low-idle rotation state.
- the speed mode may naturally be set to a state equivalent to a middle of them.
- the specific capacity of the hydraulic motor is changed from V to 0.5 V in the high-speed mode, a minimum specific capacity is not limited to 0.5 V. Therefore, it is a matter of course that the specific capacity of the hydraulic motor can suitably be selected, and that the above high-speed mode is pluralized by setting the minimum specific capacity in the plural.
- Fig. 3 is an illustration of the system for controlling the speed of a winch according to the above-described arrangements. Each mode at the time of lowering by the main winding winch shown in the right of Fig. 3 will be described with reference to the operating conditions of Fig. 2, and Fig. 1.
- a section between lever strokes N and S1 is a dead zone due to leakage oil of hydraulic equipment such as the hydraulic pump 1 and the hydraulic motor 6, and the winch drum 13 does not rotate.
- the winch drum 13 in the section between the lever strokes N and S1 does not rotate in any mode of the Hi/high-speed mode, Lo/rating mode, and Lo/high-speed mode to be described later.
- the drum rotation speed between lever strokes S1 and S6 is increased up to N6 by a flow rate determined by opening properties of the pilot-type operating valve 4.
- the drum rotation speed is illustrated taking the rated rotation speed N6 as 100 %.
- pilot pressure of the pilot valve 5a is supplied to the capacity controlling regulator 19 in response to the lever stroke of the operating lever 5.
- pressing force due to the pilot pressure is set smaller than spring force of the setting spring 19a between the lever strokes S1 and S4, so that the capacity controlling regulator 19 remains in the position b.
- the drum rotation speed between the lever strokes S1 and S4 is increased up to N4 by opening properties of the pilot-type operating valve 4.
- the drum rotation speed between the lever strokes S1 and S4 is the same as that in the Hi/rating mode.
- the pressing force of the capacity controlling regulator 19 becomes larger than the spring force of the setting spring 19a, so that the capacity controlling regulator 19 is started to operate in the a direction.
- the specific capacity of the hydraulic motor 6 is decreased from V to 0.5 V by the pilot pressure responsive to the lever stroke between the lever strokes S4 and S5, and the rotation speed of the winch drum 13 is increased up to N7 in response to an increase in flow rate by the pilot-type operating valve 4. That is, the winch drum rotation speed between S4 and S5 becomes twice the speed of the Hi/rating mode.
- the specific capacity of the hydraulic motor 6 is constant between the lever strokes S5 and S6, and the flow rate determined by opening properties of the pilot-type operating valve 4 due to the lever stroke slightly increases, so that the winch drum rotation speed remains constant at N7.
- the higher oil pressure of the higher driving pressure of the hydraulic motor 6 selected by the check valves 35a and 35b, and discharge pressure of the control pump 8 which is held at a predetermined pressure by the relief valve 10 is selected by the check valve 35c (selective valve).
- the main pressure is reduced in response to the operating amount of the regulator 19 responsive to the lever stroke, and is supplied to the control cylinder 20 of the hydraulic motor 6. Therefore, the control pressure supplied to the control cylinder 20 is, while the driving pressure of the hydraulic motor 6 is low, secured by the discharge pressure of the control pump 8 held at a predetermined pressure.
- the driving pressure of the hydraulic motor 6 increases, the driving pressure is supplied to the control cylinder 20 as the main pressure of the capacity controlling regulator 19, so that the capacity of the hydraulic motor 6 can reliably be controlled.
- the winch rotation speed between the lever strokes S1 and S3 is increased up to N3 by opening properties of the pilot-type operating valve 4.
- the winch drum rotation speed between the lever strokes S3 and S6 remains constant at N3 because the flow rate flowing into the pilot-type operating valve 4 is a predetermined maximum flow rate (constant) corresponding to the Lo rating mode.
- the winch drum rotation speed is increased up to N3 by the pilot-type operating valve 4 between the lever strokes S1 and S3, and is constant at N3 between the lever strokes S3 and S4. Therefore, the winch drum rotation speed between S1 and S4 is the same as that of the Lo/rating mode.
- the rotation speed of the winch drum 13 between the lever strokes S4 and S5 is, similar to the Hi/high-speed mode, increased up to N5 by the decrement of the capacity of the hydraulic motor responsive to the lever stroke and the increment of the flow rate determined by opening properties of the pilot-type operating valve 4.
- the winch drum rotation speed between the lever strokes S5 and S6 is the constant rotation speed N5 because the specific capacity of the hydraulic motor 6 is constant, and the flow rate is slightly increased by the increase in the lever stroke.
- the engine speed is increased in advance and then, the mode can be switched to the Hi/rating mode.
- numeral 6a denotes a main shaft of the hydraulic motor 6, 12 denotes a negative brake, 13a denotes a planetary reduction gear of the winch drum 13, and 16 denotes a rope wound around the winch drum 13.
- a hydraulic pipe not shown
- the rotation of the main shaft 6a is decelerated by the planetary reduction gear 13a to rotate the winch drum 13 in the direction of hoisting or in the direction of lowering, whereby the rope 16 performs hoisting or lowering of a suspended load.
- the auxiliary winding winch has a construction of axial symmetry with respect to the main winding winch of Fig. 4, so it is omitted.
- the present invention is useful as a method and a system for controlling the speed of a winch which connects dynamically a winch drum to a driving source at all times, thereby improving safety and operability without being put into a free fall state and, at the same time, offering a lowering speed equal to that of the free fall state.
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Abstract
The present invention relates to a method and a system
for controlling the speed of a winch, whereby safety and
operability are improved without being put into a free fall
state and, at the same time, a lowering speed equal to that
of the free fall state can be obtained. To this end, a
rotation speed of a winch drum (13) is substantially a
direct and exclusive speed with respect to the stroke of an
operating lever (5) until a predetermined stroke of the
operating lever (5), while the speed is a different speed
with respect to the same stroke of the operating lever (5)
in response to a speed mode selected from a plurality of
speed modes at strokes over the predetermined stroke.
Description
The present invention relates to a method and a system
for controlling the speed of a winch, and more particularly,
to a method and a system for controlling the speed of a
winch which drives a winch drum by oil pressure.
Hitherto, winch devices for use in a crane, etc. have
been designed to consist of, for example, a main winding
winch 50 and an auxiliary winding winch 60, as shown in Fig.
5. The main winding winch 50 driven by oil pressure is
comprised of a hydraulic motor 51, a reduction gear 52
driven by the hydraulic motor 51, an output axis 52a of the
reduction gear 52, and a clutch 53 provided on a driving
shaft 55 fixed to a main drum 56. In addition, a brake drum
54a is fixed to a flange of the main drum 56, and a band
brake 54 is wound around the brake drum 54a.
By the described arrangements, the rotation of the
hydraulic motor 51 is decelerated by the reduction gear 52
and transferred to the output shaft 52a, and when the clutch
53 is engaged, the rotation is transferred to the main drum
56 through the driving shaft 55. By controlling the
rotation of the hydraulic motor 51 with a known method, the
rotation of the main drum 56 can be controlled in response
to the rotation of the hydraulic motor 51. In addition,
when a light load, such as a hook, is lowered in a short
period of time, or when an impactive force of a hammer due
to a free fall is required, such as a piling operation in
construction work, the winch is used in a free fall state.
In these cases, disengagement of the clutch 53 puts the
suspended load of the main winding winch 50 into a free fall
state. In the case of controlling the falling speed, the
brake 54 is pressed against the brake drum 54a, and braking
force is adjusted by a degree of pressing. Therefore, when
the winch is used in the free fall state, the light load can
be lowered in a short period of time, and a large impactive
force by a heavy article such as a hammer can be obtained.
Incidentally, the arrangement and operation of the auxiliary
winding winch 60 are the same as those of the main winding
winch 50, and an explanation thereof is omitted.
However, according to the above prior art, when the
winch is used in the free fall state, the lowering speed of
the suspended load increases considerably regardless of an
operator's intention so that it becomes difficult to stop
the suspended load at a predetermined position. In
addition, there is a danger that a wrong operation of a
lever will suddenly put the winch into the free fall state,
and the suspended load will fall, so the operator is forced
to strain considerably.
The present invention has been made to solve the
problems of the prior art, and its object is to provide a
method of and a system for controlling the speed of a winch
which connects the driving device of a winch drum to the
winch drum at all times, thereby eliminating a free fall
state, and improving safety and operability for the
operator.
According to the present invention, there is provided a
method of controlling the speed of a winch which is operated
by controlling a rotation of a winch drum with an operating
lever, wherein the rotation speed of the winch drum is
substantially a direct and exclusive speed with respect to
the stroke of an operating lever until a predetermined
stroke of the operating lever, while the speed is a
different speed with respect to the same stroke of the
operating lever in response to a speed mode selected from a
plurality of speed modes at strokes over the predetermined
stroke. In addition, the selected speed mode may be
switched to another speed mode at the stroke in the middle
of the strokes over the predetermined stroke. The speed
mode may be switched, when switching from a low-speed speed
mode to a high-speed speed mode, under previously set
conditions. Further, the winch drum rotation speed until
the predetermined stroke may gradually increase in response
to an increase in the stroke of the operating lever, and may
be the same among the plurality of speed modes.
According to the described arrangements, the winch drum
rotation speed until the predetermined stroke is equal in
each speed mode, so that the operator's sense of operation
at the beginning of the operation is common, thus offering
good operability. In addition, at the strokes over the
predetermined stroke, the selection of, for example, a high-speed
speed mode increases the rotation speed and improves
working efficiency. Further, in the case of gradually
increasing the winch drum rotation speed, a reduction in the
rotation speed at the beginning of the operation improves
fine operability. As described above, different speed modes
can be selected as needed, thus offering high operability.
A first aspect of a system for controlling the speed of
a winch according to the present invention comprises a pilot
pipe for connecting a regulator for supplying control
pressure corresponding to pilot pressure to a control
cylinder of a variable hydraulic motor and a pilot valve for
supplying pilot pressure to a pilot-type operating valve,
and a mode switching open/close valve for communicating or
shutting off the pilot pipe. The regulator may be provided
with a setting means, and the setting means may stop an
operation of the regulator until a predetermined pilot
pressure, and may reduce a specific capacity of the variable
hydraulic motor in response to control pressure of the
regulator at pilot pressures over the predetermined pilot
pressure. In addition, the mode switching open/close valve
may be a solenoid-operated mode switching open/close valve
having a solenoid, and an operating lever knob of the pilot
valve may be provided with a switch so as to output an
electric signal from the switch to the solenoid. The
control pressure pipe for connecting the regulator and the
control cylinder may be provided with a restriction device.
Further, the system may comprise a capacity control means
for the variable hydraulic motor, a connecting means for
connecting the capacity control means and a piston rod of
the control cylinder, and a capacity setting means including
a capacity setting member and a stopper, wherein the
capacity setting member is fixed to any one of the capacity
control means, the piston rod, and the connecting means so
as to set a minimum capacity of the variable hydraulic
motor, and wherein the stopper restricts or releases the
movement of the capacity setting member.
According to the described arrangements, in a state
where the regulator and the pilot valve are in communication
with each other, the winch drum rotation speed is controlled
by the pilot-type operating valve and the variable hydraulic
motor of which the specific capacity is reduced by the
control cylinder. On the other hand, in a state where the
regulator and the pilot valve are shut off, the regulator is
not operated, so that the control pressure of the regulator
is not supplied to the control cylinder of the variable
hydraulic motor. Therefore, the winch drum rotation speed
is controlled by only the pilot-type operating valve which
is operated in response to pilot pressure.
In addition, when the above setting means (for example,
a spring attached to the regulator) is provided, control
pressure of the regulator is not supplied to the control
cylinder until a predetermined stroke of the operating
lever, so that the winch drum rotation speed is controlled
by the pilot-type operating valve. On the other hand, when
the operating lever exceeds the predetermined stroke, the
specific capacity of the variable hydraulic motor is reduced
by the control pressure of the regulator responsive to the
pilot pressure. Therefore, the winch drum rotation speed is
controlled by the reduced specific capacity and the pilot-type
operating valve. At this time, if the mode switching
open/close valve is shut off, the winch drum rotation speed
is controlled by only the pilot-type operating valve, so
that the speed reduces with respect to the same stroke of
the operating lever.
As described above, the winch drum rotation speed is
substantially directly and exclusively determined with
respect to the stroke of the operating lever until the
predetermined stroke regardless of communication and shut-off
of the mode switching open/close valve. On the other
hand, when exceeding the predetermined stroke, the winch
drum rotation speed becomes the speed corresponding to each
mode even at the same stroke of the operating lever.
In addition, when a switch is attached to the operating
lever knob, the speed mode can be switched by the switch
while controlling the winch drum rotation speed by the
operating lever. In addition, when the above restriction
device is provided, the specific capacity of the variable
hydraulic motor does not change abruptly, so that abrupt
changes in the winch drum rotation speed can be prevented,
thereby improving safety and durability of the device.
Further, by providing the above capacity setting means, the
variable hydraulic motor has a predetermined minimum
specific capacity when the stopper restricts the movement of
the capacity setting member. On the other hand, when the
movement restriction is released, the specific capacity of
the variable hydraulic motor can be reduced to 0, and the
winch can be operated into a free fall state.
Next, a second aspect of the system for controlling the
speed of a winch is characterized in that a selective valve
is attached, and that the selective valve selects higher
pressure of predetermined pressure of a pressure source and
driving pressure of the variable hydraulic motor so as to
supply the pressure as the main pressure of the regulator.
According to the described arrangements, the control
pressure supplied to the control cylinder of the variable
hydraulic motor employs a predetermined pressure of the
pressure source as the main pressure while the driving
pressure of the variable hydraulic motor is low. On the
other hand, when the driving pressure is increased, the
driving pressure is supplied as the main pressure of the
regulator to the control cylinder of the variable hydraulic
motor, so that the specific capacity of the variable
hydraulic motor can reliably be controlled.
Next, a third aspect of the system for controlling the
speed of a winch is characterized in that a directional
control valve is provided between a relief valve for
controlling a return oil pressure of the hydraulic motor at
the time of lowering the winch drum and a negative brake
provided on a connected portion of the hydraulic motor and
the winch drum, and that the directional control valve
passes therethrough or shuts off function releasing pilot
pressure for the relief valve, and opening pilot pressure
for the negative brake.
According to the described arrangements, when the
directional control valve is switched to a passing position,
the function releasing pilot pressure and the opening pilot
pressure are supplied, and the winch drum can be freely
rotated, so that maintenance and examination of the winch
can be easily effected.
The preferred embodiment of a method and a system for
controlling the speed of a winch according to the present
invention will now be described in detail with reference to
the attached drawings.
Referring to Fig. 1, numeral 1 denotes a winch pump for
driving a winch, 3 denotes a pressure compensating valve, 4
denotes a pilot-type operating valve, 5 denotes an operating
lever for operating the winch, 5a denotes a pilot valve for
supplying pilot pressure to the pilot-type operating valve
4, etc., and 5b denotes a high-speed mode switching button.
Numeral 6 denotes a hydraulic motor (a variable hydraulic
motor is used in this embodiment), 6b denotes a swash plate
(a capacity control means) provided in the hydraulic motor
6, 7a denotes a check valve, 7b denotes a relief valve, 8
denotes a control pump (pressure source) for supplying
control pressure of this speed control system, 9 denotes a
directional control valve for supplying the control pressure
of the motor, 9a is a directional control valve for
supplying control pressure of an auxiliary winding winch, 11
denotes a directional control valve for pilot main pressure
of the pilot pump 8 which is held in constant pressure by
the relief valve 10, 12 denotes a negative brake contained
in the hydraulic motor 6, and 13 denotes a winch drum driven
by the hydraulic motor 6.
In addition, numeral 18 denotes a high-speed mode
switching valve for switching pilot pressure of the pilot
valve 5a output through a shuttle valve 23, 19 denotes a
regulator for controlling capacity of the hydraulic motor 6
with a difference between the pilot pressure supplied
through the high-speed mode switching valve 18 and spring
force of a setting spring (setting means) 19a, 20 denotes a
control cylinder of the hydraulic motor 6, 20a denotes a
link (linking means) for linking between a piston rod of the
control cylinder 20 and the swash plate 6b, 21 denotes a
restrictor (restriction device) provided on a control
pressure pipe to the control cylinder 20, and 22 denotes a
relief valve provided on a driving main pipe of the
hydraulic motor 6.
Further, numeral 24 denotes a controller, and 24a
denotes an AND circuit which constitutes the controller 24.
The AND circuit 24 outputs an excitation signal to a
solenoid 18a of the high-speed mode switching valve 18 when
predetermined conditions, for example, in the case of this
embodiment, (i) an ON signal of the high-speed mode
switching button 5b, (ii) a pilot pressure signal Pd of a
lowering side of the pilot valve 5, and (iii) a
predetermined rope tension signal Ts are inputted at the
same time. The reasons for setting the above conditions
(ii) and (iii) for restricting a switching to the high-speed
mode are as follows. That is, the condition (ii) is set to
avoid a problem which arises in the case of speeding up a
hoisting operation, such as irregular winding of a rope due
to deterioration of rope winding properties over the drum,
or the generation of excessive shock due to a sudden stop at
the time of excessively hoisting a hook.
In addition, the condition (iii) is set to avoid
falling of a suspended load even if it exceeds the holding
capacity of the hydraulic motor. Moreover, since the above
(iii) hardly hoists and lowers a heavy load at a high speed
during a normal operation, it has an object to prevent an
excessive load on the entire device by restricting a high-speed
operable load to a light load below a predetermined
amount, and to enhance safety. Here, the rope tension is an
input signal corresponding to the suspended load, and a load
which directly acts on the winch device from the outside
becomes the input signal. The rope tension can be obtained,
for example, by dividing the suspended load obtained through
an overload protection device by the previously input number
of falls of the rope over the hook.
In addition, numeral 27 denotes a low-pressure relief
valve provided on a winch-lowering pipe, 28 denotes a tank,
30 denotes a drum-free switch, 31 denotes a drum-free
directional control valve, 32 denotes a restrictor provided
on a pipe which supplies a pilot main pressure of the pilot
pump 8 to the negative brake 12 through the brake valve 11,
33 denotes a solenoid open/close valve, 34 denotes a
capacity setting means including a capacity setting cylinder
34a and a capacity setting member 34b fixed to a piston rod
of the control cylinder 20, and 35a, 35b, and 35c denote
check valves.
Next, an operation of the above arrangement will be
described.
The speed mode of this embodiment includes the
following four modes: a Hi/rating mode and a Hi/high-speed
mode in a high-speed engine, and a Lo/rating mode and a
Lo/high-speed mode in a low-speed engine.
First, an operation of the main winding winch which is
common to each speed mode in this embodiment will be
described. Incidentally, the operation of the auxiliary
winding winch is the same as that of the main winding winch,
and an explanation thereof is omitted. Referring to Fig. 1,
when the operating lever 5 is operated, pilot pressure
responsive to an operating amount of the operating lever 5
is outputted from the pilot valve 5a to operate the pilot-type
operating valve 4. The flow rate responsive to an
operating amount of the pilot-type operating valve 4 is
supplied from the winch pump 1 and a boom pump (not shown)
to the hydraulic motor 6 and, at the same time, the
directional control valve 9 is switched to a position b by
load pressure taken out of the pilot-type operating valve 4,
whereby control pressure of the pilot pump 8 is supplied to
the brake valve 11 through the position b of the directional
control valve 9 and the restrictor 32, so that braking of
the negative brake 12 is released. This release causes the
winch drum 13 to be rotated at rotation speed responsive to
the operating amount of the operating lever 5.
In the case of abruptly operating the above operating
lever 5 is abruptly operated to the lowering side, the winch
drum 13 is going to rotate abruptly to the lowering side.
However, working fluid of the lowering side pipe is relieved
by the relief valve 27 which is set to a predetermined
pressure, so that an abrupt increase in the rotation speed
to the lowering side is prevented, whereby an irregular
winding of the wire can be prevented.
Incidentally, in the case of freely rotating the winch
drum 13, by turning the drum-free switch 30 on, the drum-free
directional control valve 31 is changed into the
position b, and the brake valve 11 is changed into the
position a, whereby the negative brake 12 is opened by
control pressure of the control pump 8, and the control
pressure of the control pump 8 is supplied to the relief
valve 7b, so that the winch drum 13 can rotate freely also
to the lowering side.
In addition, as another free rotational operation, an
electric signal of a non-illustrated switch is first
outputted to a solenoid of the brake valve 11, and the brake
valve 11 is changed into the position a so as to open the
negative brake 12. At the same time, the electric signal is
also outputted to a solenoid of the solenoid open/close
valve 33, and the solenoid open/close valve 33 is changed
into the position b, whereby the control pressure of the
control pump 8 is supplied to a rod chamber of the capacity
setting cylinder 34a and the control cylinder 20. This
causes a rod (stopper) of the capacity setting cylinder 34a
to constrict, thereby releasing movement restrictions of the
capacity setting member 34b. The released capacity setting
member 34b moves the swash plate 6b through the piston rod
of the control cylinder 20 and the link 20a to set the
capacity of the hydraulic motor 6 to 0 cc/rev. Therefore,
when the lowering speed faster than that of the Hi/high-speed
mode is required, setting the capacity of the
hydraulic motor 6 to 0cc/rev as described above enables a
free fall operation even if the clutch is omitted.
Fig. 2 shows four kinds of speed modes in this
embodiment. Here, in order to simplify the description, the
speed mode is represented by two states: a Hi state in which
the engine speed is equivalent to a high-idle rotating
state, and a Lo state in which the engine speed is
equivalent to a low-idle rotation state. As the actual
operating conditions, the speed mode may naturally be set to
a state equivalent to a middle of them. In addition, even
if the engine speed is kept constant, it is possible to
change a maximum flow rate to the hydraulic motor so as to
set the speed mode to the above Hi, Lo and the middle state
by a method of changing the number of hydraulic pumps which
supplies working fluid to the hydraulic motor in response to
the specific capacity of the hydraulic pump or the speed
mode. Further, although the specific capacity of the
hydraulic motor is changed from V to 0.5 V in the high-speed
mode, a minimum specific capacity is not limited to 0.5 V.
Therefore, it is a matter of course that the specific
capacity of the hydraulic motor can suitably be selected,
and that the above high-speed mode is pluralized by setting
the minimum specific capacity in the plural.
Fig. 3 is an illustration of the system for controlling
the speed of a winch according to the above-described
arrangements. Each mode at the time of lowering by the main
winding winch shown in the right of Fig. 3 will be described
with reference to the operating conditions of Fig. 2, and
Fig. 1.
A section between lever strokes N and S1 is a dead zone
due to leakage oil of hydraulic equipment such as the
hydraulic pump 1 and the hydraulic motor 6, and the winch
drum 13 does not rotate. Incidentally, the winch drum 13 in
the section between the lever strokes N and S1 does not
rotate in any mode of the Hi/high-speed mode, Lo/rating
mode, and Lo/high-speed mode to be described later. Next,
the drum rotation speed between lever strokes S1 and S6 is
increased up to N6 by a flow rate determined by opening
properties of the pilot-type operating valve 4.
Incidentally, the drum rotation speed is illustrated taking
the rated rotation speed N6 as 100 %.
In a state where the pilot pressure signal Pd output
from a pressure switch (provided on the pilot pipe of the
lowering side of the pilot-type operating valve 4) and the
rope load signal TS which is a predetermined safe load are
inputted in the AND circuit 24a of the controller 24, when
the high-speed mode switching button 5b of the operating
lever 5 is pushed, the high-speed mode switching valve 18 is
changed into the position b by signals from the AND circuit
24a.
Therefore, pilot pressure of the pilot valve 5a is
supplied to the capacity controlling regulator 19 in
response to the lever stroke of the operating lever 5.
However, pressing force due to the pilot pressure is set
smaller than spring force of the setting spring 19a between
the lever strokes S1 and S4, so that the capacity
controlling regulator 19 remains in the position b.
The drum rotation speed between the lever strokes S1
and S4 is increased up to N4 by opening properties of the
pilot-type operating valve 4. The drum rotation speed
between the lever strokes S1 and S4 is the same as that in
the Hi/rating mode. When the lever stroke reaches S4, the
pressing force of the capacity controlling regulator 19
becomes larger than the spring force of the setting spring
19a, so that the capacity controlling regulator 19 is
started to operate in the a direction.
The specific capacity of the hydraulic motor 6 is
decreased from V to 0.5 V by the pilot pressure responsive
to the lever stroke between the lever strokes S4 and S5, and
the rotation speed of the winch drum 13 is increased up to
N7 in response to an increase in flow rate by the pilot-type
operating valve 4. That is, the winch drum rotation speed
between S4 and S5 becomes twice the speed of the Hi/rating
mode. The specific capacity of the hydraulic motor 6 is
constant between the lever strokes S5 and S6, and the flow
rate determined by opening properties of the pilot-type
operating valve 4 due to the lever stroke slightly
increases, so that the winch drum rotation speed remains
constant at N7.
Incidentally, between the lever strokes S4 and S6, by
releasing press of the high-speed mode switching button 5,
the rotation speed is switched from the position P to the
position Q. Conversely, by pressing the high-speed mode
switching button 5b, the switching from the position Q to
the position P can be done.
In addition, as regards the main pressure of the
capacity controlling regulator 19, the higher oil pressure
of the higher driving pressure of the hydraulic motor 6
selected by the check valves 35a and 35b, and discharge
pressure of the control pump 8 which is held at a
predetermined pressure by the relief valve 10 is selected by
the check valve 35c (selective valve). The main pressure is
reduced in response to the operating amount of the regulator
19 responsive to the lever stroke, and is supplied to the
control cylinder 20 of the hydraulic motor 6. Therefore,
the control pressure supplied to the control cylinder 20 is,
while the driving pressure of the hydraulic motor 6 is low,
secured by the discharge pressure of the control pump 8 held
at a predetermined pressure. On the other hand, when the
driving pressure of the hydraulic motor 6 increases, the
driving pressure is supplied to the control cylinder 20 as
the main pressure of the capacity controlling regulator 19,
so that the capacity of the hydraulic motor 6 can reliably
be controlled.
The winch rotation speed between the lever strokes S1
and S3 is increased up to N3 by opening properties of the
pilot-type operating valve 4. Next, the winch drum rotation
speed between the lever strokes S3 and S6 remains constant
at N3 because the flow rate flowing into the pilot-type
operating valve 4 is a predetermined maximum flow rate
(constant) corresponding to the Lo rating mode.
The winch drum rotation speed is increased up to N3 by
the pilot-type operating valve 4 between the lever strokes
S1 and S3, and is constant at N3 between the lever strokes
S3 and S4. Therefore, the winch drum rotation speed between
S1 and S4 is the same as that of the Lo/rating mode. The
rotation speed of the winch drum 13 between the lever
strokes S4 and S5 is, similar to the Hi/high-speed mode,
increased up to N5 by the decrement of the capacity of the
hydraulic motor responsive to the lever stroke and the
increment of the flow rate determined by opening properties
of the pilot-type operating valve 4. The winch drum
rotation speed between the lever strokes S5 and S6 is the
constant rotation speed N5 because the specific capacity of
the hydraulic motor 6 is constant, and the flow rate is
slightly increased by the increase in the lever stroke.
In addition, as in the case of the Hi/high-speed mode,
between the lever strokes S4 and S6, by releasing the high-speed
mode switching button 5, the rotation speed is
switched from the position T to the position S, and by
pushing the high-speed mode switching button 5b, the
switching from the position S to the position T can be done.
Incidentally, when a change from the Lo/high-speed mode
to the Hi/rating mode is required, the engine speed is
increased in advance and then, the mode can be switched to
the Hi/rating mode.
Although each mode at the time of lowering by the main
winding is described above, the relationship between lever
stroke and winch drum rotation speed on the hoisting side
(the left of Fig. 3) of the main winding winch is such that
the absolute values are equal and only the direction of
rotation is reversed with respect to the Hi/rating mode and
the Lo/rating mode on the lowering side, so an explanation
thereof is omitted. In addition, the operation of the
auxiliary winding winch is the same as that of the main
winding winch, so an explanation thereof is omitted.
Referring to Fig. 4, numeral 6a denotes a main shaft of
the hydraulic motor 6, 12 denotes a negative brake, 13a
denotes a planetary reduction gear of the winch drum 13, and
16 denotes a rope wound around the winch drum 13. An
operation of the described arrangements will be described.
When working fluid is supplied from a hydraulic pipe (not
shown) to the hydraulic motor 6, the main shaft 6a rotates
at a speed determined by the flow rate of the working fluid
and the specific capacity of the hydraulic motor 6. The
rotation of the main shaft 6a is decelerated by the
planetary reduction gear 13a to rotate the winch drum 13 in
the direction of hoisting or in the direction of lowering,
whereby the rope 16 performs hoisting or lowering of a
suspended load. Incidentally, the auxiliary winding winch
has a construction of axial symmetry with respect to the
main winding winch of Fig. 4, so it is omitted.
The present invention is useful as a method and a
system for controlling the speed of a winch which connects
dynamically a winch drum to a driving source at all times,
thereby improving safety and operability without being put
into a free fall state and, at the same time, offering a
lowering speed equal to that of the free fall state.
Claims (11)
- A method of controlling the speed of a winch which is operated by controlling a rotation of a winch drum with an operating lever, wherein the rotation speed of said winch drum is substantially a direct and exclusive speed with respect to the stroke of an operating lever until a predetermined stroke of the operating lever, while the speed is a different speed with respect to the same stroke of the operating lever in response to a speed mode selected from a plurality of speed modes at strokes over the predetermined stroke.
- A method of controlling the speed of a winch according to claim 1, wherein said selected speed mode is switched to another speed mode at the stroke in the middle of said strokes over the predetermined stroke.
- A method of controlling the speed of a winch according to claim 2, wherein said speed mode can be switched, when switching from a low-speed speed mode to a high-speed speed mode, under previously set conditions.
- A method of controlling the speed of a winch according to claim 1, wherein the winch drum rotation speed until said predetermined stroke gradually increases in response to an increase in the stroke of the operating lever, and is the same among said plurality of speed modes.
- A system for controlling the speed of a winch including a hydraulic pump, a variable hydraulic motor for driving a winch drum, a pilot-type operating valve provided between said hydraulic pump and said variable hydraulic motor for operating the rotation speed of said winch drum, a pilot valve for supplying pilot pressure to said pilot-type operating valve, and a regulator for supplying control pressure corresponding to said pilot pressure to a control cylinder of said variable hydraulic motor, said system comprising a pilot pipe for connecting said regulator and said pilot valve, and a mode switching open/close valve for communicating or shutting off said pilot pipe.
- A system for controlling the speed of a winch according to claim 5, wherein said regulator is provided with a setting means, and said setting means stops an operation of said regulator until a predetermined pilot pressure, and reduces a specific capacity of said variable hydraulic motor in response to control pressure of said regulator at pilot pressures over the predetermined pilot pressure.
- A system for controlling the speed of a winch according to claim 5, wherein said mode switching open/close valve is a solenoid-operated mode switching open/close valve having a solenoid, and wherein an operating lever knob of said pilot valve is provided with a switch so that an electric signal is outputted from said switch to said solenoid.
- A system for controlling the speed of a winch according to claim 5, wherein said control pressure pipe for connecting said regulator and said control cylinder is provided with a restriction device.
- A system for controlling the speed of a winch according to claim 5, further comprising a capacity control means for said variable hydraulic motor, a connecting means for connecting said capacity control means and a piston rod of said control cylinder, and a capacity setting means including a capacity setting member and a stopper, wherein said capacity setting member is fixed to any one of said capacity control means, said piston rod, and said connecting means so as to set a minimum capacity of said variable hydraulic motor, and wherein said stopper restricts or releases the movement of said capacity setting member.
- A system for controlling the speed of a winch including a hydraulic pump, a variable hydraulic motor for driving a winch drum, a pilot-type operating valve provided between said hydraulic pump and said variable hydraulic motor for operating the rotation speed of said winch drum, a pilot valve for supplying pilot pressure to said pilot-type operating valve, and a regulator for supplying control pressure corresponding to said pilot pressure to a control cylinder of said variable hydraulic motor, wherein a selective valve is attached to said system, and wherein said selective valve selects higher pressure of predetermined pressure of a pressure source and driving pressure of said variable hydraulic motor so as to supply the pressure as the main pressure of said regulator.
- A system for controlling the speed of a winch including a hydraulic pump, a hydraulic motor for driving a winch drum, an operating valve provided between said hydraulic pump and said hydraulic motor for operating the rotation speed of said winch drum, a hydraulic driving pipe for connecting these components, a relief valve provided on the winch drum hoisting side of said hydraulic driving pipe for controlling a return oil pressure of said hydraulic motor at the time of lowering the winch drum, and a negative brake provided on a connected portion of said hydraulic motor and said winch drum, wherein a directional control valve is provided between said relief valve and said negative brake, and wherein said directional control valve passes therethrough or shuts off function releasing pilot pressure for said relief valve, and opening pilot pressure for said negative brake.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP1995/000394 WO1996028377A1 (en) | 1995-03-10 | 1995-03-10 | Method and system for controlling the speed of a winch |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0819646A1 true EP0819646A1 (en) | 1998-01-21 |
EP0819646A4 EP0819646A4 (en) | 2000-01-05 |
Family
ID=14125723
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95910783A Withdrawn EP0819646A4 (en) | 1995-03-10 | 1995-03-10 | Method and system for controlling the speed of a winch |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0819646A4 (en) |
KR (1) | KR19980702858A (en) |
WO (1) | WO1996028377A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102745617A (en) * | 2012-07-02 | 2012-10-24 | 中联重科股份有限公司 | Control method, controller and control system for free falling of locking device and crane |
KR102662414B1 (en) * | 2023-10-12 | 2024-04-30 | 주식회사 제이피케이이노 | Winch brake structure |
KR102662416B1 (en) * | 2023-10-12 | 2024-04-30 | 주식회사 제이피케이이노 | Winch brake system with increased performance |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20160150556A (en) | 2015-06-22 | 2016-12-30 | 디와이 주식회사 | Crane apparatus |
CN114857101B (en) * | 2022-05-20 | 2024-04-05 | 宁波新宏液压有限公司 | Intelligent protection system of speed-regulating hydraulic winch |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3870255A (en) * | 1970-07-07 | 1975-03-11 | Hughes Tool Co | Hoist drive system |
US5355675A (en) * | 1993-08-31 | 1994-10-18 | Western Atlas International, Inc. | Stabilized speed-control system for a hydrostatic transmission |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5554712Y2 (en) * | 1976-09-13 | 1980-12-17 | ||
JPS54138265A (en) * | 1978-04-19 | 1979-10-26 | Hitachi Ltd | Method of and apparatus for controlling operation of constant-output hydraulic hoist |
JPS5958203A (en) * | 1982-09-28 | 1984-04-03 | Yanase:Kk | Automatic operation control method for variable stroke volume piston type hydraulic motor |
JPS61127968A (en) * | 1984-11-22 | 1986-06-16 | Hitachi Constr Mach Co Ltd | Speed controller for hydraulic closed circuit drive unit |
JPS62105895A (en) * | 1985-10-31 | 1987-05-16 | 住友重機械工業株式会社 | Hydraulic circuit |
JPS6428200A (en) * | 1987-07-22 | 1989-01-30 | Kobe Steel Ltd | Controller for hydraulic winch |
JPS6487495A (en) * | 1987-09-28 | 1989-03-31 | Hitachi Construction Machinery | Hydraulic winch circuit with variable displacement type hydraulic motor |
-
1995
- 1995-03-10 EP EP95910783A patent/EP0819646A4/en not_active Withdrawn
- 1995-03-10 KR KR1019970706265A patent/KR19980702858A/en not_active Application Discontinuation
- 1995-03-10 WO PCT/JP1995/000394 patent/WO1996028377A1/en not_active Application Discontinuation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3870255A (en) * | 1970-07-07 | 1975-03-11 | Hughes Tool Co | Hoist drive system |
US5355675A (en) * | 1993-08-31 | 1994-10-18 | Western Atlas International, Inc. | Stabilized speed-control system for a hydrostatic transmission |
Non-Patent Citations (1)
Title |
---|
See also references of WO9628377A1 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102745617A (en) * | 2012-07-02 | 2012-10-24 | 中联重科股份有限公司 | Control method, controller and control system for free falling of locking device and crane |
KR102662414B1 (en) * | 2023-10-12 | 2024-04-30 | 주식회사 제이피케이이노 | Winch brake structure |
KR102662416B1 (en) * | 2023-10-12 | 2024-04-30 | 주식회사 제이피케이이노 | Winch brake system with increased performance |
Also Published As
Publication number | Publication date |
---|---|
KR19980702858A (en) | 1998-08-05 |
EP0819646A4 (en) | 2000-01-05 |
WO1996028377A1 (en) | 1996-09-19 |
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