Fluid Resistance Brake Patents (Class 254/377)
  • Patent number: 11840422
    Abstract: A braking system for a hose or cable reel including a housing configured to fit inside a drum of the reel and to rotate with the drum during use, and a gerotor including inner and outer gears disposed inside the housing, wherein the inner gear is attachable to a shaft of the reel and the outer gear is configured to rotate relative to the inner gear with the housing during use thereby causing hydraulic fluid to be pumped through the gerotor and impede rotation of the drum.
    Type: Grant
    Filed: August 20, 2018
    Date of Patent: December 12, 2023
    Assignee: MACNAUGHT PTY LTD
    Inventors: Marco Uccellani, Prabhjot Singh
  • Patent number: 9150391
    Abstract: A hoist system includes a drum, a motor, and a transmission. The drum includes a hollow shell, a first end, a second end, and an internal web, and defines a longitudinal axis extending between the first end and the second end. The internal web extends across an interior portion of the shell in a direction perpendicular to the longitudinal axis, thereby defining a first portion and a second portion of the shell. The motor is coupled to the first end and includes an output shaft. The transmission is driven by the motor and includes a planetary gear train positioned within the interior portion of the shell. The planetary gear train includes an input gear coupled to the motor output shaft and an output gear coupled to the internal web to rotate the drum about the longitudinal axis. The planetary gear train is positioned in a first portion of the shell.
    Type: Grant
    Filed: March 13, 2013
    Date of Patent: October 6, 2015
    Assignee: Harnischfeger Technologies, Inc.
    Inventors: Andrew M. Wurster, Peter Sandoval, Jr., Edwin C. Hahlbeck
  • Patent number: 8997888
    Abstract: A multi purpose hoisting device for use on a floating vessel having a deck, including: a load bearing structure to be mounted on the vessel; a main hoisting mechanism for raising/lowering an object above the deck and including: at least one main hoisting winch; an upper cable pulley block supported by the load bearing structure; a travelling cable pulley block; a main hoisting cable associated with the at least one main hoisting winch and passed over pulleys of the upper cable pulley block and of the travelling pulley block in a multiple fall configuration, such that the travelling cable pulley block is moveable relative to the load bearing structure by using the at least one main hoisting winch; a main hoist heave compensation mechanism associated with the main hoisting cable for damping the effect of sea-state induced motion of the vessel onto an object supported by the main hoisting cable.
    Type: Grant
    Filed: September 16, 2010
    Date of Patent: April 7, 2015
    Assignee: ITREC B.V.
    Inventors: Joop Roodenburg, Diederick Bernardus Wijning
  • Patent number: 8246010
    Abstract: A fluid shear actuated brake mechanism includes an outer hub secured to a hoist frame, a main brake disc stack engaged between the outer hub and a hoist drum shaft, an actuator hub helically engaged with the outer hub, and an actuator disc stack engaged between the actuator hub and the shaft. The main disc stack and the actuator disc stack are immersed in a fluid. Rotation of the shaft in a load lowering direction generates fluid shear in the actuator disc stack which rotates the actuator hub in a lowering direction and advances it toward the main disc stack, compressing it and the actuator disc stack. Rotation of the shaft in an opposite load lift direction retract the actuator hub from the main disc stack.
    Type: Grant
    Filed: August 13, 2009
    Date of Patent: August 21, 2012
    Inventor: Daniel L. Hess
  • Patent number: 7201366
    Abstract: An electronic winch monitoring system for a winch having a fixed-ratio gearbox with input and output shafts, a winch drum connected to the output shaft, and an auxiliary brake connected to the output shaft activated by reducing the pressure in a brake release hydraulic circuit. The system comprises an input shaft speed sensor, an output shaft speed sensor, and an electronic control unit having a monitoring section and a brake control section. The monitoring section receives the speed signals, processes them to produce a calculated ratio of actual input to output shaft speeds, and produces a fault indication signal when the value of the difference between the calculated speed ratio and the fixed ratio exceeds a predetermined value. The brake control section, upon receiving the fault signal, reduces the hydraulic pressure in the brake circuit using a nonlinear pressure-time profile to engage the auxiliary brake and stop the winch drum.
    Type: Grant
    Filed: May 1, 2006
    Date of Patent: April 10, 2007
    Assignee: Paccar Inc.
    Inventors: Mark E. Sanders, David E. Johnson
  • Patent number: 7166061
    Abstract: According to a control device for a hydraulic winch, a regulator controls a motor capacity of a hydraulic motor having variable capacity functioning as a driving source of the hydraulic winch in response to a load pressure, a negative brake stops and retains the hydraulic motor at an automatic shutoff for prevention of overloading, and a controller sends signals to the regulator via a regulator-controlling valve at the automatic shutoff to set the motor capacity at a large value. Thus, the delay to recover the motor capacity at the time of returning from the automatic shutoff that is activated during winding-up of a load does not occur, and a control response is increased.
    Type: Grant
    Filed: December 20, 2004
    Date of Patent: January 23, 2007
    Assignee: Kobelco Cranes Co., Ltd.
    Inventors: Koichi Shimomura, Masaaki Ehara
  • Patent number: 7063306
    Abstract: An electronic winch monitoring system for a winch having a fixed-ratio gearbox with input and output shafts, a winch drum connected to the output shaft, and an auxiliary brake connected to the output shaft activated by reducing the pressure in a brake release hydraulic circuit. The system comprises an input shaft speed sensor, an output shaft speed sensor, and an electronic control unit having a monitoring section and a brake control section. The monitoring section receives the speed signals, processes them to produce a calculated ratio of actual input to output shaft speeds, and produces a fault indication signal when the value of the difference between the calculated speed ratio and the fixed ratio exceeds a predetermined value. The brake control section, upon receiving the fault signal, reduces the hydraulic pressure in the brake circuit using a nonlinear pressure-time profile to engage the auxiliary brake and stop the winch drum.
    Type: Grant
    Filed: July 9, 2004
    Date of Patent: June 20, 2006
    Assignee: PACCAR Inc
    Inventors: Mark E. Sanders, David E. Johnson
  • Patent number: 6672428
    Abstract: A small and easily portable apparatus for safely descending from a high elevation, comprising a drum rotatably mounted on a mounting frame; a body securing device for securing the mounting frame to the body of a user; and a line wound around the drum, having an end for attachment to a fixed object at the high elevation; such that the user may attach the line to a fixed object and safely descend from the high elevation.
    Type: Grant
    Filed: February 28, 2002
    Date of Patent: January 6, 2004
    Inventor: Boris Gelman
  • Patent number: 6371447
    Abstract: According to the present invention, when a winch drum is in the wind-down rotation, operating a control valve is operated to the wind-down side in a state in which capacity of a hydraulic motor is set to small capacity by a free fall valve to thereby rotate the hydraulic motor to the wind-down side at high speeds, and at the same time, motor holding pressure is controlled according to an operating amount of the free fall valve by a holding pressure control valve to thereby regulate rotational speed of the hydraulic motor and stop the latter.
    Type: Grant
    Filed: December 22, 1999
    Date of Patent: April 16, 2002
    Assignee: Kobelco Construction Machinery Co., Ltd.
    Inventors: Etsujiro Imanishi, Satoshi Yonezawa, Takahiro Kobayashi, Yoshio Nishimoto, Taisuke Tsunoo
  • Patent number: 6234417
    Abstract: A take-up reel for winding and storing an elongate hose or electrical cable comprises a reel supported by a stationary support shaft and urged in a first direction by a torsional spring. A viscous clutch assembly comprising multiple disks housed in a chamber filled with a viscous fluid is coupled to the reel to provide a retarding force that is proportional to velocity. The velocity proportional retarding force causes the rewind velocity of the reel to stabilize at a constant velocity. A one-way clutch is provided to decouple the viscous clutch from the reel when the hose or cable is being payed-out thereby permitting the hose or cable to be payed-out without resistance from the viscous clutch. By providing a unidirectional viscous clutch that acts to retard only the take-up velocity of the hose reel, it is possible to provide an apparatus that permits the hose to be payed-out at any speed while providing the substantial safety benefits of a viscous speed governor during take-up.
    Type: Grant
    Filed: June 1, 1999
    Date of Patent: May 22, 2001
    Assignee: Coxwells, Inc.
    Inventors: Gerald D. Sauder, Andre J. Baca
  • Patent number: 6092789
    Abstract: A boom hoist system for supporting and adjusting the position of a lifting crane gantry is provided including a drum, a drive system, and first and second braking systems for selectively stopping rotation of the drum. The boom hoist system operates independently from crane mechanical works and the first and second braking systems may include sensors for automatically engaging when specified conditions occur in order to prevent a hoisted gantry from falling uncontrollably in the event of a hoist system malfunction or failure.
    Type: Grant
    Filed: March 19, 1998
    Date of Patent: July 25, 2000
    Assignees: Hugo Nev Corporation, Joint Venture Operations, Inc.
    Inventors: Patrick Christopher, Daniel R. Juneau, Herman J. Schellstede
  • Patent number: 6012707
    Abstract: An arrangement for controlling a winch cable connected to rock drilling equipment, the arrangement including the winch; a pressure fluid motor arranged to operate the winch; a pressure fluid pump for operating the pressure fluid motor; a pressure-controlled pressure relief valve installed between a pair of pressure fluid channels connected to the pressure fluid motor for setting a counterpressure of the pressure fluid motor when pulling the cable off a drum; and control means for controlling counterpressure of the pump; wherein the pump is a pressure-controlled volume flow pump and the control means comprise an adjusting device with which a control pressure prevailing in a control channel of the pressure relief valve can be adjusted for setting a limit pressure of the pressure relief valve and thus the counterpressure of the pressure fluid motor.
    Type: Grant
    Filed: November 19, 1997
    Date of Patent: January 11, 2000
    Assignee: Tamrock Oy
    Inventor: Pentti Enlund
  • Patent number: 5984277
    Abstract: The present invention relates to a method of operating a winch, in which a rope which is wound onto a driven reel is supplied to at least one capstan head and wound around said capstan head, with a capstan drive rotating the capstan head and producing a rope advance due to the rope friction existing between rope and capstan head. Moreover, the present invention relates to a corresponding device. As an improvement of the method and the device, the invention suggests a reel drive which is adjusted separately next to the capstan drive.
    Type: Grant
    Filed: December 10, 1997
    Date of Patent: November 16, 1999
    Assignee: Kaessbohrer Gelaendefahrzeug GmbH
    Inventors: Helmut Kanzler, Alfons Rock, Gerhard Ummenhofer
  • Patent number: 5860635
    Abstract: A new and useful winch comprising a cable drum; a motor operatively connected to drive a cable drum; a fall arrestor operatively connected to a cable drum and having no power input requirement and a gear reduction group through which a motor and fall arrestor are operatively connected to a cable drum.
    Type: Grant
    Filed: December 21, 1995
    Date of Patent: January 19, 1999
    Assignee: Seascape Systems Limited
    Inventors: Jeffrey Morfitt, Barrie Freeke
  • Patent number: 5794880
    Abstract: A driven barrel of a winch device includes a closed cylindrical space (16) which is concentric with the barrel and accommodates a piston (17) which can move on an axis (12) from one end of the cylindrical space to the other and is in non-rotatable connection (19, 20) with the inside of the barrel. The axis (12) has screw threads (15) and the piston (17) has a center bore with screw threads meshing with the screw threads of the axis. The cylindrical space encloses a fluid and the piston (17) is given a leak from one side of the piston to the other. In order to stop the loaded rope unwinding from the barrel if the rotation speed of the barrel should increase over a certain value the leak is in the form of a canal (21) which accommodates a valve means including a valve housing and a valve body (22). The valve means stops the fluid flow over the valve body in one direction at a certain pressure drop over the valve body.
    Type: Grant
    Filed: July 2, 1996
    Date of Patent: August 18, 1998
    Inventor: Gunnar Liljedahl
  • Patent number: 5794920
    Abstract: A hydraulic motor is configured to drive a cable spool. A first fluid diverting valve is hydraulically connected between a discharge of a vehicle steering pump and the hydraulic motor. The first fluid diverting valve is configured to divert full fluid flow to a vehicle power steering box, and to divert full fluid flow to the hydraulic motor. A second fluid diverting valve is hydraulically connected between the first fluid diverting valve and an inlet of the vehicle steering pump. The second fluid diverting valve is configured to divert full fluid flow from the first fluid diverting valve to the hydraulic motor and to divert full fluid flow from the first fluid diverting valve to the inlet of the vehicle steering pump, bypassing the hydraulic motor and permitting fluid flow between the inlet of the hydraulic motor and the outlet of the hydraulic motor through the second fluid diverting valve so that manual operation of the winch is permitted.
    Type: Grant
    Filed: November 11, 1997
    Date of Patent: August 18, 1998
    Inventor: Gale A. Kronberger
  • Patent number: 5735506
    Abstract: A winch operates with a hydraulic motor which is supplied by a servo-valve. The servo-valve is connected as a 3-way system so that the supply hose used as a discharge when the load is being winched up is connected directly to the fluid return and so that during the descent, this motor is no longer supplied with high pressure and the fluid is circulated in a closed circuit without pressure. Fluid is refreshed with a flow rate low enough so that it does not excessively increase the supply of energy, but high enough that it limits the overheating of the fluid.
    Type: Grant
    Filed: June 28, 1996
    Date of Patent: April 7, 1998
    Assignee: Thomson-CSF
    Inventors: Fran.cedilla.ois Warnan, Daniel Canto
  • Patent number: 5709285
    Abstract: A brake for a hoisting apparatus including a hoisting line, a drum for the hoisting line, a hoisting motor and a brake system for braking of the hoisting cable, the brake system consisting of a hydraulic brake and a mechanical brake. The mechanical and the hydraulic brakes are connected to a common transmission which is driven by the drum when this rotates freely, and the mechanical and the hydraulic brakes are controlled by a common controller for controlling the distribution of braking power between the two brakes. The control system distributes the braking power automatically between the brake systems. The transmission can also be connected to an autodriller for controlling the weight on the bit.
    Type: Grant
    Filed: October 3, 1995
    Date of Patent: January 20, 1998
    Assignee: Maritime Hydraulics AS
    Inventors: Marek Sokalski, Erik Zachariassen
  • Patent number: 5046402
    Abstract: The device serves to convert rotary motion to hydraulic pressure and vice versa. A piston assembly is entirely located within a cylinder, including a piston head and a piston stem fixed to the piston head. The piston assembly divides the cylinder into two distinct variable volume chambers to be filled with a fluid. The piston assembly is prevented from rotating relative to the cylinder. A rotary shaft extends through one closed end of the cylinder and has an inner portion in telescopic and threaded engagement with the piston stem. Two fluid ports communicate with the respective chambers for allowing a fluid to alternatively exit from and enter into the chambers. Rotation of the shaft causes longitudinal displacement of the piston assembly relative to the cylinder or vice versa. The device can have different applications: for instance, if a throttle valve is connected across the two ports, controlled braking of the shaft rotated by an external torque, is obtained.
    Type: Grant
    Filed: April 23, 1990
    Date of Patent: September 10, 1991
    Inventor: Jean-Hugues Lagace
  • Patent number: 4875530
    Abstract: Maximum rate of drill bit penetration in high speed coring is achieved by precise control of bit weight and bit speed. The automatic drilling system of this invention makes it possible to quickly reach and maintain this optimum combination or "sweet-point" each time the core bit is started. The required speed and weight is input into the system by the operator. A controller electronically senses the bit weight and provides instantaneous feedback to a hydraulically driven drawworks which is capable of maintaining a precise weight on the bit throughout varying penetration modes. The drilling system uses a combination of equipment that includes a hydraulic system for the control of the drawworks; a solid-state strain gauge load cell apparatus built into the swivel assembly for continuously weighing the drill string; an electronic load control circuitry for determining the bit weight, drill string weight, and for maintaining the bit weight control; and, a top drive system for high speed rotation of the string.
    Type: Grant
    Filed: March 24, 1989
    Date of Patent: October 24, 1989
    Assignee: Parker Technology, Inc.
    Inventors: Tommy S. Frink, Lowell M. Reed, Dwayne V. Cochran, Will L. McNair
  • Patent number: 4756366
    Abstract: A portable workover rig for lowering and raising objects such as pipe into and out of a borehole and includes a mast which can be raised from the horizontal position to a vertical position. a first hydraulic motor drives a sandline drum and a second hydraulic motor drives a mainline drum. A normally closed pilot operated check valve provided in the power hydraulic fluid conduit can be opened to permit freewheeling of the main drum allowing heavy objects to free fall in the wellbore. The mainline drum's motor is controlled by a control valve having a counterbalance feature which when a heavy load is being lowered into the well bore prevents the drum from rotating faster than it would be driven by the power hydraulic fluid. A similar but separate control system is used for the sandline drum.
    Type: Grant
    Filed: March 10, 1987
    Date of Patent: July 12, 1988
    Assignee: Crane Carrier, Co.
    Inventors: Peter F. Maroney, Frank C. Blalock
  • Patent number: 4722422
    Abstract: An emergency escape apparatus allows safe escape from a tall building on fire. It includes a case carried by a user on his back. A wire wound around a reel mounted in the case has one end secured to the case. With the other end of the wire secured to the building, the user jumps down. The wire is drawn out of the case, and a brake device in the case applies a braking force to the wire, allowing the user land softly.
    Type: Grant
    Filed: March 3, 1986
    Date of Patent: February 2, 1988
    Inventor: Kunizo Hiraoka
  • Patent number: 4625933
    Abstract: The invention relates to a process and device for regulating at any instant the speed of a mobile member, such as a pulley, moving in a stroke of determined uniform direction, by employing a fluid passing under pressure through an orifice of restricted section. According to the invention, said pressurized fluid is made to pass several times alternately in one direction and in the other through said orifice, during said stroke of determined uniform direction. The invention is more particularly applicable to the deployment of appendices mounted on board space vessels.
    Type: Grant
    Filed: September 17, 1984
    Date of Patent: December 2, 1986
    Assignee: Societe Nationale Industrielle Aerospatiale
    Inventors: Gerard Luciano, Pierre Poveda, Pierre Croiset
  • Patent number: 4566675
    Abstract: A control device for an air hoist drives an air motor rotated by an air supply. The air hoist lifts or lowers a load by rotating a chain wheel. When the chain wheel rotates to lower the load, a small amount of air is supplied to the air motor in order to drive it in the normal lifting direction so that the braking force generated by the motor may reduce the load lowering speed and may gradually lower the load utilizing its own weight. Also, a mechanism for restraining the rotation in the normal lifting direction, when the chain wheel is under slow speed control, is actuated to restrain the rotation of the air motor, thereby stopping the chain wheel in a safe and sure manner without using a mechanical brake.
    Type: Grant
    Filed: March 5, 1985
    Date of Patent: January 28, 1986
    Assignee: Nippon Pneumatic Manufacturing Co., Ltd.
    Inventors: Yoshiharu Kotone, Masaaki Hiraoka
  • Patent number: 4554997
    Abstract: An improved descent device including a rotating spool on which is wound a cable is provided with a fluid rotation-retarding means having a plurality of vane members mounted for rotation in a fluid-filled chamber. The vane member is comprised of a vane shell receiving a vane core which is normally biassed in a radially inward direction and is extensible from the vane shell by centrifugal force. The retarding force depends on the contact surfaces between the vane members and the fluid which vary with centrifugal force.
    Type: Grant
    Filed: March 7, 1985
    Date of Patent: November 26, 1985
    Inventor: Por-Jiy Sheu
  • Patent number: 4555092
    Abstract: For use in service and maintenance of oil and gas (or water) wells, a system for operating a truck mounted direct drive dual drum winch. Each drum is independently driven by a direct coupled radial piston hydraulic motor. The system includes an improved source of hydraulic power connected to the drum motors through improved piping and valving for selection of drum functions (raise or hoist, lower or drop, or free fall). The system also includes an improved control panel, movable and positionable by the operator for precise and safe control of selected drum functions using pneumatic power.
    Type: Grant
    Filed: May 27, 1983
    Date of Patent: November 26, 1985
    Inventor: Mark Overholt
  • Patent number: 4523664
    Abstract: A portable descent device for lowering an object at a controlled speed has a rotating spool carrying wrapped cable mounted within a casing. The spool rotates about a fixed shaft in a sealed chamber containing a viscous liquid. A series of alternating, closely adjacent, flat, parallel, rotatable and non-rotatable discs are mounted in the sealed chamber and extend radially of the shaft. As cable is payed out from the device, movement of the rotatable discs through the fluid creates a frictional drag which slows the descent rate to a relatively constant, safe speed.
    Type: Grant
    Filed: April 2, 1984
    Date of Patent: June 18, 1985
    Inventors: Garry V. Soubry, James L. MacFarlane
  • Patent number: 4463830
    Abstract: A reel for a life-line comprising a frame, a winding member rotatably journalled in said frame and damping means connected on the one hand with the frame and on the other hand with the winding member for counteracting the rotation of the winding member, said damping means comprising at least two piston pumps axially arranged side by side in a pump housing and cam discs, the cylinder chambers of said piston pumps communicating with one another by an axial channel forming a restriction and the pistons being in contact with the surfaces of the cam discs relatively off-set by half a cam interval, said winding member extending around the damping means, said cam discs being formed by rings and each piston pump being radially arranged inside a ring, while the axial channel is in line with a bore extending from a head face of the pump housing.
    Type: Grant
    Filed: March 9, 1982
    Date of Patent: August 7, 1984
    Assignee: Machinefabriek Geurtsen Deventer B.V.
    Inventor: Alfonsus A. Geurtsen
  • Patent number: 4452430
    Abstract: A safety device for lowering persons and loads comprises a two-piece casing, the two halves of which are symmetrical forming a cylinder therebetween, in which a piston provided with flow channels for a medium is fitted to move axially, the circumference of the piston having a sinusoidal groove in which are engaged one or several pins which are moved by a cable drum which is rotated by the cable around the outer circumference of the cylinder and in which there is a guide roll arrangement for the cable or rope, both ends of the cable hanging freely and one of them being loaded. The arrangement may further comprise three guide rolls with both ends of the cable passing over the central roll on opposite sides of it and then between it and one of the other guide rolls on either side of it, so arranged that the loaded cable presses the central guide roll against the unloaded part of the cable which is thereby pressed against one of the guide rolls producing an additional braking effect by friction.
    Type: Grant
    Filed: February 25, 1982
    Date of Patent: June 5, 1984
    Inventor: Matti K. Kankkunen
  • Patent number: 4438904
    Abstract: Drawworks, having a single outboard brake on the drum shaft at the driller side of the drawworks instead of the pair of brakes conventionally provided at the drum ends, whereby the brake is more readily accessible for service and repairs than are the brakes of conventional apparatuses.
    Type: Grant
    Filed: January 7, 1982
    Date of Patent: March 27, 1984
    Inventor: Bobby E. White
  • Patent number: 4416351
    Abstract: The invention relates to a reel for a life-line comprising a frame, a winding member journalled in said frame so as to be rotatable about a rotary axis, damping means connected on the one hand with the frame and on the other hand with the winding member and counteracting the rotation of the winding member, said damping means comprising at least one cam member and a plurality of piston pumps rotatably co-operating herewith along a relative path of movement with respect to one another and each having a cylinder and a piston displaceable therein and being in contact with the cam member, while of each pair of pumps, whose pistons are moved in opposite senses by the cam member, the cylinders communicate with one another through a channel having a restriction.
    Type: Grant
    Filed: April 15, 1981
    Date of Patent: November 22, 1983
    Assignee: Machinefabriek Geurtsen Deventer B.V.
    Inventor: Alfonsus A. Geurtsen
  • Patent number: 4404891
    Abstract: An improved brake valve for a hydraulically powered winch which has one flow path permitting the relatively unrestricted flow of hydraulic fluid through the valve when the winch is being used to raise a load and a second flow path in which the flow of fluid is controlled in response to the pressure of fluid at the motor inlet when the winch is being used to lower a load. Of particular significance are a fixed area orifice, an annular restrictive passageway and a variable area orifice which cooperate to distribute the pressure drop in the control circuit so as to reduce the sensitivity of the valve to pressure fluctuations in the hydraulic motor circuit. Also of significance are seals used on the spool and damper piston to retard the movement of the spool and to produce a desirable hysteresis effect in its response to pilot pressure.
    Type: Grant
    Filed: August 18, 1980
    Date of Patent: September 20, 1983
    Assignee: Paccar Inc.
    Inventors: Edwin W. Turnquist, Rick J. Bentley
  • Patent number: 4324387
    Abstract: A pressure modulated hydrodynamic retarder is provided for a power delivery system and speed sensing means is provided for sensing the rotational speed of the output of the retarder for producing a corresponding pressure fluid flow which acts to vary the fluid relief pressure of a pressure control valve for the retarder and consequently varies the torque of the retarder in accordance with its rotor speed. In this manner the retarder is modulated as determined by its output speed and when the invention is used in a hoisting operation, as the lowering speed increases due to the falling load the retarding action of the retarder also increases. A particularly desirable form of sensing means includes a variable flow fluid pump which is driven at a speed proportional to the lowering speed of the load to proportionately vary the retarding ability of the retarder.
    Type: Grant
    Filed: January 30, 1980
    Date of Patent: April 13, 1982
    Assignee: Twin Disc, Incorporated
    Inventor: Horst G. Steinhagen