Fluid Spring Patents (Class 92/85B)
  • Patent number: 4269283
    Abstract: This invention has for its object to eliminate the problem of loud noise and violent vibrations in machines having transient force characteristics of the type appearing in punching or cutting presses.According to the invention this is achieved by means of a damping device comprising a housing defining a chamber filled with a hydraulic fluid said fluid being pre-compressed by a first piston acted on by the force and said pre-compressing being carried out to a pressure corresponding the force to be dampened. Immediately before the force relief the force is arranged to act on a second piston of bigger cross sectional area said second piston preventing a too rapid force relief of the press frame due to the pre-compressed hydraulic fluid.The force relief occurs rather slowly due to the fact that the hydraulic fluid trapped in the chamber is exhausted via control valve keeping the pressure in the chamber almost constant and only permitting a certain volume flow therefrom.
    Type: Grant
    Filed: October 4, 1979
    Date of Patent: May 26, 1981
    Assignee: Hakan Sallander
    Inventors: Bo C. Bramberger, Kurt G. Stenudd
  • Patent number: 4257314
    Abstract: An improved type of hydraulic control cartridge with mounting structure and accessorial safety device for installation within both ends of reciprocative pneumatic actuators to permit a safe increase in their speed of operation. The safety device automatically stops the actuator if the hydraulic cartridge malfunctions.
    Type: Grant
    Filed: October 24, 1978
    Date of Patent: March 24, 1981
    Inventor: Richard E. Deschner
  • Patent number: 4255930
    Abstract: A closed circuit power system is disclosed herein having a hydraulic power device incorporated therein which includes an input piston and cylinder assemblage and an output piston and cylinder assemblage connected together by a fluid conduit so as to operate in unison. The input assemblage includes a piston moved by an input ram so as to apply a fluid pressure via the conduit to the output assemblage. The output assemblage includes a pair of pistons operating in unison in separate chambers in response to the applied fluid pressure for moving an output shaft. The pair of pistons include pressure faces against which the fluid pressure is applied which are of equal area but different shape. A selected piston of the output assemblage includes conical forward and rearward faces with a corresponding or matching concave recess in the rear cylinder wall.
    Type: Grant
    Filed: August 10, 1979
    Date of Patent: March 17, 1981
    Inventor: Adam J. Natalie
  • Patent number: 4250793
    Abstract: A fluid jack (10) has a cushioning device (21) positioned within a cylinder (11) between a piston means (12) and a closed end (13) with the cushioning device (21) being a self-contained unit independent of any major components of the fluid jack (10). A variable volume chamber (24) is formed between a pair of members (22,23) with the cushioning taking place by metering the fluid expelled from the variable volume chamber (24) in response to the piston means (12) engaging and moving one of the members (22,23) in a direction for decreasing the volume of the variable volume chamber (24).
    Type: Grant
    Filed: November 20, 1978
    Date of Patent: February 17, 1981
    Assignee: Caterpillar Tractor Co.
    Inventor: Lawrance F. Berg
  • Patent number: 4240332
    Abstract: A fluid pressure actuator which locks in the extended position. The lock is a roller operated, dual segment pawl mechanism that unlocks in response to a pressure difference between extend and retract pressures. The two lock segments, chamfered for engagement with the cylinder end, are in diametrically opposed slots in the actuator piston head. A cylindrical section projects from the segment portion. An end view of the lock is mushroom shaped. Two rollers, held in alignment normal to the actuator centerline by a cage integral with the unlock rod, operate in conjunction with the lock cam surfaces in such a manner as to carry the radial loading imposed when in the lock mode.In operation, when the actuator is driven to its extreme extend position, the pawls are driven out by the rollers and lock against the cylinder end. The linear force on the rollers is due to the preload spring plus the hydraulic pressure differential (extend pressure greater than retract pressure).
    Type: Grant
    Filed: August 25, 1978
    Date of Patent: December 23, 1980
    Assignee: Arkwin Industries, Inc.
    Inventor: Edward J. Deutsch
  • Patent number: 4230019
    Abstract: A fluid arrangement for the alternating operation of an apparatus includes a working cylinder with a working piston endowed with an alternating movement and a control cylinder with an alternatingly moving control piston. Each of the cylinders has for the respective piston a driving chamber which is alternately connected to a supply source of fluid under pressure and to a discharge opening for the fluid through a distributor, and a return chamber permanently connected to the supply source of fluid under pressure. The distributor connected to the driving chamber in the working cylinder is the control cylinder, and the distributor connected to the driving chamber in the control cylinder is the working chamber.
    Type: Grant
    Filed: November 13, 1978
    Date of Patent: October 28, 1980
    Inventor: Luis M. Castejon Castan
  • Patent number: 4210064
    Abstract: Method and device for braking the speed of movement of the piston of a plunger-cylinder device by choking the outlet of medium on the side of the piston approaching the end wall of the cylinder and by coupling the piston rod of the cylinder with the piston of a second plunger-cylinder device.
    Type: Grant
    Filed: January 10, 1978
    Date of Patent: July 1, 1980
    Assignee: Hydraudyne B.V.
    Inventor: Josephus J. Beerens
  • Patent number: 4208879
    Abstract: In an injection molding machine of the type comprising an injection cylinder, a feedback circuit for feeding back the oil in the rear chamber of the injection cylinder into the front chamber thereof and a booster cylinder, a pressure oil accumulator is connected to the booster cylinder through a valve for supplying pressurized oil for actuating the booster cylinder. A check valve is connected in parallel with the valve. When water hammer occurs at the end of the injection stroke the check valve opens to absorb the energy of water hammer by the accumulator.
    Type: Grant
    Filed: February 10, 1978
    Date of Patent: June 24, 1980
    Assignee: Toshiba Kikai Kabushiki Kaisha
    Inventor: Kazuyoshi Segawa
  • Patent number: 4206687
    Abstract: The invention relates to a cushioning device for a piston of a pneumatically operable driving tool which includes a cylinder, wherein a drive piston connected to a driver blade is axially movable; including further a bumper at the lower end of the cylinder and an annular chamber connected to a fluid power reservoir; this chamber is located underneath the piston and is surrounding the driver blade. The annular chamber, created by the piston and a wall, generally parallel to the face of the piston, will be reduced in volume to a certain extent when the wall impacts on the bumper to reduce the noise generated during the driving action.
    Type: Grant
    Filed: June 7, 1978
    Date of Patent: June 10, 1980
    Assignee: Signode Corporation
    Inventors: Arthur Klaus, Horst Tacke
  • Patent number: 4203350
    Abstract: A hydraulic percussive machine comprising a piston and cylinder with a dashpot at the front end to cushion overtravel of the piston. Heat is removed from the dashpot by admitting pressure fluid to the return stroke chamber through a front chamber and the dashpot. On the pressure stroke fluid from the return stroke chamber is admitted to the working stroke chamber in one case by causing all flow to take place along that route and in the other place by having two feeds to the working stroke chamber with a flow restrictor in the direct feed line.
    Type: Grant
    Filed: February 28, 1978
    Date of Patent: May 20, 1980
    Assignee: The Steel Engineering Company Limited
    Inventor: Trevor E. Wallace
  • Patent number: 4203501
    Abstract: This device comprises two movable elements of rigid material tightly interconnected by means of a deformable membrane forming therewith a tight internal enclosure, means for varying abruptly the volume of said enclosure by successively moving the two elements away from each other, maintaining them in spaced relationship and allowing them to be urged toward each other by the effect of the external hydrostatic pressure, in which the means for moving the two elements away from each other includes two cylinders and at least one piston slidable in one of said cylinders, associated to one of said movable elements and also to a push-member slidable in one of the cylinders and bearing on the other movable element and means for feeding said cylinder with pressurized fluid so as to maintain the elements in spaced relationship or to release them.
    Type: Grant
    Filed: May 9, 1978
    Date of Patent: May 20, 1980
    Assignee: Institute Francais du Petrole
    Inventors: Jacques Cholet, Jean Laurent, Pierre Magneville, Claude Duconge
  • Patent number: 4190230
    Abstract: A scavenging air valve for cleaning at least one tubular filter body is disclosed. The air valve has a laminar valve body, one side of which forms, by means of its inner portion, the shutoff for the inlet of a scavenging air line. Its edge zones of said one side face toward a scavenging air chamber. The valve body is movable perpendicular to the side mentioned, inside of a maintaining chamber, under the effect of the scavenging air. The maintaining chamber is, on the one hand, in constant communication with the scavenging air chamber over at least one throttling point and, on the other hand, is connected to a blockable exhaust air line through means of a control valve.
    Type: Grant
    Filed: March 10, 1978
    Date of Patent: February 26, 1980
    Assignee: Gebrueder Buehler AG
    Inventor: Hans Geissbuhler
  • Patent number: 4179983
    Abstract: A hydraulic percussive machine in which a piston is caused to reciprocate in a cylinder including a cushioning flange on the piston, a first space in which the flange normally moves, a second space into which the flange can move on overtravel of the piston during the power stroke to trap fluid into the second space so that a dashpot action takes place, and co-operating timing grooves and ports on the piston and the cylinder to connect the first space to a low pressure zone in the system.
    Type: Grant
    Filed: March 9, 1977
    Date of Patent: December 25, 1979
    Assignee: The Steel Engineering Company Limited
    Inventor: Trevor E. Wallace
  • Patent number: 4175914
    Abstract: This automatic hydraulic cushioning device for cam plate positioning actuators on variable displacement, axial piston pumps eliminates the noise, vibration, and wear caused by hammering of the positioning actuator on the back plate when the actuator is close to full retraction. A supply of fluid under pressure, which is available at the back plate, is channeled to the cam plate positioning actuator. A valve in the actuator blocks off drainage of the fluid whenever the actuator is close to its fully retracted position. This retained fluid becomes a hydraulic stop and cushion for the actuator thus eliminating the hammering as well as the noise, vibration, and wear which results from the hammering.
    Type: Grant
    Filed: May 31, 1977
    Date of Patent: November 27, 1979
    Assignee: The Cessna Aircraft Company
    Inventors: Dennis R. Unruh, Robert J. Martin
  • Patent number: 4167134
    Abstract: A compact, double-acting piston-type fluid activated device having an axially reciprocable piston for controlled, predetermined deceleration of the piston as it approaches the limit at each end of its travel within a cylindrical bore. The cylindrical bore is sealed at each end by end walls removably retained in the bore. Each end wall is provided with a central counterbore in its inner surface which in cooperation with the piston provides a cushioning chamber. The area of the counterbore central surface is critically related to the circular cross-sectional area of the cylindrical bore in which the end wall is to be secured, being in the range from about 60% to about 85% thereof. A vent passage places the cushioning chamber in preselectedly restricted flow communication with porting means in the wall of the device, each port being located intermediate the end walls. A method is provided for removably circumferentially locking each end wall in the operating cylinder with a wire snap ring having a hooked end.
    Type: Grant
    Filed: February 28, 1977
    Date of Patent: September 11, 1979
    Inventor: Lawrence F. Yuda
  • Patent number: 4111311
    Abstract: A material handling unit for moving material from one position to another comprises a gripper arm on a shaft which is movable critically by fluid pressure and is rotatable by a rack and pinion mechanism actuated by a cylinder and piston. Adjustable abutments are provided for limiting the range of movement of the arm. Dashpot means for applying a damping force to the manipulator so as to decelerate it before it reaches the limit of its movement is adjustable both as to the range of action and the rate of deceleration.
    Type: Grant
    Filed: September 17, 1976
    Date of Patent: September 5, 1978
    Assignee: Kabushiki Kaisha Daini Seikosha
    Inventor: Hideo Hirama
  • Patent number: 4073350
    Abstract: A recoil damping device for a percussion tool in which the recoils are damped by means of a pressurized hydraulic fluid entrapped in the machine housing.
    Type: Grant
    Filed: March 8, 1976
    Date of Patent: February 14, 1978
    Assignee: Atlas Copco Aktiebolag
    Inventors: Ake T. Eklof, Per T. A. Fengsborn, Gunnar V. R. Romell
  • Patent number: 4068727
    Abstract: A recoil damping device for a percussive tool comprises a retard piston which is movable in a cushioning chamber. The feeding force and/or the pressure in the supply passage to the cushioning chamber is regulated so that the retard piston is axially free relative to the machine housing.
    Type: Grant
    Filed: March 10, 1976
    Date of Patent: January 17, 1978
    Assignee: Atlas Copco Aktiebolag
    Inventors: Kurt Holger Andersson, Carl Gosta Bernhard Ekwall, Bo Erik Forsberg
  • Patent number: 4067667
    Abstract: A compressor of the free-piston resonant type driven by an electrodynamic oscillating motor incorporates means to control the stroke to allow for stable operation over a wide range of operating conditions. The spring-mass system of the compressor which is forced into vibration by the electrodynamic oscillating motor is arranged to have a selectively variable natural resonant frequency generally centered on the power line frequency. Variable area port means responsive to any overstroking are operative to vary the natural frequency of the spring-mass system by varying the stiffness of a gas spring means thereof so as to oppose overstroking and also provide for a maximum stroke limit.
    Type: Grant
    Filed: February 9, 1976
    Date of Patent: January 10, 1978
    Assignee: Mechanical Technology Incorporated
    Inventor: Harlan Vernon White
  • Patent number: 4048905
    Abstract: This invention is a piston-cylinder hydraulic snubbing device to arrest or resist motion. The invention may be utilized as a snubbing device alone, or it may be incorporated into a hydraulically actuated piston-cylinder assembly. The principal feature is that an orifice, through which hydraulic fluid is forced, is in the form of a gap between the ends of a piston ring, which gap is varied by engagement of the ring with a tapered bore in the cylinder.
    Type: Grant
    Filed: March 29, 1976
    Date of Patent: September 20, 1977
    Assignee: The Boeing Company
    Inventor: Richard Ervin Souslin
  • Patent number: 4043254
    Abstract: An apparatus for hydraulically cushioning the motion of reciprocating means is provided by first hydraulic cushioning means which is adapted to be contacted by the reciprocating means near the end of its stroke in the direction of the first hydraulic cushioning means, second hydraulic cushioning means adapted to be contacted by the reciprocating means near the end of its stroke in the direction of the second hydraulic cushioning means, and means for adjusting the position at which the reciprocating means contacts at least one of said first and second hydraulic cushioning means.
    Type: Grant
    Filed: December 3, 1974
    Date of Patent: August 23, 1977
    Assignee: Emhart Industries, Inc.
    Inventor: Eginhard Jaeger
  • Patent number: 4041845
    Abstract: Hydraulic elevator apparatus including a cylinder and a fluid actuated plunger which supports an elevator car. A cylinder head seals against fluid leakage to the outside, and it guides the plunger as it moves relative to the cylinder. The cylinder head includes a travel limit structure for the plunger which generates a hydraulic retarding force programmed by a resilient device which adjusts the hydraulic retarding force during a travel limit stop. The resilient device also adds its own retarding force to the plunger, to smoothly decelerate and stop the plunger with minimal impact forces on the cylinder head.
    Type: Grant
    Filed: November 20, 1975
    Date of Patent: August 16, 1977
    Assignee: Westinghouse Electric Corporation
    Inventors: Jean-Marie L. Mean, Joseph K. Kraft, Leigh F. Jackson
  • Patent number: 4034958
    Abstract: A device for opening and closing a rotary valve by remote control comprising a cylinder having a main bore in which a movable unit is slidably mounted in fluid tight manner and which can be displaced in opposite directions by a pressurized fluid supplied by either of two pressurized fluid sources which can be remotely actuated in independent fashion. A sequencing mechanism is mounted in the cylinder for simultaneously applying the pressurized fluid from an activated source to a corresponding end face of the movable unit while connecting the other end face with the atmosphere. The movement of the slidable unit is transmitted to the rotary valve through a rack and pinion arrangement and a linkage composed of cranks and a connecting rod so arranged that when the valve is in either of its end positions it cannot produce movement of the linkage due to alignment of the axis of rotation of the pinion and the connection points of the rod to the cranks.
    Type: Grant
    Filed: May 6, 1975
    Date of Patent: July 12, 1977
    Assignee: Messier Hispano
    Inventor: Jean Masclet
  • Patent number: 4026192
    Abstract: A motor driven by a pressurized fluid medium for operating an impact tool in a linear direction adapted for metal stamping and high velocity milling comprising a housing and a piston unit. The latter comprises a drive piston, a piston rod and a tool. In addition, the motor includes a kinetic energy absorbing device comprising a hydraulic fluid chamber and a retard piston which is rigidly connected to said piston unit and arranged to reciprocate in said fluid chamber. The retard piston retards the piston unit at the end of the strokes only and is freely passed by hydraulic fluid during the working stroke. Cup-shaped means are provided to restrict said by-pass flow of hydraulic fluid at the end of the strokes and thereby protect the motor from excessive stresses during no-load conditions.
    Type: Grant
    Filed: May 17, 1974
    Date of Patent: May 31, 1977
    Assignee: Atlas Copco Aktiebolag
    Inventors: Carl Anders Noren, Bertil Waldemar Sundin
  • Patent number: 4020747
    Abstract: A hydraulically-operated reciprocatory device such as a road-breaking hammer includes piston means having an enlarged area portion which enters an overtravel-damping dashpot cavity. The dashpot cavity is in a chamber connected in series with valve means controlling the flow of hydraulic fluid such that said fluid flow through the chamber removes heat generated during a damping action.
    Type: Grant
    Filed: November 27, 1974
    Date of Patent: May 3, 1977
    Assignee: A. F. Hydraulics Limited
    Inventor: Lionel Arthur Reynolds
  • Patent number: 4021151
    Abstract: An electric motor driven compressor includes a reciprocating free-stroke armature driving a compressor piston in a cylinder. A cylinder head closes the cylinder to form a compression chamber into which opens an intake passage and an output passage selectively closed by valves. The output passage provides an opening into the compression chamber through the cylinder wall at a selected distance from the cylinder head to provide an energy absorbing chamber filled with gas when the piston closes the opening of the output passage during its compression stroke. The energy absorbing gas cushion in the chamber prevents impacts between the piston and cylinder head under varying operating conditions.
    Type: Grant
    Filed: June 10, 1975
    Date of Patent: May 3, 1977
    Inventor: Maurice Barthalon
  • Patent number: 4018135
    Abstract: A hydraulic impact device has a hammer member carrying a piston which is reciprocally disposed in a cylinder chamber to form an expansible chamber. When the expansible chamber is pressurized, the hammer is retracted against an air spring or other energy storage device by the high pressure. A sleeve valve is reciprocally disposed in the cylinder chamber between the piston and the energy storage device and is held against the piston by an imbalanced fluid pressure as the hammer is retracted against the spring. When the piston and sleeve valve have been retracted to a predetermined position, high pressure fluid is ported between the sleeve valve and piston to hydraulically separate the two members.
    Type: Grant
    Filed: December 26, 1973
    Date of Patent: April 19, 1977
    Assignee: Construction Technology, Inc.
    Inventors: Raymond E. Lance, Ronald N. James
  • Patent number: 4015728
    Abstract: An improved hydraulic actuator for use as a swing motor in a material handling apparatus of the type having a vehicle mounted boom. Two embodiments are disclosed and each includes a vertically disposed, double-acting cylinder having an internal, vertically reciprocal piston. The cylinder may be disposed between yoke arms mounting a boom and provision is made for securing the cylinder to the vehicle frame. A coupling device is secured to one of the yoke arms and has a first splined surface while means are carried by the piston and movable therewith and include a second splined surface slidably engaging the first splined surface.
    Type: Grant
    Filed: February 24, 1975
    Date of Patent: April 5, 1977
    Assignee: Caterpillar Tractor Co.
    Inventors: Noble G. Barker, John E. Corwin, Jimmy D. Myers, Jan B. Yates
  • Patent number: 4013385
    Abstract: A deep well pump system incorporating a sub-surface pump unit and a surface power unit with a fluid column formed therebetween. The pump unit incorporates a counterbalance means that is specifically illustrated as a collapsible volume chamber operably engaged with a pump piston to cause a fluid pumping linear movement of the piston responsive to the selective contraction and expansion of the collapsible volume chamber. The power unit, in the charging stroke thereof, pressurizes the fluid column by the introduction of a volume therein sufficient to contract the collapsible volume chamber, with a subsequent pressure buildup effecting discharge of additional fluid from the power unit with less valving than the prior art pumps.
    Type: Grant
    Filed: June 6, 1975
    Date of Patent: March 22, 1977
    Inventor: Fred M. Peterson
  • Patent number: 4006666
    Abstract: A cushioning device, for cushioning the impact between a closed end portion of a cylindrical member of a hydraulic jack and an end portion of an inner member reciprocable within the cylindrical member, including a blind bore provided in one of the end portions, an elongated plunger attached to the other end portion for telescopic entrance into the blind bore as the end portions approach each other and an orifice for metering fluid forced from the blind bore by the progressive ingress of the plunger into the bore.
    Type: Grant
    Filed: May 22, 1975
    Date of Patent: February 8, 1977
    Assignee: Towmotor Corporation
    Inventor: Kenneth R. Murray
  • Patent number: 3992978
    Abstract: A pressure balanced hydrostatic slip bearing as shown for use in guiding and restraining a test table which is shaken in longitudinal direction to vibrate or shake test objects, and also which may be shaken in vertical direction. The slip bearing controls lateral position of the table during operation. A second slip bearing applies a constant compressive preload force to one side of the table and the other pressure balanced bearing is a constant displacement bearing positioned on an opposite side of the table to react lateral forces which may be imposed on the table during operation.
    Type: Grant
    Filed: June 23, 1975
    Date of Patent: November 23, 1976
    Assignee: MTS Systems Corporation
    Inventor: Niel R. Petersen
  • Patent number: 3990351
    Abstract: A pneumatic impact device comprising a housing, a drive piston and a piston rod. At the forward end of the piston rod there is attached a tool intended for metal working like punching, cropping or forging. The housing contains a drive chamber, an air charge chamber, a reverse chamber and a retard chamber. The piston rod is provided with two forward-facing, annular shoulders one of which constitutes a reverse piston for working in the reverse chamber and the other a retard piston for working in the retard chamber. For being protected from impact strains, the drive piston is longitudinally displaceable relative to the piston rod. During the working strokes, the drive piston cooperates with a backwardly facing shoulder on the piston rod, but just before the latter reaches the point where the tool hits the billet to be worked, the drive piston is stopped in the drive chamber and is thereby separated from the piston rod shoulder.
    Type: Grant
    Filed: December 5, 1974
    Date of Patent: November 9, 1976
    Assignee: Atlas Copco Aktiebolag
    Inventor: Bertil Waldemar Sundin
  • Patent number: 3973468
    Abstract: An extendible and contractible shaft comprises a number of shaft members on a common longitudinal axis, each except the outermost member being telescoped within the one next adjacent. Each telescoped member has a piston slidably sealed to the inner wall of the next adjacent outer member to form a series of tandem arranged sealed pistons. Fluid passageways are provided between adjacent shaft members so that fluid supplied under pressure to an inlet port of the device flows through the passageways to all the piston heads, thereby extending the telescoped shaft members and at the same time driving fluid out from under each piston through fluid passageways to an exit port of the device. When the pressurized fluid flow is reversed to send pressurized fluid to the undersides of the pistons, thereby driving fluid above the piston heads out through the first mentioned port, there would normally be incurred substantial shock as each piston head strikes its stop in the retraction operation.
    Type: Grant
    Filed: August 2, 1974
    Date of Patent: August 10, 1976
    Inventor: Wayne B. Russell, Jr.
  • Patent number: 3969990
    Abstract: A miniature piston assembly composed of an elongated cylinder containing a piston head which may be displaced in response to digital hydraulic signals or otherwise and which is arranged to provide self-snubbing without requiring check valves. In the side wall of the cylinder are one or more ports spaced from one or more of the distal ends of the cylinder by a predetermined distance. When the piston is in juxtaposition with a port and approaching the proximate end of the cylinder, the cylinder and the piston define an annular clearance space of ever increasing length and fluid impedance for snubbing the motion of the piston with respect to the cylinder.
    Type: Grant
    Filed: August 2, 1974
    Date of Patent: July 20, 1976
    Assignee: International Business Machines Corporation
    Inventors: Bayard G. Gardineer, Hugh A. Panissidi
  • Patent number: 3967542
    Abstract: A hydraulic intensifier for oil well fracturing and/or erosion drilling incorporates a pair of intensifier units mounted on a common bed. The intensifier units are particularly defined for ease of maintenance in the field, and structure is provided by which the ram seals as well as the ram, the ram cylinder, and the hydraulic cylinder can be easily and readily removed in the field without the necessity for releasing the tension on the tie rods. To this end, the apparatus includes a front wall which supports the ram cylinder and an intermediate wall which supports the forward end of the hydraulic cylinder. The space between these walls and the manner in which the components are assembled permits the ram seal assembly, the ram and ram cylinder, and hydraulic piston to be extracted and reinserted. Also, an improved ram return system and a hydraulic cushioning system are disclosed.
    Type: Grant
    Filed: November 20, 1974
    Date of Patent: July 6, 1976
    Assignee: Kelsey-Hayes Company
    Inventors: Richard W. Hall, Daniel A. Schutte, Sven Sonnenberg
  • Patent number: 3955478
    Abstract: The improved hydraulically actuated percussion drill described hereinafter is designed to reciprocate a striker piston contained therein regardless of whether or not the striker piston engages the drill steel whereby vibration can be imparted to the drill. The drill includes an overtravel portion that cooperates with the striker piston to prevent metal-to-metal contact of the striker piston with the housing during operation. Means are provided to prevent the loss of fluid from the overtravel chamber whereby the striker piston will be returned to the upper end of its stroke and will not become stalled in the overtravel chamber.
    Type: Grant
    Filed: October 29, 1973
    Date of Patent: May 11, 1976
    Assignee: Dresser Industries, Inc.
    Inventor: Jacob Edward Feucht