Abstract: A rod assembly for a fluid pressure cylinder has a rod member and a packing that is mounted on an outer circumferential part of the rod member and slides along a slide hole. Assembly is simple because a conventional hard piston is not used. The assembly can be carried out simply by hand without the use of a dedicated tool. Thus, the rod assembly simplifies assembly work.

Abstract: An accelerator-equipped pneumatic cylinder includes a cylinder block, a switch valve, and pneumatic cylinder. The cylinder block defines therein a piston chamber and a pressure chamber. The switch valve has a valve seat installed in the cylinder block and between the piston chamber and the pressure chamber. A controller is installed in the valve seat for controlling the piston chamber and the pressure chamber to be communicated with each other or not. The pneumatic cylinder has a piston portion received in the piston chamber, and has a shaft portion extending outward from the cylinder block. At a moment when a channel is made opened by the controller and the piston chamber and the pressure chamber come into communication with each other, the piston portion is pushed by a pressure medium at an accelerated speed, so that the shaft portion is pushed outside the piston chamber at the accelerated speed.

Abstract: A drive unit of a fluid-actuated linear drive includes a piston rod, an annular drive piston seated coaxially on the piston rod and a buffer sleeve which is likewise seated coaxially on the piston rod. These components are secured to one another by one and the same common welded joint. Furthermore, a method for the manufacture of such a drive unit and a fluid-actuated linear drive equipped with such a drive unit is proposed.

Abstract: An electromechanical actuator comprising an electric motor (11) for driving an output shaft (4) in rotation via a reduction gear (20) and passive regulation stage (30) allowing for control of the speed of rotation of the output shaft. A braking member is arranged between an output of the reduction gear and the output shaft to be driven, the braking member being arranged to ensure two different braking levels depending on the direction of rotation of the shaft. The braking member is of hydraulic type and comprises a paddle (33) for transferring fluid between two chambers (34, 35) under the effect of the rotation of the output shaft, transferred fluid passing through a selective drawing member (41) which, depending on the direction of rotation of the actuator, opposes two distinct resistances to the decantation of the fluid from one chamber to the other.

Abstract: A hydraulic cylinder cushion device installed in a hydraulic cylinder provided, in which a rod performs reciprocating movement in a cylinder tube, and which discharges high-pressure hydraulic fluid that is formed in pressure chambers between a piston and a head cover and between the piston and a cover end during a stroke-end operation. The hydraulic cylinder cushion device includes a check ring which is installed in a groove provided on an inner surface of the head cover or the cover end, and moves to one side in the groove so as to close a flow path during rushing into a stroke end while it moves to the other side in the groove so as to open the flow path during an initial operation in the stroke end.

Abstract: A self-adjusting end position damping arrangement includes a stroke space 9 which is delimited by a movable stroke element 7, 24 and a part of the pneumatic cylinder 1, with the stroke space 9 being connected via a connecting duct 14 to the working pressure P1 which acts on the cylinder piston 22 or to the ventilation pressure (P3) in the outlet duct 3 and the stroke element 7, 24 being acted on via a damping duct 16 by the damping pressure P2 in the damping volume 19, a non-return valve 12 is arranged in the connecting duct 14 upstream of the stroke space 9, which non-return valve 12 blocks in the direction of the working pressure P1 or the ventilation pressure (P3), respectively, and a ventilation duct 5 is provided, which ventilation duct 5 can be opened by means of the movable stroke element 7, 24 and which is connected to an outlet duct 3.

Abstract: A hydraulic cylinder cushion including a cylinder having a longitudinal axis and an inner chamber, a piston rod having a base, a cushion spear having a spear base, a shaft extending from the spear base, and a spearhead arranged opposite the spear base, the spearhead comprising a hemispherical portion connected to the shaft, wherein the hemispherical portion is diametrically larger than the shaft, and an end cap having a bore, wherein the end cap is secured to a first end of the cylinder such that the bore faces the inner chamber and is substantially aligned with the longitudinal axis, the piston rod is slidingly arranged within the inner chamber along the longitudinal axis such that the base faces the end cap, the cushion spear is pivotably secured to the base of the piston rod and extends toward the bore, and the bore is adapted to receive the cushion spear therein.

Abstract: A pressure-receiving face plate 29 is mounted on one end face of a piston 12, and a support member 26 is raised on the end face of the piston 12. Disposed on the support member 26 with an allowance are, from the pressure-receiving faceplate 29 respectively, a disk spring 27, a plate 25, and a plunger 28. A flange 26a prevents these members from slipping off the support member 26. When the piston 12 approaches a stroke end, the plunger 28 is inserted in an oil passage 20b and applies a cushioning effect to the piston 12. In addition, a gap between the pressure-receiving faceplate 29 and the plate 25 brought into contact with a cylinder bottom 17 becomes narrow, and produces a squeeze effect such that oil escapes from the narrow gap. This makes it possible to provide a hydraulic cylinder that produces a sufficient impact force at the stroke end of the piston and also reduces noise emitted by the impact force, without increasing a length of the hydraulic cylinder.

Abstract: A cushioned hydraulic cylinder assembly including a hydraulic cylinder having a reciprocating piston movable between an extended position and a retracted position and a hydraulic fluid port proximate an end thereof for ingress and egress of hydraulic fluid. A cushion member is carried by the piston, wherein the cushion member obstructs hydraulic fluid flow out of the port in the retracted position and is spaced from the port in the extended position. A continuous spiral groove is formed in an outer surface of the cushion member and has a beginning at a first end of the cushion member away from the piston and terminates proximate a second end adjacent the piston. The beginning of the spiral groove has a cross-sectional volume, the cross-sectional volume decreasing toward the second end of the cushion member. The spiral groove gradually reduces hydraulic fluid flow out of the port as the piston moves toward the retracted position.

Abstract: Hydraulic actuating device comprising a first and a second hydraulic actuator, which actuators have a first and a second connection for the supply and discharge of hydraulic fluid, which connections are in communication with a first and a second chamber, respectively, by way of a first and a second opening, respectively, in the cylinder space. The first opening of the second hydraulic actuator is in communication with the first opening of the first hydraulic actuator. The second opening of the second hydraulic actuator is in communication with the second opening of the first hydraulic actuator via a third connection. The third connection is in communication with the cylinder space in the first hydraulic actuator via a third opening. Damping means are achieved by a restriction of the outflow of hydraulic fluid via the second opening before the piston/piston rod assembly reaches the second end position.

Abstract: The present invention is directed to a cushioning apparatus for a pneumatic device. The cushioning apparatus generally comprises a body, wherein a piston and cylinder reside therein, wherein the piston is operable to translate along a first axis. A first port associated with a first end of the cylinder is in fluid communication with an interior portion of the cylinder through a first cushioning hole, and a second port associated with a second end of the cylinder is in fluid communication with the interior portion through a second cushioning hole.

Abstract: A variable rate covering system for open top vehicle containers includes a hydraulic actuating system for pivoting arms carrying a roll up cover wherein the fluid flow rates to the hydraulic cylinders are reduced during the initial and final phases of the stroke to reduce acceleration and impact forces on the arms, cover and components, and normal fluid flow rates are provided during central phase movement without significantly affecting overall cycle time. The hydraulic cylinders are provided with metering orifices that reduce fluid flow rates to and from the cylinder pressure chambers for predetermined portions of the stroke length, thereby cushioning the pivoting mechanism at the terminal positions.

Abstract: A pressure medium-actuated working cylinder axially displaceable between two end positions in a cylinder space, with opposite changes in, the volumes of two cylinder chambers on its two sides. A damping element is arranged on one side of a piston. A passage aperture is located between one cylinder chamber and a cylinder connection when the piston runs into one end position forming an annular throttle gap with the passage aperture for outflow of pressure medium. For a high damping capacity, the outer surface of the damping element is shaped to have a maximum diameter at the beginning of the passage aperture and, after a surface section, a small diameter, A middle diameter lies between the maximum diameter and the small diameter.

Abstract: A hydraulic cylinder in which a recess (21) is formed in a piston rod (3) side end surface (20) of a piston (4) so that the recess (21) serves as an axial fitting portion, and an end of the piston rod (3) is fitted into the recess (21) of the piston (4) to ensure the coaxial relationship between the piston rod (3) and the piston (4). Axial threaded holes (24) are formed in an end surface (23) of the piston rod (3) and axial bolt through-holes (25) are formed in the piston (4). The end surface (20) of the piston (4) is disposed in face-to-face contact with the end surface (23) of the piston rod (3), and under the condition bolts (22) are inserted through the bolt through-holes (25) and screwed into the threaded holes (24) to fix the piston (4) to the piston rod (3). Accordingly, the strength of a piston connecting portion can be improved with a simple structure without use of any special high-strength material for the piston rod and without any special heat treatment.

Abstract: An output shaft is connected to a piston rod of a fluid pressure-driven linear cylinder through a converting mechanism for converting linear thrust of the piston rod into rotational torque and converting operation of the converting mechanism is controlled by operation setting means having a cam groove and a cam follower to thereby causing the output shaft to carry out linear motion and swinging rotation. A driving speed of the piston can be changed by adjusting fluid pressure acting on the piston in a linear motion area and a swinging area of the output shaft respectively.

Abstract: A pneumatic cylinder for actuating fume extraction valves in fume and heat extraction plants has a piston (2) that may be actuated from both sides with at least one working surface and that can be made to slide by pressurised air in a cylinder (1) with at least one working chamber (4), as well as an energy accumulator with regulating means. The regulating means can be controlled by control means to open or keep open the fume extraction valves. In order to obtain a compact pneumatic cylinder for a fume and heat extraction plant which is easy to install, a storage chamber in which air or pressurised air is stored as compressible pressure medium is provided as energy accumulator. The storage chamber is in communication with a compression surface (7) of the piston (2), at its side opposite to the working surface (7), so that pressure medium may flow between the storage chamber and the compression surface (7).

Abstract: A pressure medium driven device has a cylinder having a cylinder tube, means forming a discharge outlet for a pressure medium, a piston movable in the cylinder over a stroke having a stroke end which is dampened by a counter pressure generated by throttling the pressure medium within a dampening area prior to its dissipation into the discharge outlet, a piston ring held between the piston end the cylinder in the dampening area and used as a throttle, a dampening sleeve provided in the cylinder for guiding the piston into an end position, the piston ring extending under the action of internal tension beyond a piston diameter and expanding to a maximum internal diameter of a cone, the dampening sleeve having an internal cone causing a progressive dampening, the piston ring having a slit with a minimal width in the cylinder tube, the dampening sleeve being provided in the dampening area with radial boreholes which duct the pressure medium into longitudinal slots from which it reaches the discharge outlet.

Abstract: A cylinder with a speed control mechanism wherein in a transfer stroke, a piston is smoothly accelerated or smoothly decelerated at an initiation or termination end of the stroke by controlling the speed of the piston, whereas in a return stroke, the speed of the piston is not controlled, thereby reducing the time required for the return stroke. A bypass passage bypassing longitudinal grooves for flow control provided on a cushion ring (74) is formed in a passage which provides communication between the outside and a main passage or a cylinder chamber (71, 72). A check valve (78A, 78B) is disposed in the bypass passage to allow a fluid to flow through the bypass passage only during the return stroke of the piston (6).

Abstract: A cushioning system for a fluid power cylinder includes a first passage for the flow of fluid to and from the space between the piston and end cap closure of the cylinder, and a second passage including a throttling valve for throttling the flow of fluid from the space as the piston approaches the end cap closure to cushion the piston. An O-ring seal is centered in the first passage and relative to a seal actuating sleeve on the piston by a plurality of spaced projections extending outwardly from the O-ring. An improved method of forming the valve seat of the throttling valve is also disclosed, wherein the second passage is deformed to substantially conform to the width and shape of the throttling valve and provide substantially zero clearance between the valve and its valve seat.

Abstract: A differential hydraulic jack with a damping system for the control of electric circuit-breakers is provided with a floating ring which produces a damping action at the end of travel and is also provided with a damping extension stud which forms part of the jack piston and penetrates into the damping ring. No provision is made on the jack piston for any packing ring forming a seal with the jack cylinder. The damping ring carries two projecting lips constituting a double valve which forms a leak-tight seal with the bottom face of the jack piston and the internal face of the cylinder end. At the end of the travel of the piston, the damping ring forms a double sealing valve for shutting-off the supply/drain orifice of the jack.

Abstract: The hydraulic crimping tool includes a piston follower mechanism to provide an automatically sequentially reduced crimping force and extent of crimping deformation in predetermined manner in dependence on the extent of travel of a movable crimping jaw toward a stationary jaw.

Abstract: A work cylinder having a piston of single-body construction and a cushioning arrangement integrally formed on the piston includes a cylinder housing having a chamber formed therein divided into first and second work chambers by the piston. First and second piston extensions extend into first and second graduated chamber portions formed at opposite ends of the cylinder housing. A sealing material, bonded to the exterior surface of the piston, exhibits a dual cup-shaped piston seal around the center portion and annular cushion seals on the piston extensions. The cushion seals are at an angle such that, when in contact with a first chamber reduction, a seal results. Additionally, in the opposite direction, the cushion seals act as a check valve whereby fluid pressure introduced to a second chamber reduction depresses the cushion seals and flows into the selected work chamber.

Abstract: A rotary actuator having a piston travel adjustment mechanism and a cushioning mechanism associated in a single attached unit, with side porting for fluid pressure, thus having a more compact structure that is lighter in weight and yet completely adjustable.

Abstract: A fluid-pressure driving device including a main actuator unit having a piston adapted to travel a full part of a predetermined stroke and an accelerating actuator unit having a piston adapted to travel only a part of the stroke and being capable of operating only during the acceleration of the object to be actuated. These actuator units are operated under the control of a control valve such that, in the accelerating range in which the speed of the object is still low, both actuator units operate to produce a large actuating force, while, after the acceleration, only the main actuator unit operates to fully travel the required stroke.

Abstract: The distributor defines two parallel fluid circuits (15, 16) each including serially arranged first (1;1') and second (2;2') valve means actuated by the primary control member (OP) of the distributor, two distribution lines (17, 18) for selectively supplying the chambers of an assistance motor-actuator (12) derivating from said circuits (15, 16) downstream the primary valve means (1;1'), and two additional return valve means (3;3'), upstream said second valve means (2;2') coupled to the piston (13) of the actuator (12) to form a restriction in the return circuit from the actuator chamber in relieved condition and thus create an over-pressure enabling effective return of the actuator to neutral position after return of distributor to rest condition.

Abstract: A shock absorbing device for a hydraulic cylinder including a shock absorbing hole formed in an end wall of cylinder, a passageway having a port opening in the shock absorbing hole at its inner peripheral surface and a shock absorbing member attached to the piston and aligned with the shock absorbing hole so that it enters the hole during shock absorbing stroke. During movement of the shock absorbing member, it throttles the flow of fluid in the hole to perform a first stage shock absorption, then throttles the flow of fluid through the port to perform a second stage shock absorption, and at last compresses the fluid in the bottom of the hole to perform a third stage shock absorption.

Abstract: There is provided a hoist as for an ocean floor dredging operation, which is capable of providing hydraulic heavy lifting capacity, for raising or lowering the dredging means between a surface ship and the ocean floor, and further can routinely provide the ship heave compensation when lifting capacity is not required, for example during dredging operation, or if the raising or lowering of pipe during pipe deployment and retrieval operations is discontinued for any other reasons, such as extremely high seas. The pneumohydraulic system comprises a piston slidably sealably movable within a cylinder and dividing the cylinder into upper and lower portions; a pneumohydraulic accumulator for providing hydraulic fluid to each of the cylinder portions and the necessary valve means to open and close the necessary connections for filling and evacuating one of the cylinder portions with hydraulic fluid without rendering hydraulically inoperative the second portion of the cylinder.

Abstract: A system for resiliently supporting a load at a reference height includes a hydraulic cylinder for resiliently supporting a load about a reference height and an accumulator which cooperates with the cylinder for flowing hydraulic fluid therebetween in response to varying loads imposed on the cylinder. A valve is provided for dampening the rate of fluid flowing between the cylinder and the accumulator and a metering valve coacts with the cylinder for adjusting the reference height about which the load is supported.

Abstract: A poppet valve assembly includes a valving element in the form of a freely slidable poppet, a freely slidable pilot piston having an elongated integral pin extending axially toward the poppet, but unconnected thereto, and an integral elongated spear, with a frustro-conical portion, extending axially in the opposite direction. In a spool valve, the spool is the valving element and has the above elements at each opposite end of the spool, namely a pilot piston with an integral pin unconnected to the spool at the inner end of the pilot piston and an integral spear, with a frustro-conical portion at the outer end of the pilot piston.

Abstract: A synthetic plastic cushion seal for an expansible chamber motor usable with either an air or oil pressurized medium, the seal having reduced friction characteristics, being of a concise configuration and utilizing radial and axial channels to facilitate medium flow during pressurization of the associated motor chamber.

Abstract: A stroke cushioning apparatus for a hydraulic cylinder provided at rod side stroke end and/or head side stroke end. The rod side stroke end cushioning apparatus comprises a sleeve mounted on a piston rod and a cushion ring mounted on the inner face of a housing defining a passage which accommodates the sleeve when a piston assembly is moved to its rod side stroke end. The cushion ring is allowed to move slightly in an axial direction. When the piston assembly is moved towards its rod side stroke end and the sleeve enters into the passage, flow of fluid is restricted between the cushion ring and the sleeve thus effecting a cushioning action to the piston assembly.The head side stroke end cushioning apparatus comprises a plunger mounted to the piston rod and wall of a passage formed at the head end of the cylinder. The plunger is mounted to the piston rod by means of a plurality of balls with allowing slight movements of the plunger both axially and radially.

Abstract: A hydraulic operating apparatus including an actuating cylinder having a piston arranged therein and moved by a fluid under high pressure further includes a control valve having only one metallic seal whether the piston is at its upper or lower positions. The control valve is operative to apply the fluid under high pressure to a pressure receiving surface of the piston on the opposite side of a piston rod to move the piston in a direction in which the piston rod extends from the piston and to discharge the fluid existent on the opposite side of the piston rod from the actuating cylinder to move the piston in a direction opposite the direction in which the piston rod extends from the piston.

Abstract: The disclosure is directed to a hydraulic cylinder with an improved cushion device thereon to enhance the operational characteristics thereof. A cushion pin is affixed to the cylinder piston by a cap screw in such a manner that the cushion pin can float about the screw relative to the piston. Optional orifices in the cushion pin provide an additional fluid flow passage whereby the metering action between the pin and a fluid flow port to the cylinder is different for retraction and extension of the piston.

Abstract: A helical rotary actuator has a torque transmitting section that can be a sealing section or a clearance section but which is welded to a ring gear so that torque forces imposed on the ring gear can be carried through the torque transmitting section to the base of the actuator. In the method of fabrication, the splines on the ring gear are cut after a weldment is made between the ring gear and the torque transmitting section of the cylinder. The pistons within the cylinder are hydraulically cushioned.

Abstract: An expandable cushion plunger for use with a fluid pressure driven piston and cylinder device includes a cushion sleeve mounted on a piston rod in floating relation thereto, and having a skirt, the interior of which is exposed to the cushioning fluid within the cylinder. As the piston nears the end of its stroke, the sleeve begins to enter a fluid exit port, trapping fluid between the piston and the cylinder head, which will slow and cushion the piston travel as it approaches the cylinder head. As the sleeve continues to enter the fluid exit port, the pressure of the trapped fluid increases due to the smaller size of the annular orifice between the sleeve and the port as compared with the port size. The cushion sleeve may expand under influence of increased pressure, further restricting the flow of pressurized fluid through the annular orifice to provide smooth deceleration of the piston as it reaches the end of its stroke and comes to rest against the cylinder head without undesirable impact.

Abstract: A fluid pressure actuator consisting of piston structure reciprocal within a cylinder pressurized through ports at the cylinder ends wherein cushioning means is mounted upon the piston structure controlling the flow of fluid through the ports producing controlled piston deceleration at the termination of its stroke. The port utilizes sealing means in the form of a radially expandable and contractable sealing ring floatably mounted to permit limited radial and axial movement. The seal ring closely engages, in a telescoping manner, the outer cylindrical surface of a valve member mounted upon the piston structure wherein a very accurate and effective seal occurs between the ring and valve member, and bleeding of the cylinder chamber being exhausted can be accurately regulated by predetermined flow control apparatus such as slots, orifices or adjustable needle valves.

Abstract: Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor means cooperating with vent openings to vary venting and thereby vary fluid pressures in the fluid passages.Fluid conduits connect these pressure outputs to a fluid to mechanical translator comprising a double acting piston moving in a cylinder whose opposite ends are connected to the fluid conduits.A receiver is formed by a piston and cylinder or other fluidic motor remotely fluidically connected to the responder, the motor driving a load. Alternatively the remote motor may be omitted, the responder itself constituting a receiver and its piston connected, mechanically or fluidically, to an output display or load for indication or proportional control.

Abstract: An adjustable stroke piston and cylinder combination including a piston fixed to one end of a piston rod that extends from one end of the cylinder, and an auxiliary piston is in sealed engagement with the cylinder means and the piston rod and is slidable on the piston rod, the piston rod is tubular with pressure supply ports therein connecting its bore to a point intermediate the piston and auxiliary piston while a liquid supply means connects to the one end of the cylinder means to supply pressure liquid intermediate the closed end of the cylinder means and the auxiliary piston to move the same axially on the piston rod to control the effective length of the piston stroke in the cylinder means.

Abstract: Cushioning means for cushioning the end portion of the stroke of a piston in a cylinder comprising a stepped cushioning member or spear which enters a cylinder head bore to form therewith an annular orifice which successively decreases in area and gradually increases in radial width from one step to the next thus to decrease piston velocity at substantially uniform rate and, hence, at substantially constant deceleration with substantially constant pressure drop across the annular orifice.

Abstract: The invention is concerned with an improved fluid operated hydraulic ram wherein the travel of the piston thereof is cushioned to reduce impact by progressively restricting fluid flow. The ram of the invention comprises a housing defining a generally cylindrical ram bore having a first wall at a first end thereof with a first hole generally centrally therethrough and a second wall at a second end thereof with a second hole generally centrally therethrough leading to a chamber. A piston fits reciprocally within the ram bore and includes a piston rod extending therefrom through the first hole and a snubber extending from the opposite side thereof towards the second hole. The snubber is sized to pass into the second hole in spaced flow restrictive relation thereto towards the chamber to create a relatively higher pressure in the ram bore adjacent the second end thereof than in the chamber.

Abstract: The invention relates to hydraulic jack operating systems. The end-of-stroke damping of the jack is produced by an element of the shape of a truncated cone, integral with the stem of the jack, which penetrates into a floating ring and which defines, in this ring, a damping chamber isolated from the remainder of the capacity of the jack. When the stem of the jack makes its return movement, the chamber is re-supplied with oil through passages which were previously obturated by the displacement of the ring at the instant of the damping. The invention is applicable to high speed hydraulic controls for circuit breakers with ultra-rapid operation.

Abstract: A fluid actuating device for an electric switching apparatus such as a high-voltage power circuit breaker or the like includes an actuator for actuating the electric switching apparatus. The actuator includes a cylinder and an actuator differential piston movable in the cylinder between first and second positions corresponding to the open and closed positions of the switching apparatus. The actuator differential piston has two end-faces for receiving fluid pressure force and one of the end-faces has a larger surface area than the other one of the end-faces. A pressure fluid supply supplies fluid under pressure and is connected to the actuator for continuously supplying fluid under pressure to the other one of the end-faces. A switching-valve alternately interrupts and connects the fluid from the pressure fluid supply to the one end-face of the actuator differential piston whereby the actuator differential piston is caused to move between its first and second positions.

Abstract: A piston and cylinder actuator is disclosed embodying means to control the acceleration and deceleration of the piston as it approaches the ends of its stroke. Such actuator is also disclosed as an intermittent drive for a machine system in which at least part of the drive connection is provided by a friction drive. The acceleration and deceleration control is arranged to prevent slippage in the drive. The acceleration and deceleration control includes a land positioned on each side of the piston, each formed with a plurality of axially spaced orifices. As the piston approaches one end of its stroke, one land projects through an associated seal which operates to progressively isolate the orifices from the main chamber to control deceleration. Such orifices are progressively uncovered as the piston moves away from its end position, and in one embodiment provides controlled acceleration.

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.

Abstract: Cushioning means for cushioning the end portion of the stroke of a piston in a cylinder comprising a stepped cylindrical member which enters a cylinder head bore to form therewith an annular orifice which successively decreases in area and increases in length thus to decrease piston velocity at substantially uniform rate and, hence, at substantially constant deceleration with substantially constant pressure drop across the annular orifice.