Abstract: An actuator, including a cylinder, an actuator piston displacably arranged in the cylinder, a pressure fluid circuit having a channel mouthing in the cylinder, an indirectly electrically controlled first valve body, arranged in the channel for controlling a flow of a pressure fluid in the channel, and a second valve body, arranged in or at the channel to open and close the channel, the second valve body being a member fixedly connected to the actuator piston, and the first valve body and the second valve body being arranged in series with each other in the channel. The actuator further includes an electrically controlled three-way valve that is arranged to alternately open for a pressure fluid flow from a high pressure source and a pressure fluid flow from a low pressure source, chosen pressure fluid flow being arranged to act against and admit displacement of the first valve body.

Abstract: A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.

Abstract: A linear fluid piston device not requiring a fluid valve to operate and has operating piston stroke capabilities beyond traditional vibration fluid devices. The linear fluid device features (a) a movable piston means for linear motion, (b) a feature wherein said body provides rotational movement for fluid port alignment and a pressure vessel containing an (c) end cap and (d) cavity sized to guide the movable piston. In the improvement, the moveable piston provides a method for changing the linear direction in the event the total linear piston movement has not completed.

Abstract: The invention relates to a reciprocating hydraulic motor having a differential piston interposed between an inlet pipe for fluid at a pressure P1 and an exhaust pipe for fluid at a pressure P2 which is less than the pressure P1 The moving assembly constituted by the different-section pistons that slide in a stepped cylinder includes a flap having two positions and controlling three ports, the flap being mounted to pivot about an axis. In each of its positions, the flap bears against two wall portions disposed on opposite sides of the flap and at different distances from the pivot axis so that the effect of the pressures P1 and P2 on the faces of the flap is to establish a positive closure torque.

Abstract: The device for the compression of a gas comprises a motor (1), a piston (2) adapted to be displaced linearly in a pump body, transmission means (T) between the motor (1) and the piston (2) adapted to convert the rotary motion generated by the motor (1) into a reciprocating translatory motion by the piston (2). Speed varying means comprising a cam (12) are provided to impart a different speed to the piston (2) of the compressor according to the resistance opposing the motor (1) during one complete admission/compression cycle, so that the resisting torque is substantially constant and so that the motor (1) operates at its maximum torque and therefore at maximum efficiency. The section of the cam (12) is determined so as to ensure substantially isothermal compression of the gas.

Abstract: A longitudinally controllable adjustment device comprises a cylindrical housing, in which a piston rod with a piston is slidable and sealingly extending outwards. Furthermore it comprises a valve for controlling length adjustment of the device. In order to avoid a destruction of seals preventing a flow to the outside of pressure medium at least two seals are provided between the housing and the piston rod whereby a seal between the outer end of the housing and a further seal prevents an inflow of gas and in particular of liquid from the outside into the housing.

Abstract: Method and apparatus for recovering leaked fluid or directing fluid flow or propagation through utilization of negative pressure pulses occurring in a pressurized fluid system. The invention has particular application in double acting hydraulic fluid motors where leakage of hydraulic fluid past the output shaft seal may be efficiently collected and redirected into the pressurized hydraulic fluid system through utilization of negative pressure pulses that are developed periodically by fluid direction changes during operation of the hydraulic fluid motor.

Abstract: Disclosed is a device for converting pressure fluid input of one fluid to pressure fluid output of a second fluid without contaminating either fluid. The transformation is accomplished by a unique H section piston which cooperates the internally protruding endcaps enclosed in a double ended cylinder; the piston having a central control valve which reverses the piston on control pin end of stroke contact. Positive reverse action is obtained by means of endcap plungers which operate in response to piston position and pressure of the one fluid. The device is double acting and is enclosed totally within a single cylindrical module which is compact and inexpensive to manufacture.

Abstract: A vibration or reciprocating hydraulically driven impact tool for breaking up paving, compacting soil, or similar construction purposes. The tool employs a piston situated in a housing and configured to form (in cooperation with the housing) three chambers. One of the chambers is filled with a compressed gas which acts as a shock absorber/spring, with the other two chambers serving to drive adjacent flanges of the piston in opposite directions to provide reciprocating action. The device is constructed so that when no mechanical force is applied to the handle, the piston is at rest in its forward position (being urged there by the compressed gas), with the hydraulic forces acting upon the piston shoulders being balanced. When the handle is pushed forward, the hydralic system is altered so that unbalanced forces act on the piston flanges, causing the piston to start moving. Thereafter, a hydraulic valve system provides the desired reciprocating motion of the piston.

Abstract: A vacuum actuator, suitable for use in an automatic belt tensioning system, oscillates automatically when connected to a source of constant vacuum.

Abstract: An improved injector pump (10) is the subject matter of this application. The pump (10) includes a piston (44) freely disposed for reciprocation within a chamber (32). The piston (44) has an aperture (62) extending axially therethrough. A valve member (96) is disposed within the aperture (62) for rotation therein. Means are provided for rotating the valve member (96) between first and second positions, and operating fluid is channeled to opposite sides of the piston (44) depending upon the position of the valve member (96). Means (114, 118, 122, 124) are provided to move the valve member (96) between its first and second positions. Plungers (50, 52) extend in opposite axial directions from the piston (44) to effect pumping of the product fluid.

Abstract: A mechanism for rotating the grab bucket of an excavator is formed with a stator having a shaft extending into the bore of a rotor with hydraulic ducts being provided in the stator and the rotor in flow communication with each other for activating the grab bucket by means of a hydraulic drive mechanism externally connected therewith. The ducts in the stator and the rotor are hydraulically connected by circular passages formed on the outer circumference of the stator shaft and shoulders formed in the rotor and the stator operate to have arranged therebetween bearing means on opposite sides of the circular passages which interconnect the ducts between the stator and the rotor.