Abstract: A percussive device and method having, inside a machine housing (3), a reciprocally moveable percussive piston (2), the movement of which is controlled by a control valve (5), which is arranged to alternatively connect a chamber to a pressure source and to low pressure in dependence on a signal corresponding to the axial position of the percussive piston, and a valve (16) arranged to allow adjustment of the axial position of the percussive piston at which the signal is transmitted, by opening and blocking of a connection between one or more control channels (10, 11, 12, 13) and the control valve.

Abstract: There is provided a pump system excellent in a maintenance ability and compatibility. The pump system comprises a pump (1) for transferring a liquid by alternately supplying air to air chambers (17a, 17b) to extend and contract a pair of bellows (13a, 13b) linked to a shaft (15). It also comprises a switching valve mechanism (2) for switching the air supplied to the pump (1). Switching mechanisms (40a, 40b) are employed to switch the pilot air for controlling the switching operation of the switching valve mechanism (2). The switching mechanisms are detachably attached to cases (16a, 16b) of the pump (1) from outside.

Abstract: A pneumatic motor having a motor body having a main piston chamber with opposed first and second chamber ends, at least two spool chambers in fluid communication with the main piston chamber, an inlet for flowing a pressurized fluid into each of the at least two spool chambers, and an outlet provided in the housing for exhausting the pressurized fluid from the main piston chamber and each of the spool chambers. At least two spool members are in the two spool chambers, with each spool member adapted to be movable in a first direction to permit pressurized fluid to be supplied to the main piston chamber and also in a second direction to permit the pressurized fluid to be exhausted from the main piston chamber. A piston member is movable in a reciprocating manner in the main piston chamber in response to movement by the spool members.

Abstract: An improved fluid power actuator assembly comprising a power piston reciprocatingly mounted in a cylinder bore which is formed in a compact fluid power manifold providing the necessary circuit connections between control valves mounted on the housing and the cylinder bore. The cylinder bore includes at least two circumferentially spaced signal ports disposed in the wall of the cylinder bore along the path of travel of the piston in addition to the primary power ports located at each end of the cylinder bore to drive the piston. The piston includes at least one circumferential groove and functions as a spool valve for opening and closing communication between the signal ports as the piston travels in the cylinder. Appropriate control valves and signal pressure communicating with the signal ports is disclosed to enable a fluid power signal to be generated which is related to the position of the piston during its travel in the cylinder bore.

Abstract: Control apparatus includes means defining a housing having a hollow and a piston device mounted for reciprocating movement in said hollow under the influence of pressure fluid applied alternately to each of opposite portions of its surface, characterized by means for transmitting a signal of a predetermined travel of said piston in one direction, said signal transmitting means being constructed and arranged to utilize applied pressure fluid in its signalling function.

Abstract: A hydraulic percussion apparatus comprising a body, a cylinder in the body and a percussion piston reciprocating in the cylinder. A distributing valve moves in a valve housing. A valve for starting and stopping the percussion apparatus is provided. A hydraulic pump and hydraulic channels form a percussion circuit with a gas/liquid pressure accumulator. A distributing valve circuit and a free circulation circuit are provided for the pump which are parallelly coupled with the percussion circuit, which circuits are connected to the pump and to the start-and-stop valve which has positions for controlling pressure in the circuits. The start-and-stop valve has a middle position during which pressure in the percussion circuit rises up to a predetermined value while the distributing valve circuit remains closed independent of the pressure in the percussion circuit.

Abstract: A reciprocating pump for liquids has a shuttle valve for directing motive fluid alternatively to small- and large-area faces of a piston. The motive fluid directed to the small-area face acts as a spring for causing reciprocation.

Abstract: An hydraulically operated striking apparatus for driving a rock drill or the like comprises a body having an axial, generally cylindrical, interior space with an inwardly protruding annular member. A cylindrical piston is positioned in the space in sliding contact with the protruding annular member, and the piston has canal means in its outer surface. The body, the annular member and the piston define two annular spaces and an annular distributing valve is slidably disposed within one of the spaces. The two spaces communicate with each other by means of the piston canal when the piston is in a first slidable position, and the protruding annular member prevents communication between the two spaces when the piston is in a second slidable position. The piston is provided with an axially disposed extension which, in combination with an outlet means, serves to permit a third, annular axial space to communicate with either an inlet means or an outlet means at all times.

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.