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 double-acting hydraulic pressure intensifier includes a supply connection, a return connection, a high-pressure connection. An intensifier piston assembly includes a low-pressure piston arranged in a low-pressure cylinder and two high-pressure pistons connected to the low-pressure piston each arranged in a high-pressure cylinder. A switching valve assembly includes a displace able, hydraulically controlled valve element which on its two opposite sides in the direction of displacement has control pressure chambers with pressure application areas of different sizes, namely, a first control pressure chamber with a smaller pressure application area and a second control pressure chamber with a larger pressure application area. A stop plug is arranged between the second control pressure chamber and the supply connection.

Abstract: A hydraulic pressure intensifier includes a supply connection, a return connection, and a high-pressure connection. An intensifier piston assembly includes a high-pressure cylinder with a high-pressure piston displaceable therein and a low-pressure cylinder having a greater cross-section than the high-pressure cylinder, with a low-pressure piston which is displaceable therein. The low-pressure piston is connected to the high-pressure piston and divides the low-pressure cylinder into a first low-pressure chamber on the side of the high-pressure piston and a second low-pressure chamber. A switching valve acts on the second low-pressure chamber with pressure from a pressure source or relieves it of pressure.

Abstract: A hydraulic tensioner is designed for low cost and ease of manufacturing. A housing has a bore and a sleeve member received within the bore. A piston is slidably received within the sleeve member, forming a high pressure fluid chamber with the sleeve member. The housing can be constructed of inexpensive materials such as aluminum or plastic. The piston and sleeve member are constructed of drawn metal. The housing may be formed by injection molding. The sleeve member and other components of the tensioner may be assembled within the tensioner by inserting them into the mold during the injection molding process.

Abstract: A pneumatic impacting mechanism comprising a first cylinder and a piston with a rear air distributing bar and a front air distributing bar which simultaneously acts as an impacting head of the same, said rear distributing bar having an axially extending air inlet channel, which in turn can be connected, through a radial air channel in the piston, alternatively with a pair of air inlet channels leading to a second cylinder of a plunger valve, said plunger valve being provided with two annular grooves at both ends for alternatively controlling two air inlet channels and two air exhaust channels. In this manner, the quantities of compressed air entering into the first cylinder during forward and backward strokes are determined by the lengths of the two distributing bars. Moreover, two air buffer chambers are provided at both ends of the first cylinder so that the compressed air doing work within said first cylinder can expand to approximately atmosphere.

Abstract: A hydraulic pressure amplifier, e.g. for generating high water pressure for rock cutting and the like, in which a differentially displaced piston drives plungers alternately to pressurize the water and is driven by a primary fluid under the exclusively of a hydraulically displaceable pilot valve. The valve member is connected by a single pilot passage to the cylinder of the piston for switching between its positions.

Abstract: A hydraulically actuated pumping apparatus including a piston-driven, plunger-type injection pump in combination with a three-way normally closed pilot-operated relay valve, and a variable restrictor adjustable during operation of the pumping apparatus for controlling the flow of a pilot fluid to the relay valve. Pilot fluid is vented from the relay valve through passageways in the plunger of the injection pump at the completion of each pumping stroke.