Abstract: An improved pneumatic piston apparatus is provided wherein a movable poppet valve member employs at least one composite member exposed to air pressure which varies dynamically during the operation of the apparatus. Delamination of the composite member and resultant malfunction of the poppet valve are avoided by a novel construction in accordance with the principles of the present invention, which excludes the dynamically varying air pressure from access to the interface between the layers of the separate materials comprising the composite member. The effect achieved by the novel construction is further enhanced by the manner in which the composite member is retained on the poppet valve member. Unwanted movement of the piston conjointly with the motion of the poppet valve member is precluded in the invention by providing an air space therebetween.

Abstract: The piston of a hydraulic cylinder is provided with a corrugated running surface composed of angularly disposed ribs and valleys therebetween, the ribs bearing against the relatively smooth bore of the tubular casing in which the piston reciprocates. Whereas the ribs on the piston provide a corrugated running surface bearing against the bore, the cylinder head, in which the piston rod is journaled, is formed with a similarly corrugated running surface.

Abstract: A driving assembly for moving one unit with respect to another, for instance, a working unit with respect to a frame unit. Preferred practical applications for the driving assembly are lifting platforms or presses. The driving assembly includes a flat, enclosed, flexible container or bladder disposed between the two units. End wall portions of the container comprise the major surface area thereof. When pressure is introduced into the container, the walls thereof bear entirely against opposed bearing portions of the respective units and against a limiting wall. The invention allows for use of a very thin walled container for lifting large loads.

Abstract: A power steering system has a valve between the pump and steering unit. The valve maintains a constant pressure differential so that the pump is unable to deliver aerated fluid to the unit in the event of loss of fluid or fracture of a pipe.

Abstract: A hammer and more particularly a fluid operable hammer wherein alternating impetus provided by pressurized liquid and gas means actuates a reciprocable hammer piston to generate repetitive impact loads.

Abstract: This invention relates to a hydropneumatic valve actuator comprising an outer cylindrical casing and an inner cylindrical casing both having closure means at each end. The inner cylindrical casing is positioned in said outer casing and is transversely spaced therefrom to define an elongated annular gas chamber. A piston slidably mounted in said inner casing has a piston rod extending axially from one end thereof through an axial bore in one of said closure means. The gas chamber as well as the portion of the inner casing between the piston and the other closure means, are adapted to be charged with gas under pressure and the portion of the inner casing between the piston and the closure means through which the piston rod extends is adapted to be charged with liquid.The piston is provided with a pair of spaced annular seals and means are provided to prevent gas leakage past one of the seals into the portion of the inner casing charged with oil under pressure and to sense leakage of oil past the other seal.