Abstract: A seal assembly for sealing two relatively movable parts against fluid leakage comprises a seal ring of compressible material mounted on one of the parts, and a supporting ring of non-compressible material positioned in an axial annular groove in said seal ring, said groove being open towards the annular gap to be sealed and surrounded by an annular web, said supporting ring being arranged to be radially displaceable in that groove with limited elastic deformation of said annular web.

Abstract: In a piston diaphragm pump, comprising housing portions clamped together by clamping bolts, a diaphragm, sealingly clamped between adjacent housing portions for separating a feeding chamber from a working chamber, and a reciprocating piston acting in said working chamber filled with hydraulic medium for deflecting the diaphragm to change the volume of the feeding chamber, there is provided at least one supporting member to be screwed to a respective supporting thread in one of said housing portions so as to project towards another housing portion by a distance depending on its screwed position and to abut in the assembled position against an abutment surface on said other housing portion.

Abstract: A piston diaphragm pump includes a support plate, disposed on the side of the piston work chamber, for the diaphragm, which is held in a freely movable manner counter to the pressure of a plurality of springs engaging its circumference. A control push rod under the pressure of another spring, counter to the support plate, engage the circumferential area of the support plate and has a conical recess on its circumference, along which slides a displaceable locking member for a refill valve for the hydraulic fluid during the movement of the control push rod. The refill valve opens only when the support plate displaces the control push rod counter to the pressure of its spring as a consequence of a lack of hydraulic fluid in the pump.