Abstract: The invention is based on a reciprocating piston pump having two radial pistons disposed symmetrically to one another, which are drivable to a reciprocating motion by an eccentric disposed between them and are held in contact with the eccentric by a hoop spring that engages the pistons. For ease of installation, the invention proposes embodying the hoop spring as a bent wire part, with two open, hooklike eyelets on their ends, which ends are inserted into annular grooves of the pistons and enter into a snap connection with them in order to hold the pistons tightly against the eccentric.

Abstract: A feed pump for a hydraulic system that is equipped with at least one outlet valve whose valve-closing body is loaded by a valve spring. The valve-closing body is held at a distance form its valve seat by means of a gas-filled hollow-body ring so that the feed pump can be evacuated through its outlet valve for subsequent filling with a hydraulic pressure medium. With a first increase in pressure in the system, the hollow-body ring is pressed together, so that the valve-closing body slips through the hollow-body ring and reaches its valve seat, thus making the outlet valve operational. The feed pump is suitable for use as a return pump for anti-skid systems of hydraulic brake systems.