Abstract: A high-pressure water pump of the reciprocating piston type has its metal ston reciprocatable in a cylinder bushing composed of PEEK base high-strength thermoplastic synthetic resin and constructed so as to define a cooling clearance between the piston and the cylinder designed to prevent the temperature of the bushing on continuous operation from rising above 100.degree. C. The piston shoe and the slide bearing for the eccentric shaft should also be a PEEK based resin which can have a filler of carbon fibers, PTFE, glass fibers and/or mineral.

Abstract: The radial piston pump for pumping water, especially pure water, comprises pump housing, a central drive mechanism and a surrounding pump mechanism which has a plurality of piston-and-cylinder units radially oriented and distributed about its circumference. Inlet and outlet valves for individual cylinder chambers are located in the vicinity of the piston-and-cylinder units. The drive mechanism is located in a housing chamber which has an oil sump. The housing chamber is surrounded by a cooling device comprising a plurality of gaps and ducts for conducting water to the inlet valves which are provided with a suction intake fitting for admitting water.