The invention relates to a radial piston pump unit for a high pressure injection system with a pump housing in which a driveshaft with an eccentric section is mounted. A reciprocating ring sits on the above section and drives at least one spring-loaded piston which may be displaced in a direction radial to the drive axis. The driveshaft is embodied to comprise an end region which as a floating mounting and is also the drive for a fuel supply pump.