Abstract
The influence of the piston rotation on the frictional forces between the piston and the cylinder has been studied experimentally for a swash plate type piston pump and motor. In order to measure the rotational speeds of the piston, the capacitance detecting method have been employed for the piston with the slits. The frictional forces have been measured by means of Piezo-type load washers connecting with the floating cylinder and the rotational speeds of the piston have been measured at the same time. The relations between them are discussed.
