To prevent wear and seizure by a simple construction to make a high-speed capacity control possible.
At a position which is spaced a distance R apart from the center shaft A of rotation of a swash plate 30 of a swash plate type variable displacement piston pump, and deflected by θ degrees in the reversely tilt-turning direction, a pin member 32 is planted-provided on an end face of the swash plate 30 to form a spherical part 32a on its tip. The nearly central part of one end of a guide rod 41 crossing the axis-line of the pin member 32 at about right angles is pressed against the spherical part 32a by a weak spring 45, and the other end of the guide rod 41 is connected to a core 43 through a connecting rod 42 made of non-magnetic material to build up a differential transformer 44 together with three coil members 44a. Thus, the amount of movement of the pin member 32 is electrically detected through the guide rod 41.
KAWASHIMA KIYOTAKA
ODAJIMA HIROAKI
