Abstract: In an eccentric radial piston pump, a rib 12 protruded in a radial direction is formed on an inner peripheral surface of an end portion on a discharge side of an eccentric cam ring 3 over a prescribed range. In an eccentric radial piston motor, a rib 12 protruded in a radial direction is formed on an inner peripheral surface of an end portion on a high pressure side of an eccentric cam ring 3 over a prescribed range. By the rib 12 formed in the radial direction, a rigidity of the eccentric cam ring 3 can be improved, and the eccentric cam ring can be prevented from being deformed by a thrust from the piston. Thus, the rigidity of the eccentric cam ring can be increased without increasing the thickness of the eccentric cam ring, and further the eccentric radial piston pump and the eccentric radial piston motor in which outside dimensions in the radial direction are reduced can be provided.

Abstract: A capacity control apparatus for a variable capacity hydraulic pump including: a capacity control cylinder having a capacity control piston for driving a capacity control member of the hydraulic pump, with a large diameter chamber and a small diameter chamber disposed at both sides of the capacity control piston, and driving the capacity control piston with a pressure fluid that is supplied into the larger diameter chamber, in a direction in which the capacity of the hydraulic pump may be reduced and for driving the capacity control piston with a pressure fluid that is supplied into the small diameter chamber, in a direction in which the capacity may be increased; a passage for the small diameter chamber to communicate with a pump discharge path; at least one control valve for controlling the capacity of the hydraulic pump by selectively communicating the large diameter chamber with either a pump pressure discharge path and a reservoir; and a variable throttle valve in a passage with the at least one control

Abstract: A displacement controlling circuit system for a variable displacement pump, which system permits, following high or low rates of revolution of an engine for driving the pump, the displacement of the pump to be larger or smaller than a displacement determined on the basis of a difference between the pump delivery pressure and a load pressure. The displacement controlling circuit system comprises a revolution sensor (12) for detecting rates of revolution of the engine (9), and means (10, 11) for switching a load sensing valve (5) in such a manner that: when the detected rate of revolution of the engine is high, a displacement control member (2) of the variable displacement pump (1) is actuated in a displacement increasing direction; and, when the detected rate of revolution of the engine is low, the displacement control member (2) is actuated in a displacement decreasing direction.