Hydraulic apparatus

A hydraulic apparatus for changing the flow rate by displacing a flow rate changing member of a variable displacement hydraulic pump accommodated in a casing, comprising, in combination:

• an actuator, a first sliding member slidably received in a first cylinder chamber provided in said casing and movable in one direction to urge said flow rate changing member toward a direction where the flow rate of said hydraulic pump is decreased, a second sliding member slidably received in a second cylinder chamber provided in said casing and movable in said one direction to urge the flow rate changing member toward a direction where the flow rate of said hydraulic pump is decreased, a resilient member accommodated in said casing to resiliently urge said flow rate changing member against a resultant force of said first and second sliding member toward a direction where the flow rate of said hydraulic pump is increased, said resilient member being the only means for urging said first and second sliding members in a direction opposite to said one direction, a first fluid conduit having one end connected with an outlet port of said hydraulic pump and the other end thereof connected with a rear port of said actuator, a second fluid conduit having one end connected with a fore port of said actuator and the other end connected with a port of a pressure compensated flow control valve means for permitting pressure oil passing therethrough to be maintained constant in volume even with variations in pressure of the fluid, a third fluid conduit having one end connected with another port of said flow control valve means and the other end thereof connected with an inlet port of the hydraulic pump, a fourth fluid conduit having one end connected with said second fluid conduit and the other end connected with said first cylinder chamber, and a fifth fluid conduit having one end connected with said first fluid conduit and the other end connected with said second cylinder chamber.