To change the capacity of a hydraulic tank according to the surplus flow rate or insufficient flow rate used of a fluid pressure actuator.
A hydraulic package is constituted such that a driving motor 2 and a hydraulic tank 10 are disposed respectively on the left and right of a hydraulic pump 1 incorporated with a circuit block 40. A first and second passage 41, 43 of the circuit block 40 are made to be communicated with a hydraulic actuator with area difference of the received pressure, and the passage 42 is communicated with a bellows 12 provided in a tank cover 11 elastically, so that the bellows 12 is energized by a spring 14 to the contracted direction. The tank capacity is changed by the bellows 12 which is extended and contracted automatically according to the surplus flow rate or insufficient flow rate produced in the pipe line to the hydraulic actuator caused by the operation of the hydraulic pump 1.
NAKAO HIROTOSHI
KIHARA KAZUYUKI
