Hydraulically operable transmission having controlled pressure rise in clutch

摘要

A hydraulically operable transmission comprises a hydraulic separating clutch (501), a change speed control valve (10), change speed actuators (101, 102, 103) controllable by the control valve, a pilot oil line (11) for varying pressure states in response to operation of the actuators, an oil supply line (8) extending to the hydraulic clutch, a clutch control valve (9) operable with a pilot pressure applied from the pilot oil line to close the oil supply line, and a pressure buildup device (200) mounted on the oil supply line. The pressure buildup device includes an oil chamber for producing predetermined pressure increase characteristics with a pilot pressure applied from the oil supply line and a spring load, a drain line (34) extending from the oil chamber, and a drain control valve (35) mounted on the drain line for opening and closing the drain line in response to the pilot pressure applied from the pilot oil line.