PURPOSE: To make improvements in the responsiveness of a retard (deceleration) by controlling a level of pressure to be fed out of a sub-fluid pressure source by means of a regulator when pressure at hydraulic retarder is in the specified level.
CONSTITUTION: According to a request retardation level, a solenoid valve 108 makes a specified pressure act on a land part 104 of a regulating valve 66, and with movements of a spool 102, an output passage 38 of a converter 18 is interconnected to a passage 28, feeding a hydraulic retarder 10 with a sub- pressurized fluid source. Pressure in this passage 28 is guided into a chamber 114, of the regulating valve 66, regulating a flow from the passage 38 to the passage 28. At this point of time, a solenoid valve 92 is turned to OFF, whereby any supply or exhaust to or from the hydraulic retarder 10 from an accumulator 14 via check valves 84 and 88 is not carried out, so inlet pressure in this retarder 10 is secured, and thereby a flow of fluid into the retarder is controlled by the solenoid valve 108 and the regulating valve 66. Thus responsiveness for retardation is improved, and further any leakage loss in a transmission is thus reducible.
DENISU MAIKERU KUUKU
JIYON RICHIYAADO BITONAA
JIEEMUZU TOOMASU KUREIGU
