Hydraulic actuation of clutch in automatic gearbox in motor vehicle has valve to decouple clutch in emergency conditions

摘要

The hydraulic actuator (10) has two hydraulic regulator cylinders (46,68,70), and two proportional hydraulic valves (44,62,64,66). A command valve (54) supplies hydraulic fluid to one of these valves as a function of hydraulic pressure from one of the valves (44). A valve holds the clutch disengaged under emergency conditions, independently of losses from valves.