Planetary gearbox clutch actuation system with lube boost

摘要

A hydraulic clutch actuation system 11, for a planetary gearbox in a powertrain, comprises a lubrication circuit 15 having lube valve 46 which has a lube position in which a lube line 57 is provided with line pressure from a pump 43 and a lube boost position in which a lube boost line 58 and the lube line 57 are provided with the line pressure. The lube boost line 58 is connected to a lubrication area of clutches 16-20 in dependence upon which gear is selected. Clutches 16-20 are operated by pistons in cylinders which are connected via valves to the pump 43 that supplies the cylinders with pressurized fluid. In another embodiment a multiplex valve 25 has a first position in which an input port is connected to a first port in order to engage first or second gear and a second position in which the input port is connected to second port in order to engage second gear.