Abstract: A clutch assembly, including: a secondary piston assembly; a primary piston including a portion located radially outward of the secondary piston assembly; a first chamber at least partially formed by a first side of the primary piston; a second chamber at least partially formed by the secondary piston assembly and a second side of the primary piston; and a check valve connecting the first and second chambers. For a first force applied by fluid in the first chamber: the primary piston remains axially stationary; the fluid flows from the first chamber into the second chamber; and the secondary piston assembly displaces in a first axial direction to contact a clutch pack. For an increase of the first force to a second force: fluid flow between the first and second chambers is blocked by the check valve; and the primary piston and the secondary piston assembly displace in the first axial direction to close the clutch pack.

Abstract: A vehicle drive device has an engine, a transmission, a clutch device and a clutch operating mechanism which operates the clutch device to drivingly connect the engine to the transmission. The clutch operating mechanism has a clutch drum secured to the outer circumferential surface of an input shaft of the transmission and holding a second clutch section which is engageable with a first clutch section held on an input member of the clutch device to which a driving power of the engine is transmitted. The clutch drum has a drum chamber, a fixed plate closing an opening of the drum chamber, a piston surrounded by the clutch drum and partitioning the drum chamber into a hydraulic chamber and a spring chamber, and an urging element provided inside the spring chamber to be surrounded by the clutch drum and urging the piston.

Abstract: A hydraulic servo for a brake in an automatic transmission has a piston secured against rotation without provision of a protrusion on the piston engaging the transmission casing. The piston of the hydraulic servo has an inner cylindrical surface configured to grasp, along their lengths, return springs compressed between the piston and a return plate to which the return springs are fixed. The return plate is bolted to a bulkhead portion of the transmission case and, thus, the piston member is fixed to the bulkhead portion and thereby prevented from rotating.