Abstract: A power transfer unit for a motive device comprises an outer housing, an inner housing, and a torque transferring clutch. A piston housing is located between the outer housing and the torque transferring clutch. A piston is located in the piston housing. The piston is configured to provide actuation forces to the torque transferring clutch. And, when the torque transferring clutch receives the actuation forces, the torque transferring clutch causes the inner housing to rotate.

Abstract: A power transfer unit (PTU) for a motive device includes an outer housing and a torque transferring clutch. The PTU also includes a piston housing located between the outer housing and the torque transferring clutch, and a piston in the piston housing. The piston is arranged to provide actuation forces to the torque transferring clutch, and to restrict reaction forces back to the piston housing.

Abstract: A marine transmission provides a cylindrical spool valve that is disposed within the gear case of the transmission and has a movable portion that is axially movable in a vertical direction to select forward, neutral, and reverse gear positions of the transmission. A piston assembly provides a primary piston and two auxiliary pistons which cooperate with each other to provide appropriate hydraulic forces which move a dog clutch into engagement with forward or reverse gears or toward a location in non-engagement with neither the forward nor reverse gears. The spool valve is generally cylindrical and disposed within a narrow column portion of the gear case of a marine propulsion system.