Power transmission

A power transmission comprising:

• a first clutch which is actuated by means of a hydraulically operated first actuator so as to engage a drive element with a first driven element;
• a second clutch which is actuated by means of a hydraulically operated second actuator so as to engage said drive element with a second driven element;
• said first actuator being constructed of a first piston for actuating said first clutch, a first cylinder in which said first piston is slideably disposed, a first working fluid chamber formed upon one side of said first piston between said first piston and said first cylinder and adapted to receive a supply of pressurized hydraulic fluid so as to move said first piston in a direction such that said first clutch is actuated by said first piston, and a first centrifugal hydraulic pressure chamber formed upon the other side of said first piston between said first piston and one side of a first partition fixed upon an end portion of said first cylinder and adapted to receive a supply of fluid the pressure of which is substantially the same as atmospheric pressure;
• and
• said second actuator being constructed of a second piston for actuating said second clutch, a second cylinder, formed within said first partition, in which said second piston is slideably disposed, a second working fluid chamber formed upon one side of said second piston between said second piston and the other side of said first partition and adapted to receive a supply of pressurized hydraulic fluid so as to move said second piston in a direction such that said second clutch is actuated by said second piston, and a second centrifugal hydraulic pressure chamber formed upon the other side of said second piston and adapted to receive a supply of fluid the pressure of which is substantially the same as atmospheric pressure.