Dual piston actuator

A power transmitting component comprising:

• a friction clutch having a plurality of first clutch plates and a plurality of second clutch plates that are interleaved with the first clutch plates;
• a hydraulic ram coupled to the friction clutch, the hydraulic ram having a ram chamber and a ram piston that is movable in the ram chamber between a first position in which the ram piston is retracted relative to the first and second clutch plates, and a second position in which the ram piston is extended toward the first and second clutch plates to a greater extent than when the ram piston is in the first position;
• and
• an actuator including:
• a housing having a first cylinder and a second cylinder disposed about an axis;
• a first piston received in the first cylinder, the first piston and first cylinder defining a first fluid chamber;
• a second piston received in the second cylinder, the second piston and second cylinder defining a second fluid chamber in fluid communication with the ram chamber;
• and
• a resilient member having a first end coupled for axial translation with the second piston, and a second end coupled for axial translation with the first piston;
• wherein the resilient member is configured to translate the first piston to provide a first volume of fluid at a first pressure to the ram chamber when a pressure in the first chamber is less than a predetermined pressure and the second piston is translated in the second cylinder in a first axial direction, and wherein the resilient member is configured to compress between the first and second pistons to permit relative axial motion between the first and second pistons when the pressure in the first chamber is equal to, or greater than, the predetermined pressure and the second piston is translated in the first axial direction;
• wherein the second piston provides a second volume of fluid at a second pressure to the ram chamber when the pressure in the first chamber is equal to, or greater than, the predetermined pressure and the second piston is translated in the first axial direction, the first volume of fluid being greater than the second volume of fluid, and the first pressure being less than the second pressure.

A power transmitting component comprising:

• a friction clutch having a plurality of first clutch plates and a plurality of second clutch plates that are interleaved with the first clutch plates;
• a hydraulic ram coupled to the friction clutch, the hydraulic ram having a ram chamber and a ram piston that is movable in the ram chamber between a first ram position in which the ram piston is retracted relative to the first and second clutch plates, and a second ram position in which the ram piston is extended toward the first and second clutch plates to a greater extent than when the ram piston is in the first ram position;
• and
• an actuator including:
• a housing having a first cylinder disposed about an axis and a second cylinder coaxial with the first cylinder;
• a first piston received in the first cylinder, the first piston and first cylinder defining a first fluid chamber;
• a second piston received in the second cylinder, the second piston and second cylinder defining a second fluid chamber in fluid communication with the ram chamber;
• a resilient member having a first end coupled for axial translation with the second piston, and a second end coupled for axial translation with the first piston;
• and
• a valve having a fluid passage and a valve body, the fluid passage fluidly coupling the first and second chambers, the valve body being movable relative to the fluid passage between a first valve position wherein the fluid passage is open to permit fluid communication between the first and second chambers, and a second valve position wherein the valve body blocks the valve passage to prevent fluid communication between the first and second chambers;
• wherein the resilient member is configured to axially translate the first piston in a first axial direction when the second piston is translated in the first axial direction and a pressure in the first chamber is less than a predetermined pressure, and the resilient member is configured to compress between the first and second pistons to allow relative axial movement of the first and second pistons between a first relative position and a second relative position when the second piston is translated in the first axial direction and the pressure in the first chamber is equal to, or greater than, the predetermined pressure;
• wherein the first piston is configured to engage the valve body to prevent the valve body from moving to the second valve position when the first and second pistons are in the first relative position, and the valve body is permitted to move to the second valve position when the first and second pistons are in the second relative position.