Selectable valve assembly for a vehicle transmission

A hydraulic valve assembly for controlling a clutch in a vehicle transmission, comprising:

• a housing with a first port for connection to a source of pressurized hydraulic fluid;
• a displaceable sealing piston disposed within the housing;
• a valve spring for displacing the sealing piston;
• a snap-spring having first and second equilibrium positions;
• an overstroke spring, wherein:
• in the first equilibrium position, the snap spring holds the sealing piston in an open position to enable fluid flow through the valve;
• in the second equilibrium position, the snap spring is displaced away from the sealing piston and the valve spring holds the sealing piston in a closed position to block fluid flow through the valve;
• and,
• moving from the first equilibrium position to the second equilibrium position comprises displacing the overstroke spring;
• and,
• an overstroke piston, wherein the overstroke piston is displaceable to displace the overstroke spring.

A hydraulic valve assembly for a vehicle transmission comprising:

• a housing;
• a sealing piston disposed within the housing and displaceable to open and close the valve;
• a snap-spring having first and second equilibrium positions;
• a valve spring;
• and,
• a displaceable overstroke spring;
• wherein
• in the first equilibrium position the snap-spring displaces the sealing piston to hold the valve in an open position;
• in the second equilibrium position the valve spring displaces the sealing piston to hold the valve in a closed position;
• and,
• transitioning from the first equilibrium position to the second equilibrium position comprises displacing the overstroke spring.