Patent ID: 8037988

Claim:
A control system for selectively actuating a dual area apply piston having first and second piston areas each selectively biased by hydraulic pressure within a respective first and second fill cavities, the dual area apply piston being operable to engage a torque-transmitting mechanism, the control system comprising: a line pressure source of hydraulic pressure; a pressure regulator valve in communication with said line pressure source; wherein said pressure regulator valve has a spring set position, a trim position, and a pressure set position; wherein said pressure regulator valve is operable to selectively and variably communicate hydraulic pressure from said line pressure source to the first fill cavity when said pressure regulator valve is in one of said trim position and said pressure set position; a dual area activation valve in communication with said pressure regulator valve; wherein said dual area activation valve has a spring set position and a pressure set position; and wherein said dual area activation valve is operable to selectively communicate hydraulic pressure from said line pressure source to the second fill cavity via said pressure regulator valve when said pressure regulator valve is in said pressure set position and said dual area activation valve is in said pressure set position.