Patent ID: 6145644
Filing Date: 2000-11-14
Classification: B60K,F16D

Abstract:
A hydraulic coupling for use in a driveline apparatus having a sump containing hydraulic fluid to rotatively couple first and second rotary members, the hydraulic coupling comprising:a transfer clutch connected between the first and second rotary members;a piston disposed in a piston chamber and actuatable to engage said transfer clutch and rotatively couple the first and second rotary members;a hydraulic pump for pumping hydraulic fluid from the sump to said piston chamber in response to relative rotation between the first and second rotary members; anda control valve assembly located in a flow path providing fluid communication between said piston chamber and the sump, said control valve assembly having a thermal unload valve for venting fluid from said piston chamber to the sump when the fluid temperature exceeds a predetermined maximum temperature value.