Importance

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Abstract

A transfer case having a mechanically parallel overrunning clutch and centrifugal, speed proportional clutch provides improved handling characteristics especially in off-throttle driving conditions. The transfer case includes a one-way or overrunning clutch which provides drive from the rear driveline to the front driveline to rotate the front driveline and wheels at least as fast as the rear driveline and wheels. For example, the one-way clutch will be engaged when the rear drive wheels lose traction and attempt to overspeed the front drive wheels. The clutch overruns, however, if the front driveline and wheels are urged to overrun the rear driveline. The mechanically parallel speed responsive, i.e., centrifugal, clutch provides speed proportional engagement or coupling between the two drivelines and is particularly effective to reduce speed differences therebetween as its clutching and torque transfer effects are in direct proportion to the speed difference between the two drivelines. The preferred embodiment transfer case assembly is a single speed device incorporating the overrunning and centrifugal clutches. A first alternate embodiment transfer case assembly includes not only the overrunning and centrifugal clutches but also a speed reducing planetary gear assembly which provides a reduced speed drive range in addition to direct drive.

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First Claim