Automatic differential control apparatus

Abstract

A multi-position clutch is disclosed for use with a between-front-and-rear axle differential of a multiple drive axle vehicle, having an engaged position to eliminate differential action in transmitting power between front and rear axle, normal intermediate overrun clutch position to prevent front wheel spinout faster than the rear, and a completely disengaged position for elimination of overrunning clutch lockup and excessive front driveline torque loads during moderate to panic brake applications. The clutch includes a linear fluid motor responsive to front-axle braking of the vehicle for applying fluid pressure in a first direction to the fluid motor to transfer the clutch to the disengaged position at a predetermined vehicle deceleration to prevent excessive drivetrain torque buildup between the front wheels and the rear brakes. Means are also provided for selectively applying fluid pressure in a second direction to move the fluid motor opposite the first direction, thereby moving the clutch into the engaged position. This provides positive differential lockup to resolve the rare case of rear-wheel-only spinout. Spring means return the fluid motor to a normal intermediate position, repositioning the clutch to the overrun position when no fluid pressure is applied to the fluid motor. This free differential drive position positively prevents the front wheels from spinning out faster than the rear during hill climbing or towing loads or any other condition of operation. It consequently allows the free differential drive to provide maximum vehicle performance for the majority of high mobility requirements.

Dependencies are inferred from the claim text.