AUTOMATIC CLUTCH FOR FOUR-WHEEL DRIVE VEHICLES

摘要

AUTOMATIC CLUTCH FOR FOUR-WHEEL DRIVE VEHICLES This invention relates to an automatic four-wheel drive clutch characterized by a sliding gear subassembly having a toothed ring facing outwardly, a cam ring with concave toothed cams on its inwardly-facing surface and springs between these two rings normally biasing them apart, all elements of the subassembly being mounted for both conjoint rotation with the axle and axial slidable movement therealong between a retracted inoperative position and an extended engaged one wherein its toothed ring lies in meshed driving engagement with an opposed ring of teeth carried by a driven element that turns with the front steerable wheel; a first biasing means engaging the sliding gear subassembly and normally urging same into disengaged position; a rotatable bearing subassembly including inner and outer sleeve bearings slidable over opposed cylindrical surfaces rotatable with the axle and wheel respectively and a set of toothed rollers mounted for rotation in equiangularly-spaced relation around an annular gap left between the opposed surfaces of the two bearings; a thrust plate carrying a ring of teeth arranged in opposed relation to the toothed cams of the sliding gear subassembly mounted for limited axial and free rotational movement, the teeth of this thrust plate defining a circular track for the rollers to run around in meshed relation while traveling in and out along the cams; braking means including a friction member mounted for limited axial movement behind the thrust plate in annular frictional engagement with the face thereof opposite its ring of teeth; and second biasing means interposed between an abutment on the wheel spindle and the braking means normally urging its friction member against the thrust plate, the latter biasing means being operative with the axle turning to prevent rotation of the thrust plate thereby forcing the rollers to climb to one end or the other of the cams thereby extending the sliding gear subassembly into engaged position, the second biasing means also being operative with the axle turning and the cams at one end or the other of their cam surfaces to permit the elements so interengaged to turn as a unit with the wheel while sliding over the friction element; and the second biasing element being further operative with the axle disengaged to cooperate with the first biasing means to hold the thrust plate stationary while the wheel is rotated in the direction opposite that in which the axle last turned while engaged thus turning the bearing assembly and driving the rollers into the bottom of the cams where the first biasing means becomes effective to retract and disengage the sliding gear subassembly. The invention also encompasses manual override mechanisms operative to releasably latch the clutch into either engaged or disengaged condition regardless of whether the axle is engaged or not.