Abstract: A torque proportioning differential (10) is modified to vary bias ratio in three distinct stages in response to predetermined levels of drive torque. A pair of side gears (26 and 28) carried within a differential housing (12) generate respective thrust forces (44 and 46) that can be opposed by both high-friction gear mounting surfaces (68 and 70) and low-friction gear mounting surfaces (84 and 86). Outer disc springs (72 and 74) transmit a first portion of the thrust forces (44 and 46) to the low-friction gear mounting surfaces (84 and 86). Inner disc springs (64 and 66) transmit together with the outer disc springs (72 and 74) a second portion of the thrust forces (44 and 46) up to a second magnitude. Either the inner disc springs (64 and 66) or the outer disc springs (72 and 74) transmit the remaining portion of the thrust forces ( 44 and 46) above the second magnitude.

Abstract: Frictional effects at different gear mounting surfaces within a differential are varied to control bias ratio. The gearing arrangement includes side gears respectively coupled to axle ends and element gears which transfer and divide torque between the side gears. Coefficients of friction at end faces of the element gears are varied between different element gears to control overall bias ratio while minimizing the effect of changes in overall bias ratio on an inherent bias ratio imbalance between opposite directions of differentiation. Helical gear portions are formed at the ends of the element gears to better balance thrust forces acting on different element gears.

Abstract: A gear differential includes planetary gear sets made up of two side gears (26, 28) mounted for rotation about a common axis (24) and pairs of element gears (36, 38) mounted for rotation about respective parallel axes (48, 50) that are both offset and inclined through acute shaft angles (L.sub.1, L.sub.2) with respect to the common side gear axis (24). The two element gears (36, 38) have first gear portions (52, 54) that mesh with respective side gears (26, 28) and second gear portions (56, 58) that mesh with each other. The side gears (26, 28) have respective helix angles (A.sub.1, A.sub.2) that are substantially equal in absolute magnitude but opposite in hand. However, lead angles of the side gears (26, 28), as the complements of their respective helix angles (A.sub.1, A.sub.2), are larger than the shaft angles to provide opposite directions of relative rotation between the side gears.

Abstract: A torque proportioning differential (10, 60, or 120) is modified to exhibit a bias ratio that varies with torque transmitted by the differential. Thrust forces (34 and 36, 88 and 90, or 144 and 146) generated within the differential are opposed by at least one pair of surfaces (38 and 40, 96, 98 and 104, 106, or 152, 154 and 156, 158) having different frictional characteristics. One of the surfaces (38, 96 and 98, or 152 and 154) opposes a portion of the thrust forces, and the other surface (40, 104 and 106, or 156 and 158) opposes a remaining portion of the thrust forces. A control member (54, 100 and 102, or 152) responsive to the transmitted torque limits the respective portions of the thrust forces opposed by each of the two surfaces.