Abstract: A system for controlling the torque to be transmitted by a fluid-operated friction coupling (clutch or brake) in an automatic speed changer comprises a processor which receives readings of the rotary speeds of an input member and an output member to be interengaged by that coupling and calculates the instantaneous relative angular acceleration .alpha.=-d.vertline..DELTA.n.vertline./dt from these data, the value .alpha. being supplied to a comparator. A computer receiving the same readings determines the optimum acceleration and feeds the result to the comparator whose output actuates a governor controlling the fluid pressure supplied to the coupling.

Abstract: An automotive transmission comprises a plurality of cascaded planetary-gear stages consisting each of a sun gear, a planet carrier and a ring gear. The stages, or some of them, constitute modular units which may be added or eliminated to vary the number of available speed ratios. With four stages and eight selectively operable coupling elements, i.e., four clutches and four brakes, eight forward speeds and six reverse speeds may be realized. The sun gears of three stages are fixed to a common intermediary shaft, connectable to an input shaft by one of the clutches, while the corresponding ring gears are individually immobilizable by respective brakes. Two of the three components of the fourth stage, namely the carrier and the ring gear, are cross-connected with the ring gear and the carrier of the third stage and, like the sun gear of this fourth stage, may be individually linked with the input shaft via other intermediate shafts and associated clutches.