Abstract: In an arrangement for automatically changing gear in an epicyclic change-speed gearbox from a previous gear, in which a first frictional connection (clutch or brake) is engaged, into another gear, in which a second frictional connection is engaged, the working pressure for engaging the first frictional connection is switched off when the working pressure for engaging the second frictional connection reaches a significant pressure value. The pressure value is determined by comparison with a reference parameter which depends on the load torque.

Abstract: There is proposed a practical approach to a shift, in an automatic transmission, in which a release element is released and an apply element is engaged. The release element is released or vented at an appropriate timing after development of torque by the apply element but before initiation of inertia phase. Specifically, the release element is released when transmission output torque (To) reaches a value (Toh) calculated out of gear ratio after shift (grmin), transmission input (or turbine) torque (Tt) and transmission input (turbine) acceleration (NTd). If desired, without relying on measurement of output torque (To), the release element may be released when transmission output acceleration (No), namely, vehicle acceleration, reaches a value which may be fixed or accelerator position dependent.

Abstract: Multi-mode friction clutch having a plurality of interleaved clutch plates operable for establishing gear ratios in planetary and countershaft type automatic transmissions and operative to provide smooth and self-synchronized shifting without the use of one-way roller or sprag clutches. Gear thrust forces from associated helical gearing and opposing hydraulic pressure forces are used to regulate the hydraulic pressure of a piston chamber by shifting an annular control sleeve which controls fluid exhaust from the chamber to maintain a direct relationship between the torque capacity of the clutch and the variable torque it actually carries. Consequently, the clutch is automatically released when the transmitted torque diminishes to zero or reverses. The clutch is applied in a normal lock mode for predetermined gear ratios, set in one-way mode for shifting and totally released when the shift is completed.

Abstract: A drive system for driving an endless chain of a mineral mining installation employs one or more chain wheels each driven by an electric motor and gearing including planetary gearing. The planetary gearing has a ring gear which can be held stationary to permit drive to be transmitted. The ring gear is coupled through a clutch, reduction gearing and a braking device to another load-balancing electric motor. Load sensors in the reduction gearing disengage the clutch in the event of overloading. The ring gear is automatically held stationary by the braking device when the load-balancing motor is inoperative. When the motor is switched on the braking device is released to permit the motor to rotate the ring gear in one direction or the other at controlled speed to vary the transmission ratio and effect load balancing.