Component Parts

The transmission consists of a torque converter (19) with a "lock-up" function (20) and three planetary gear trains (P0-P2), complete with associated brakes, clutches and freewheels

The assembly incorporates a total of four brakes (B0-B3), three clutches (C0-C2) and three freewheels (F0-F2). The brakes and clutches are controlled by shift valves in the hydraulic control system (21). Four forward speeds and back-up (reverse) are available, depending on which brakes and clutches are operated.

The valve for the torque converter lock-up function and the other shift valves in the hydraulic system are controlled by three solenoid valves (S1, S2 and SL). These solenoids are in turn controlled by the Transmission Control Module (TCM). The transmission system pressure solenoid (STH) is also controlled by the TCM.





Solenoid valves S1 and S2 control shifting between 1st, 2nd, 3rd and 4th gears, while solenoid valve SL controls the lock-up function. The diagram illustrates how the shift solenoid valves S1 and S2 are operated to select the various gears.

The torque converter is equipped with a lock-up clutch with a friction lining. A certain degree of slip occurs in the torque converter when lock-up is not engaged. This provides torque amplification proportional to slip. When lock-up is engaged, the engine and transmission are locked together mechanically, eliminating slip and enhancing fuel economy. This eliminates slippage and results in good fuel economy. The introduction of electronic control has enabled the lock-up function to be used in the three highest gears.

NOTE: S1 and S2 are closed in their deactivated position, enabling pressure to be built up in the hydraulic circuit. Pressure is relieved when the valves are activated.