The THM 4T60-E is a fully automatic 4 speed front wheel drive transaxle. It consists primarily of a four element torque converter, two planetary gear sets, various multi-disc clutches, a
differential assembly, and a control valve body.
The four element torque converter contains a pump, a turbine, a pressure plate splined to the turbine, and a stator assembly. The torque converter acts as a fluid coupling to smoothly transmit power from the engine to the transaxle. It also hydraulically provides additional torque multiplication when required. The pressure plate, when applied, provides a mechanical "direct
drive" coupling of the engine to the transaxle.
The two planetary gear sets provide the four forward gear ratios and reverse. Changing of the gear ratios is fully automatic and is accomplished through the use of various electronic engine
sensors that provide input signals to the Powertrain Control Module (PCM). The PCM interprets these signals to control current to the various shift solenoids, converter clutch solenoids, or switches inside the transaxle, as shown in Figure 2. By using electronics, the PCM controls shift points and torque converter apply and release, to provide proper gear ranges for maximum fuel economy and vehicle performance.
Four multiple-disc clutches, two sprags, a roller clutch, and three bands provide the friction elements required to obtain the various gear ratios with the planetary gear sets. A hydraulic system which consists of the control valve body, pressurized by a vane type pump, provides the working pressure needed to operate the friction elements and automatic controls.
Several electronic switches, solenoids and sensors, as shown in Figure 2, are working in conjunction with the vehicles PCM or Electronic Control Module (ECM), control various shift points and the apply and release of the converter clutch.