General System Description

Fig. 4 Cross-sectional View Of Transmission.:

The 4L60-E, Fig. 4, is a fully automatic transmission consisting of a 3-element hydraulic torque converter with the addition of a converter clutch. Also two planetary gearsets, five multiple-disc type clutches, two roller or one-way clutches and a band are used which provide the friction elements to produce four forward speeds, the last of which is Overdrive.
The torque converter couples the engine power to the gearsets and hydraulically provides additional torque multiplication when required. Also, through the converter clutch, the converter drive and driven members operate as one unit when applied, providing mechanical drive from the engine through the transmission.
The gear ratio changes are fully automatic in relation to the vehicle speed and engine torque. Vehicle speed and engine torque are directed to the transmission providing the proper gear ratio for maximum efficiency and performance at all throttle openings.
A Powertrain Control Module (PCM) manages engine and transmission functions as a single system. The PCM retards engine spark for an instant during each gear shift which reduces engine torque as the gear is engaged. After the shift is completed, spark is advanced and torque is brought to normal operating levels. Shifting is accomplished by sensor-driven servos located within the transmission valve body.