Automatic Transmission/Transaxle: Description and Operation

Fig 2 Cut-away View Of 4L60-E Transaxle:

The 4L60-E Fig. 2 is an electronically controlled transmission consisting of a 3-element hydraulic torque converter with the addition of a converter clutch. A Power 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.

Also two planetary gear sets, 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, through oil, couples the engine power to the gear sets 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 hydraulic system pressurized by a variable capacity vane-type pump, provides the operating pressure required for the operation of the friction elements and automatic controls.