AUTOMATIC TRANSMISSION – GM 5L40-E DESCRIPTION AND OPERATION The gearset has three elements torque inputs, reaction components and torque outputs. The three possible torque inputs are: l Planetary carrier l Front input sun gear l Rear input sun gear. The three possible reaction components are: l Planetary carrier l Front ring gear l Front input sun gear. One torque output: l Rear ring gear. The following table shows the different combinations of input components, reaction components and output components required to achieve the five forward gears and the one reverse gear ratio. Gear Ratios Gear Input Reaction Output Ratio 1st Rear input sun gear Planetary carrier Rear ring gear 2nd Rear input sun gear Front ring gear Rear ring gear 3rd Rear input sun gear Front input sun gear Rear ring gear 4th Rear input sun gear and planetary carrier None Rear ring gear 5th Planetary carrier Front input sun gear Rear ring gear 0.75 Reverse Front input sun gear Planetary carrier Rear ring gear 3.03
AUTOMATIC TRANSMISSION – GM LE DESCRIPTION AND OPERATION Power Flows Operation of the transmission is controlled by the EAT ECU which electrically activates various solenoids to control the transmission gear selection. The sequence of solenoid activation is based on programmed information in the ECU memory and physical transmission operating conditions such as vehicle speed, engine load, throttle position and selector lever position.