Torque Converter

Torque Converter





The torque converter transmits and multiplies torque. The torque converter is a four-element device:
^ impeller assembly
^ turbine assembly
^ reactor assembly
^ clutch and damper assembly

The standard torque converter components operate as follows:
^ Rotation of the converter housing and impeller set the fluid in motion.
^ The turbine reacts to the fluid motion from the impeller, transferring rotation to the geartrain through the input shaft.
^ The reactor redirects fluid going back into the impeller, allowing for torque multiplication.
^ The clutch and damper assembly dampens powertrain torsional vibration and provides a direct mechanical connection for improved efficiency.
^ Power is transmitted from the torque converter to the planetary gearsets and other components through the input shaft.

Geartrain
Power is transmitted from the torque converter to the Ravigneaux geartrain components through the input shaft and forward clutch cylinder.
^ The geartrain contains a Ravigneaux planetary set connected by dual pinion gears.





^ By holding or driving certain components of the gearset, four forward ratios and one reverse ratio are obtained and transmitted to the output shaft. The ratios are as shown.
^ Components of the geartrain can be held by bands or clutches and driven by clutches only.

The 4R70W uses:
^ two bands.
^ two one-way clutches (one roller, one mechanical diode).
^ four friction clutches.

Planetary Gearset
The planetary gearset in the transmission is a Ravigneaux-type set consisting of the following components:
^ forward clutch sun gear
^ reverse clutch sun gear
^ a pinion carrier
^ long and short pinions
^ output ring gear

Components are held or driven to produce forward and reverse gear ratios.

Input Shaft
The forward clutch cylinder and shaft transfers speed and torque from the converter turbine to the geartrain. This shaft is splined to the turbine on one end and to the forward clutch sun gear and stub shaft on the other end.

Stub Shaft
The stub shaft transfers power from the input shaft to the planet carrier (through the direct clutch) during third and fourth gear operation.

Output Shaft
The output shaft provides torque to the driveshaft and rear axle assembly. It is driven by the ring gear of the planetary gearset.