Automatic Transmission/Transaxle: Description and Operation

DESCRIPTION

Cross-sectional View Of Transaxle:

This automatic overdrive transaxle, is a fully automatic transaxle with four forward speeds and one reverse, in addition to neutral and park.

CONSTRUCTION
The transaxle has two planetary gear sets and a combination planetary/differential gear set. Four multiple plate clutches, two band assemblies, and two one-way clutches. A lock-up torque converter is coupled to the engine crankshaft and transmits engine power to the gear train by means of a drive link assembly (chain) that connects the drive and driven sprockets.

OPERATION

Clutch And Band Application Chart:

Converter clutch application is controlled through an electronic control integrated in the on-board Electronic Engine Control IV (EEC IV) or Electronic Engine Control V (EEC V) system. These controls, along with the hydraulic controls in the valve body, operate a piston plate clutch in the torque converter to provide improved fuel economy by eliminating converter slip when applied.

Downshifts
Under certain conditions the transaxle will downshift automatically to a lower gear range without moving the shift selector lever. There are three different types of downshift categories:

Coastdown - The coastdown downshift occurs when vehicle is coasting down to a stop.

Torque demand - The torque demand downshift occurs during part throttle acceleration when the demand for torque is greater than the engine can provide at that gear ratio. The transaxle will disengage the converter clutch to provide added acceleration, if applied.

Kickdown - The kickdown downshift occurs when the accelerator pedal is depressed fully to the floor. A forced downshift into second gear is possible below 55 mph. Below approximately 25 mph a forced kickdown to first gear will occur. All shift speed specifications will vary due to tire size and engine calibration requirements.