A/T System Description - General Operation (9-Speed A/T: 4WD)
General Operation
The automatic transmission has four planetary gear sets and six clutches and it is possible to change the gears (forward of 9 steps, reverse of 1 step) by them. To change the gears, the solenoid valves and the pressure regulators in the hydraulic control unit switch hydraulic passages and are controlled by the transmission control module (TCM).
Torque Converter
The torque converter is connected to the drive plate. It consists of a pump wheel, turbine wheel, stator and a torsional damper, which uses ATF to transmit engine power to the input shaft.
Lock-Up Mechanism
The lock-up causes the input shaft to rotate at the same speed as the engine crankshaft by engaging the torque converter cover with the turbine by the torque converter lock-up clutch. Together with the hydraulic control, the TCM optimizes the timing and degree of lock-up by controlling the solenoid.
Gear Selection
The shift position/mode has five positions; P: PARK, R: REVERSE, N: NEUTRAL, D: DRIVE (1st through 9th gear ranges with automatic shift mode and D-paddle shift mode), and S: SPORT DRIVE (1st through 8th gear ranges with automatic shift mode and 1st through 9th gear ranges with sequential shift mode).
Shift Indicator and M Indicator
When you operate the paddle shifter, the shift indicator in the gauge control module displays the selected gear. The shift indicator also displays the selected gear in the D-paddle shift mode and the sequential shift mode.
Transfer Assembly
The transfer assembly consists of the transfer hypoid drive gear/shaft assembly, the transfer output shaft (hypoid gear), and the companion flange. The transfer assembly is on the rear side of the transmission, beside the differential. The transfer drive gear on the differential drives the transfer output shaft in the transmission. The transfer output shaft in the transmission is connected to the transfer hypoid drive gear/shaft assembly by splines. Power is transmitted from the transfer drive gear on the differential to the rear differential via the transfer assembly and the propeller shaft.