CVT System Description - General Operation
The continuously variable transmission (CVT) is an electronically controlled automatic transmission with drive and driven pulleys, steel
belt, and new transmission fluid (HCF-2). The CVT provides non-stage speeds forward and non-stage speeds reverse. The entire unit
is positioned in line with the engine.
The torque converter consists of a pump, a turbine, and a stator assembly in a single unit. The torque converter cover is connected to
the engine crankshaft and turns as the engine turns. Around the outside of the torque converter is a ring gear which meshes with the
starter drive gear when the engine is being started. The entire torque converter assembly serves as a flywheel, transmitting power to
the transmission input shaft. The transmission has four parallel shafts: the input shaft, the drive pulley shaft, the driven pulley shaft,
and the final drive shaft. The input shaft is connected to the torque converter turbine, and integrates the forward clutch on the drive
pulley shaft end. The drive pulley shaft and the driven pulley shaft consist of movable and fixed face pulleys. Both pulleys are linked
by the steel belt. The input shaft includes the forward clutch. The drive pulley shaft includes the drive pulley. The input shaft is
connected with the drive pulley shaft by the forward clutch hub/sun gear, and by the ring gear, the planetary pinion gears, and the sun
gear. The planetary carrier is positioned between the ring gear and the sun gear, and engaged with the planetary pinion gears. The
driven pulley shaft includes the driven pulley (with the park gear). The secondary drive gear is splined to the driven pulley shaft. The
final drive shaft is positioned between the secondary drive gear and the final driven gear. The final drive shaft integrates the secondary
driven gear and the final drive gear which serves to change the rotational direction of the drive and driven pulley shafts, because the
drive pulley shaft and the driven pulley shaft rotate the same direction. When the input shaft is joined with the drive pulley shaft by
engaging the forward clutch or the reverse brake, power is transmitted through the input shaft, the drive pulley shaft, the driven pulley
shaft, to the final drive shaft provide drive.
The electronic control system consists of the transmission control module (TCM), sensors, and solenoid valves. Shifting and lock-up
are electronically controlled for comfortable driving under all conditions. The TCM is located in the engine compartment.
The hydraulic control system is controlled by the TCM, the transmission fluid pump, and the valves and the solenoid valves in the
valve body. The transmission fluid pump is driven by the engine turns. The transmission fluid pump drive sprocket is connected to the
stator shaft, turns as the engine turns, and drives the transmission fluid pump driven sprocket by the transmission fluid pump drive
chain. The transmission fluid pump supplies hydraulic pressure to the hydraulic circuit. Fluid from the transmission fluid pump passes
to the various control valves, the drive/driven pulleys, the forward clutch, and the reverse brake.
To shift pulley ratio, the TCM controls shift solenoid valve B, the CVT drive pulley pressure control solenoid valve, the CVT driven
pulley pressure control solenoid valve, the CVT clutch pressure control solenoid valve, and the CVT lock-up clutch control solenoid
valve while receiving input signals from various sensors and switches located throughout the vehicle. The TCM actuates the CVT
drive pulley pressure control solenoid valve and the CVT driven pulley pressure control solenoid valve to change drive and driven
pulley pressures. The drive pulley pressure is applied to the drive pulley, and the driven pulley pressure is applied to the driven pulley,
and pulley ratio is changed to their effective ratio.
The lock-up mechanism of the torque converter clutch operates in D position/mode, S position/mode, and L position/mode, at
transmission fluid temperature exceeding 68 °F (20 °C). The pressurized fluid is drained from the back of the torque converter through
d passage, causing the torque converter clutch piston to be held against the transmission fluid pump. As this takes place, the
input shaft and the drive pulley shaft rotate as the same as the engine crankshaft. Together with hydraulic control, the TCM optimizes
the timing of the lock-up mechanism. When shift solenoid valve B is turned ON by the TCM, shift solenoid valve B pressure switches
lock-up ON and OFF. The CVT lock-up clutch control solenoid valve controls the volume of lock-up.
The shift lever has following position/mode;
P: PARK Front wheels locked; the parking brake pawl engages with the park gear on the driven pulley.
The forward clutch disengages.
R: REVERSE The reverse brake engages, and it locks with the planetary carrier to the transmission housing.
N: NEUTRAL The forward clutch disengages.
D: DRIVE Transmission automatically adjusts to keep the engine at the best rpm for driving under all
The lock-up mechanism operates in this position/mode.
The WOT Step Shift Mode* operates in this position/mode.
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