Input shafttransfers power from the torque
converter to internal drive members and
Oil pumpproduces pressure to operate
hydraulic components in the transmission.
Valve bodyoperated by shift lever and
sensors; controls oil flow to pistons and servos.
Pistons and servosactuates the bands and
Bands and clutchesapplies clamping or
driving pressure on different parts of gearsets to
Planetary gearsprovides different gear ratios
and reverse gear.
Output shafttransfers engine torque from the
gearsets to the drive shaft and rear wheels.
The torque converter is a fluid clutch that performs
the same basic function as a manual transmission dry
friction clutch (fig. 4-24). It provides a means of
uncoupling the engine for stopping the vehicle in gear.
It also provides a means of coupling the engine for
A torque converter has four basic parts:
Outer housingnormally made of two pieces of
steel welded together in a doughnut shape,
housing the impeller, stator, and turbine. The
housing is filled with transmission fluid.
Impellerdriving member that produces oil
movement inside the converter whenever the
engine is running. The impeller is also called the
Turbinea driven fan splined to the input shaft
of the automatic transmission. Placed in front of
Figure 4-24.Torque converter, partial cutaway view.