Chevrolet TrailBlazer, Service Manual, Page: 405 / 677

impeller to turn much faster than the turbine. This difference in speed may be compared to
the difference in speed between the smaller and larger gears in any gear train. The result
is that engine power output is higher, and engine torque is multiplied.
As the speed of the turbine increases, the fluid spins faster and faster in the direction of
engine rotation. As a result, the ability of the stator to redirect the fluid flow is reduced.
Under cruising conditions, the stator is eventually forced to rotate on its one-way clutch in
the direction of engine rotation. Under these conditions, the torque converter begins to
behave almost like a solid shaft, with the impeller and turbine speeds being almost equal.
Lock-up Converter
The lock-up converter contains the same components as a conventional converter but also
includes a clutch assembly that, when applied connects the engine directly to the
transmission. The result is no slippage, and therefore virtually no power loss. An electronic
control system is used to determine when to apply the converter clutch.
Planetary Gearbox
The ability of the torque converter to multiply engine torque is limited. Also, the unit tends
to be more efficient when the turbine is rotating at relatively high speeds. Therefore, a
planetary gearbox is used to carry the power output of the turbine to the driveshaft.
Planetary gears