1. Fluid Coupling Torque Multiplication

2. Torque converter purposes
Allows vehicle to stop in gear
Creates connection between engine and transmission
When using locking converter a 1:1 link can be established
Multiplies torque at low RPMs

3. Basic components Turbine Impeller Stator with one-way clutch
Pressure plate if lock-up

4. Operation Impeller Turbine Part of housing bolted to flexplate
Pumps fluid by centrifugal force
Throws fluid out to contact turbine vanes
Turbine
Locked to input shaft
Acted on by force of fluid
Spins faster based on fluid force
Can only obtain 90% of impeller speed unless lockup style

5. Operation of stator
Fluid flow can be re-directed to “help” impeller at lower speeds increasing torque of engine
Fluid re-directing is performed by stator
After torque multiplication is not desired stator overruns
Defective one way clutch can cause lack of power at low or high rpm

6. Stall speed
Stall speed is the point when engine rpm is limited by fluid pressure on turbine
Controlled by vane design and stator
Too low stall speed can indicate stator problems
Too high can indicate slipping trans.

7. Torque converter facts
Fluid for coupling is supplied by trans. pump through shaft
Most of the heat is created in converter
Usually just before cooler
Not a serviceable unit
Can hold 10+ quarts of oil
Converter housing often drives trans. oil pump
Watch for loose bolts

8. Converter lock-up Performed by mechanically linking turbine to housing
Controlled with hydraulics and electronics
Has friction surface with a dampening pressure plate
Used to increase mileage by reducing 10% slip

9. Lock-up problems Can stick on, causing stalling
Can shutter on engagement
Can cause chuggle
Inop causing mileage complaints and or overheating trans.