Fluid Coupling Torque Multiplication

1. Fluid CouplingTorque 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. Impeller 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 Operation

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.