Torque Converter

Torque Converter


The mechanical power flow in the gearbox starts at the connection point between the torque converter and flywheel. When the engine is running, the converter housing (pump) turns with the engine speed. With rotation, the converter multiplies the engine torque and transfers it to the drive shaft. The drive shaft forms the main connection for mechanical operation of the gearbox.

Brief description of components
To suit engine with higher torque, the automatic gearboxes have different levels of power. The automatic gearbox differ, e.g., in that they have different torque converters.
Depending on the engine version, the following sizes of torque converter are used:
- Diameter 230 mm for 4-cylinder engines
- Diameter 240 mm for 6-cylinder engines

The torque converter is equipped with a turbine wheel damper. The turbine wheel damper improves the values for noise, vibrations and roughness when the converter lockup clutch is actuated in the lower engine speed range.

System functions

Slip on the converter lockup clutch
The converter lockup clutch leads to an improvement in the fuel consumption. Depending on the vehicle, engine and gearbox parameters, the following operating modes are available:
- OFF mode
In the OFF mode, the converter lockup clutch does not engage. There is permanent slip in the torque converter (slip greater than 50 rpm).
- ON mode (EC)
In the ON mode, (EC) the converter lockup clutch is set to a slip of 40 rpm. (EC stands for electronically controlled converter lockup clutch)
- ON mode (closed)
In the ON mode (closed), there are two functions for the converter lockup clutch:
- Low slip (0 to 10 rpm)
- Fully closed (no slip)

Notes for Service department

Diagnosis instructions

Relevant faults in the converter lockup clutch
The following faults are treated in the test module:
- 56C1 Converter lockup clutch: stuck in open position
- 56C2 Converter lockup clutch: stuck in closed position

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