Torque Converter Clutch (TCC)

Fig 1: Torque Converter Clutch (TCC)

Courtesy of DAIMLERCHRYSLER CORP.

The TCC was installed to improve the efficiency of the torque converter that is lost to the slippage of the fluid coupling. Although the fluid coupling provides smooth, shock-free power transfer, it is natural for all fluid couplings to slip. If the impeller (3) and turbine (5) were mechanically locked together, a zero slippage condition could be obtained. A hydraulic piston (6) with friction material (7) was added to the turbine assembly (5) to provide this mechanical lock-up. See Fig 1.

In order to reduce heat build-up in the transmission and buffer the powertrain against torsional vibrations, the TCM can duty cycle the L/R-CC Solenoid to achieve a smooth application of the torque converter clutch. This function, referred to as Electronically Modulated Converter Clutch (EMCC) can occur at various times depending on the following variables:

1. Shift lever position
2. Current gear range
3. Transmission fluid temperature
4. Engine coolant temperature
5. Input speed
6. Throttle angle
7. Engine speed