Before the hydrodynamic clutch was further developed as torque converter, its task was the interference fit join between engine and automatic gearbox and substituted for the starting clutch. It operated exclusively with liquid friction and, therefore, was free of servicing and free of wear (except for changing the oil). The hydrodynamic clutch is no longer used in combination with the automatic gearbox of cars any more.
How it works
In the clutch housing between engine and automatic gearbox a rotating case is solidly connected with the crankshaft. The case is constantly supplied with gearbox oil via the shaft connection with the gearbox. The impeller with its radially arranged blades is integrated solidly in the case on the gearbox side (to the right). Towards it, on the engine side (to the left), the turbine wheel is arranged which is freely rotate able in the case and has a similar construction. It is connected with the gearbox shaft through a tooth system. The condition of the turbine wheel and its tooth system are very well comparable to that of the clutch disc. During the initial drive, the complete case turns together with the impeller blades around the stationary turbine wheel. However, different than the dry clutch, the torque is transferred by liquid friction.
During the initial drive oil from the impeller hits, fling outwardly and in rotation direction, the at that moment still stationary turbine wheel and is slowed down against the rotation direction of the impeller and is diverted inwards. There it is again diverted, by the rotary impeller, and again accelerated. In contrast to the torque converter, the hydrodynamic clutch does not increase the torque.
The biggest slip between impeller and turbine wheel appears during the initial drive. 06/08