b) Economy
The figure shows a comparison of the efficiencies of different transmission concepts. The transmission efficiency of the manual 5-speed transmission, particularly in the lower part-load range, is superior to the remaining systems since no setting hydraulic has to be operated. In the central part-load range, the U transmission has a slight advantage compared to ATs. The high performance hydrostatic transmission has significantly lower values due to running blind outputs when starting and the losses in the hydrostatic control circuit.
The total efficiency of engine and transmission, apart from the transmission efficiency, is essentially determined by the possibility to operate the engine in a low fuel consumption range. This is possible by a nearly continuously variable conversion and a large spread. Compared to stepped transmissions, the continuously variable transmission concept receives a better evaluation on the basis of range of transmission ratios which can be realised:
U transmission: iges up to 7
Hydrostatic Transmission: iges up to 25
Passenger car Manual and Automatic Transmission: iges up to 5
Truck Group Transmission: iges up to 15