Abstract
Increasing oil price and environmental awareness have driven legislative limits and heightened consumer demands for vehicles with improved fuel economy. To achieve this goal, it is not only necessary to make internal combustion engines more efficient, it is also necessary to have a fundamental knowledge about power losses in the powertrain.
Front wheel disconnection is seen as the best choice to decrease fuel consumption for all wheel drive vehicles. This trend comes from the USA and seems to be founded on corporate average fuel economy (CAFE) regulations. Initial calculations have led to the suspicion that lifetime fuel saving may not justify the higher cost of front wheel disconnection.
In 1995 the R&D department of Magna Steyr Powertrain began to measure and simulate spin losses of transfer cases to quantify this problem.
The theses [1] of the author have led to structured research. To date, three gear boxes have been completely analyzed. One of them is a prototype of our company which is shown in Figure 1.
These transfer cases have been built up as single offset, torque on demand systems with a High / Low range shift mechanism. The front axle drive is achieved by a multi plate clutch.