The cost of transmission development, especially for automatic
transmissions, requires special methods for evaluating both power
transfer and fuel consumption. Previous methods have deviated
substantially from actually driving conditions; consequently, data
for this investigation was based on driving cycles consisting
of:
1) acceleration at full engine loading
2) driving at constant speeds ranging from 35 to 60 km/h
3) braking at 1 m/s2 deceleration
Test results on a Diesel-equipped, city bus indicated:
1. Automatic transmissions are advantageous and economical,
especially at high speeds.
2. Manual shifts can be improved through shorter gear-shifting
times.
3. Potential use of unstepped transmissions are promising if
optimal means of control are incorporated.
4. Theoretically, energy storage can provide significant
savings, but the complexity of its practical application makes its
implementation unlikely.
Although the tests were run on a city bus, the analytical
approach can be applied to more complicated driving patterns of
other heavy vehicles.