Power transmission
Internal combustion engine traction - Overall architecture

The mechanical energy available on the crankshaft of an internal combustion engine is characterized by the engine torque curve (N · m) as a function of speed (rpm) (figure 3a). Maximum torque is delivered at maximum speed, so at speeds close to idle, torque is minimal. Comparing this characteristic with that of hook force (tractive effort in kN) as a function of speed (km/h) for a rail vehicle (the same applies to a motor vehicle, figure 3b), it is easy to see that the requirement is exactly the opposite: maximum motor torque must be applied from...