Introduction to Diesel Train Physics

Aim - this section describes the general key physics of diesel Locomotives operation.



Transmission Systems

Diesel Electric - Power

Diesel Electric - Tractive Effort


Load Hauling Performance

Diesel Mechanic Transmission - Power and Tractive Force

Useful References


The Diesel locomotive as the name implies is driven by a diesel engine. The diesel engine, or prime mover, produces the power to drive the locomotive forward and pull the train. The power produced by the prime mover is transmitted to the driving wheels, by a number of different transmission systems including mechanical transmission, electric traction motors, or hydraulic drive systems. The diesel typically is cheaper to operate then a steam locomotive, and some of the other advantages include the fact that they can be operated in multiple units with a single driver, they can be started or sindexped almost instantaneously compared to a steam locomotive which requires time to build up steam.

To understand the performance of a diesel locomotive the following three subjects will be considered:

  • Diesel Transmission Systems
  • Power
  • Tractive Effort
  • Adhesion

Once the above three elements are considered in conjunction with the train resistances, we can model the overall performance of the train.


Transmission Systems

Unlike an electric motor or a steam engine, a diesel engine is not well suited to driving the locomotive wheels directly. As a result power from the prime mover is transferred to the wheels by an intermediate transmission system. The four types of transmission system widely employed are: