Tractive effort is the force generated by a vehicle's engine or motor in order to generate motion through tractive force. Tractive effort differs from tractive force, which is the actual force applied at the road surface, by the amount of rolling resistance present. In mathematical terms,
Tractive Effort = Tractive Force + Rolling Resistance
Tractive effort is a function of vehicle speed and can refer to tractive effort available or tractive effort required:
- Tractive effort available: maximum tractive effort of a vehicle as limited by the available power (or at low speeds, friction).
- Tractive effort required: the amount of tractive effort required to overcome the resistive forces caused by rolling resistance, air resistance, grade, and/or drawbar pull.
- SAE J2188, Commercial Truck and Bus SAE Recommended Procedure for Vehicle Performance Prediction and Charting, dated October 2003.