automotive engineering Automotive engineering, along with aerospace engineering and naval architecture, is a branch of vehicle engineering, incorporating elements of mechanical, electrical, electronic, software, and safety engineering as applied to the design, manufac ...

, drawbar pull is the amount of horizontal force available to a vehicle at the drawbar for accelerating or pulling a load. Drawbar pull is a function of

velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...

, and in general decreases as the speed of the vehicle increases (due both to increasing resistance and decreasing

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...

gear ratio A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage. Gear teeth are designed to ensure the Pitch circle diameter (gears), pitch circles of engaging gears roll on each other without slipping, pr ...

s). Drawbar pull is the difference between

tractive effort As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. In railway engineering, the term t ...

available and tractive effort required to overcome resistance at a specified speed. Drawbar pull data for a vehicle is usually determined by measuring the amount of available

tractive force As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. In railway engineering, the term tr ...

using a

dynamometer A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed ( RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by ...

, and then combining that data with coastdownSAE J1263, Road Load measurement and Dynamometer Simulation Using Coastdown Techniques, dated January 2009. data to obtain the available drawbar pull force at each speed.

References

{{reflist Automotive engineering