automotive engineering Automotive engineering, along with aerospace engineering and naval architecture, is a branch of vehicle engineering, incorporating elements of Mechanical engineering, mechanical, Electrical engineering, electrical, Electronic engineering, electro ...

, drawbar pull is the amount of horizontal force available to a vehicle at the drawbar for

accelerating In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Acceleration is one of several components of kinematics, the study of motion. Accelerations are vector quantities (in that they have magnit ...

or pulling a load. Drawbar pull is a function of

velocity Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical q ...

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

transmission Transmission or transmit may refer to: Science and technology * Power transmission ** Electric power transmission ** Transmission (mechanical device), technology that allows controlled application of power *** Automatic transmission *** Manual tra ...

gear ratio A gear train or gear set is a machine element of a mechanical system formed by mounting two or more gears on a frame such that the teeth of the gears engage. Gear teeth are designed to ensure the Pitch circle diameter (gears), pitch circles of e ...

s). Drawbar pull is the difference between

tractive effort In railway engineering, the term tractive effort describes the pulling or pushing capability of a locomotive. The published tractive force value for any vehicle may be theoretical—that is, calculated from known or implied mechanical proper ...

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 using a

dynamometer A dynamometer or "dyno" 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 the dyna ...

, 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