trekkracht

Trekkracht is a term used to describe the force that acts to pull a load in the direction of motion. In physics and engineering it refers to the pulling component of forces generated by a machine, vehicle or mechanism, as opposed to opposing forces such as drag, gravity on an incline, and rolling resistance. The amount of trekkracht available depends on the power source, the transmission of power to the load, and the friction between contact surfaces.

At the wheel level, trekkracht can be expressed as F = T_wheel / r_wheel, where T_wheel is the torque delivered to the wheel and r_wheel its radius. In practice the usable trekkracht is the lesser of the drivetrain-limited torque and the adhesion-limited maximum, μN, with μ the coefficient of friction and N the normal force. On trains, locomotives are rated by tractive effort in kilonewtons (kN). In road vehicles, manufacturers publish peak or continuous tractive force, which, after gearing, translates into wheel force to overcome rolling resistance and aerodynamic drag.

Trekkracht is crucial for performance because it governs acceleration, the ability to start moving on an incline, and towing capacity. It is affected by surface conditions (wet or icy surfaces reduce friction), tire or wheel condition, weight on the drive axle, gearing, and traction control systems. In railway and automotive engineering, maintaining adequate trekkracht while preventing wheel slip is a central design and control challenge.