Traktion

Traktion is a term used in German and in technical contexts to denote the transfer of a driving force from a source to a load through friction between surfaces. In physics and engineering, traction describes the grip or adhesive force that allows a body to move on a surface without slipping. The available tractive effort is determined by the normal force, the coefficient of friction (adhesion), and surface conditions.

Road vehicles: On tires, traction is the essential factor for acceleration, braking, and cornering. Road conditions (dry, wet, snow, ice), tire design, and load affect traction. Traction control systems regulate engine torque and braking to prevent wheel slip; all-wheel-drive layouts can distribute torque to improve traction. ABS interacts with traction to maintain steering control during braking.

Railways: In railway engineering, traction refers to propulsion and braking forces transmitted from rolling stock to rails. Electric traction uses traction motors powered by an overhead line; diesel traction uses internal combustion engines. Key metrics include tractive effort and continuous tractive effort; wheel-rail adhesion governs the maximum sustainable force; wheel-slip control systems monitor and limit slip.

Medicine: In German medical terminology, Traktion or traction refers to deliberate pulling of a limb or body part to align fractures or dislocations. This can be skeletal traction (weights and pins) or skin traction (straps with weights). Traction is often part of staged fracture management and can be temporary or adjunct to surgical fixation.

Etymology: from Latin trahere "to draw", via French traction and German Traktion; in German, the spelling retains "k" in technical terms.