14-04-2011, 10:46 AM
in engineering Traction refers to the maximum frictional force that can be produced between surfaces without slipping and The units of traction are those of force, or if expressed as a coefficient of traction
Definition:
a physical process in which a tangential force is transmitted across an interface between two bodies through dry friction or an intervening fluid film resulting in motion, stoppage or the tranmission of power and The traction produced by a vehicle if expressed as a force is synonymous with tractive effort, or tractive force
Factors affecting tractive coefficient
Traction between two surfaces depends on several factors including:
Material composition of each surface.
Macroscopic and microscopic shape (texture; macrotexture and microtexture)
Normal force pressing contact surfaces together.
Contaminants at the material boundary including lubricants and adhesives.
Relative motion of tractive surfaces - e.g. a wheel on gritted ice when in motion may displace the grit and melt the ice - causing loss of traction. Current traction control systems do not work on untreated ice.