Traction of Synthetic Traction Fluids and Its Related Rheological Properties

The traction μ_sp in the transverse direction due to spin was experimentally determined for commercially available traction oils. An increase in contact pressure increased μ_sp because of an increase in elastic strain, while a decrease in the radius of the roller in the transverse direction increased μ_sp owing to an increase in the effective shear modulus. Then, the effect of contact pressure on the maximum traction coefficient μ_max in the rolling direction was studied. Under a constant temperature, μ_max increased with increasing contact pressure, and then it decreased after reaching a peak value. The calculated results by the thermal solution based on an elastic-plastic model, using the limiting shear stress as a quadratic equation of pressure, agreed well with the experimental traction curves. This suggested that a peak value of μ_max was brought about by less than a proportional increase in the limiting shear stress with pressure.