BEHAVIOR OF TRACTION OILS UNDER IMPACT LOADS

The squeeze film forming ability of traction fluids is studied under i mpact load by a falling bearing steel ball against a stationary cylind rical surface or flat anvil made of mild steel, bearing steel, or alum inum. The effect of the pressure-viscosity coefficient and of the visc osity is investigated for plastic and elastic impact. For soft materia ls, oils with high pressure-viscosity coefficients maintain much great er surface separation under impact load. The time fraction of separati on by the oil film increases linearly with the product of the pressure -viscosity coefficient and the yield pressure of the anvil material. I t decreases with an increase in surface roughness. Similar results are observed under impact on stationary or rotating surfaces. These resul ts can be used to estimate the solidification behavior of traction oil s. In the case of the elastic impact for hard materials, the coefficie nt of restitution of the ball is influenced mainly by the squeeze film effect, which is governed by viscosity itself.