For the four power polynomial cam in question a separation of 0.4mm was maintained mechanically over the base circle region. The ‘blips’ in the traces of Figure 5 represent therefore the commencement and cessation of contact between cam and follower which were associated with ramp regions designed for a constant velocity of lift. The particular sector of interest is from 60°(the beginning of the opening flank) through 0° (the cam nose) to +60° (the end of the closing flank). The arrangement under examination was symmetric and the healthy film thickness over the flank regions, the modest film over the nose and the two critical areas of ‘zero’ lubricant firm-thickness are evident in Figure 5(a).