Design and development of a ball impact apparatus for the direct measurement of lubricant friction under high pressures and shear rates

The development of a new ball impact apparatus for the measurement of the t raction behaviour of solidified lubricants is described. The normal and tan gential forces between an oily plate and an obliquely impacting ball were m easured directly on two different forms of apparatus by means of piezoelect ric transducers. From the measured forces the coefficient of friction durin g impact could be calculated. For one particular oil, Santotrac 50, a full set of results is given and these are shown to be in good agreement with va lues reported previously by others using different forms of experimental eq uipment.