Abstract
This paper describes a new disc machine which has three discs, the central one supported by air bearings. This configuration lends itself to simple manufacture and easy inspection of the disc surfaces. It is chiefly intended for very accurate friction measurements near the rolling point, but film thickness and other measurements can also be made. Two sets of results obtained with the machine are reported. The first, on mineral oils, shows that as the temperature is raised the effective viscosity becomes less dependent on speed. It is thought that this may be associated with the relaxation time. The second, on a silicone fluid, shows that the same power law which explains the poor film thickness can also explain the apparent loss of viscosity at the centre of the contact.
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