Abstract
To operate at high temperatures, up to 1100°F, bearings must be protected against two sources of early failure: formation of red rust by oxygen attack on the surfaces in either rolling or sliding contact, and rapid wear by local seizure (scuffing) of the cage surfaces in sliding contact with other elements. The first function can be filled for all-ferrous bearings by an atmosphere consisting of a mixture of air and an organic vapour which acts as a reducing agent at elevated temperatures. The performance of the second function requires constituents or additives that form anti-scuffing films.
An olefine oxide polymer was found to be a satisfactory reducing agent over the whole temperature range. Conventional extreme pressure (e.p.) additives are effective in preventing scuffing up to about 900°F. Above 900°F the polymer forms an organic film which itself gives some protection against scuffing. Size 206 tool steel bearings have been operated for 100 hours at 1000°F, 10 000 rev/min under considerable radial and axial load; and for 22 hours at 1100° F. With the bearings available thus far, maximum loads are dictated by softening of the metals above 900°F.
These high temperatures create special problems in the design of the test equipment with respect to fits, warping and dimensional changes. The rig and procedures used in this work are described.
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