From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Investigation into bearing failures on the Bentley rear axle pinion thrust race and proposed solutions.
| Identifier | ExFiles\Box 84\4\ scan0074 | |
| Date | 21th September 1935 | |
| To E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} x 202 Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}6/KW.21.9.35. Bentley Rear Axle Pinion Thrust Race. Even with the steel cage fitted to this bearing, we still get occasional failures of the cage of the thrust half of the bearing. Everyone is of the opinion that these failures are due to seizures of the cage or the inner race. The possible explanations of why only the thrust cage fails are, firstly, that the lubrication of a journal bearing cage is inherently better, and secondly that being further from the pinion, oil to the thrust side has to pass through the journal half. We have carried out a test to determine how easily oil gets to the thrust half of this bearing. A hole was drilled in the outer cover of the pinion housing so that any oil passing through the bearing would immediately be visible at this point. The bearing was assembled absolutely dry and the axle run at 1,000 r.p.m. of the prop. shaft. No oil had appeared after 20 minutes' running. On increasing the speed to either 2000 or 3000 r.p.m. a small amount of oil appeared in 2 minutes. We next fitted the original Hoffman bearing having oil grooves between the two outers. After 1 minute at 1,000 r.p.m. plenty of oil had been past the thrust cage. This scheme of lubrication therefore is a great improvement over that used by everyone else, namely, relying on oil being driven by the pinion right through the bearing. From all the running on Peregrine chassis and 15,000 miles on 1-B-III, we know that the oil thread will deal with the increase of oil, and have therefore instructed the bearing manufacturers to fit grooves similar to those in the original bearing. The increased lubrication we hope will prevent cage failures. The SpectreCodename for Phantom III bearing will be treated similarly. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||