Rolls-Royce Archives
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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).
Bearing failures and recommendations for improved designs based on test results.

Identifier  ExFiles\Box 114\2\  scan0053
Date  21th July 1934
  
-2-

After 50 hours signs of overload failure of the roller track were visible and the journal load was therefore halved. After 100 hours the scruffing of the rollers and tracks was very marked and would eventually cause failure of the surfaces. We were able to see a similar type of caged roller bearing that had run 400 hours. The surfaces were polished and showed no scruffing.

We think the thrust failure is due to material as the capacity of this half of the bearing should be adequate, and that a cageless roller journal bearing over-running at high speeds will not be satisfactory. Fitting a cage and decreasing the number of rollers will not be any better than a ball bearing.

We think that when Hoffman ran their bearing and experienced an unusual temperature rise, they ran with journal load only. In that case the thrust balls will skid on 3 tracks and get hot, but this condition never arises on the road. We have an example of the original Hoffman double row ball bearing mounted so that one row took both journal and thrust load, in which a ball in the row that has done no work has failed due to spinning.

The SpectreCodename for Phantom III axle is shown with a combined ball and roller bearing. The axle is the same as the Vulture on which we have fitted a larger edition of the present Bentley bearing. This bearing has successfully completed 110 hours at 3000 r.p.m. twice Vulture top gear loads. We recommend fitting this bearing - a Ransome & Marles 2MDJT35 - to the SpectreCodename for Phantom III axle and think we are safe in saying that no trouble will be experienced. We have done considerable gearbox dynamometer running on the Vulture without any signs of overload failure.

We are running the Bentley bearing 100 hours at 4500 r.p.m. and will report on this shortly.

Hs{Lord Ernest Hives - Chair}/H.Grylls.
  
  


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