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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 tests, comparing white-metal and Vandervell bearings to standard RR alloy bearings for the Merlin engine.

Identifier  ExFiles\Box 115\4\  scan0114
Date  10th September 1940 guessed
  
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of local 'giving'. Results of tests on the single panel rig show that whereas the success of lead bronze in general depends upon its ability to stand up to high local loads for short lengths of time during the initial running-in period, when the bearing as a whole is settling down, a white-metal bearing is unable to cope with this high local intensity of loading. Local stresses result in the bearing cracking and small pieces of white metal becoming detached. Endurance running extending over 50 hours confirms that most of the cracking occurs during the first few hours and that the rate of cracking becomes progressively less as the running time increases and the bedding becomes more even. Messrs Vandervell have endeavoured without very much success to combat this effect by

(a) Relieving the bearing to the extent of .001" for 3/8" on either side of the joint face. Breaking up then commenced at the edges of the relieved portion.

(b) By providing an oval bore i.e. provision of bearing housing .002" additional clearance at the joint face in order to relieve the loading on this section. Breaking up then commenced at the bearing edges.

(c) By provision of an oval bore with barrel shaped section. Breaking up then commenced in the centre of the bore.

Further Tests.

Further tests which might be carried out but are hardly justified by the above results are (a) seizure and (b) oil shortage tests.

Conclusion. Since bearings in the standard RR alloy have a life of approximately four to five times that of Vandervell bearings, and bearings in the improved alloy about ten to twelve this before break-up commences; it appears extremely unlikely that Vandervell bearings will give satisfactory results on the Merlin.

Lov{Mr Lovesey}/AT.
  
  


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