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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).
Failure analysis report on an Allison BZ/L bearing material.

Identifier  ExFiles\Box 115\1\  scan0322
Date  23th April 1937 guessed
  
Bearing Material. Allison BZ/L. Brinell No. 35.1

Composition.
Copper ........ 70%
Lead .......... 30%

½% of silver is included in the total.

Clearance (cold) when fitted = .0035".
Clearance (hot) last check prior to failure = .0045".

V.C.M. sleeve. Brinell No. 715.

Failure occurred at completion of 4 hour run at 3150 RPM. i.e. 2500 lbs/sq.in. load.

Type of Failure.

The bearing gave plenty of warning before failure occurred.

Many times during the running local seizures took place, sometimes resulting in as much as a 30° to 40°C. rise in temperature being recorded by the thermocouple, but after each of these seizures the bearing recovered without treatment; no solid seizure occurred at all and the bearing was removed on account of it having large area lead wiped.

TOTAL RUNNING TIME OF BEARING ..... 39 hrs. 49 mins.
  
  


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