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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).
Engine bearing test #5, detailing the procedure, conditions, and results including dimensional changes.

Identifier  ExFiles\Box 173\2\  img228
Date  21th February 1934
  
15

February 21, 1934

ROLLS ROYCE ENGINE BEARING TESTS
(Continued)
Test #5

A test was run this date on an Allison center main bear-ing specification 55-40 (60% Cu, 40% lead, 1% silver). Other bearings, intermediate and end, were the same bearings as used on Tests #1 and #3. All bearings used Rolls Royce type groov-ing and lubrication. Crankshaft used was #4, previously used on tests #2 and #4. The auxiliary booster oil pump was not used as it was not necessary to maintain 68-70 lbs. per sq. in. at 3500 R.P.M.

The bearings were run-in under approximately the same conditions as with #3 test up to 3500 R.P.M. The #3 test at 3500 R.P.M. was then duplicated, consisting of a 15 minute run at 3500 R.P.M. followed by 20 diving tests of 30 seconds at 3500 R.P.M. and 1 minute at 2250 R.P.M. This was followed immediately by 15 minutes running at 3500 R.P.M. giving a total time at 3500 R.P.M. of 40 minutes. The bearing temperature averaged about 8°C higher than in #3 test (70-30 center main) and the torque load was about 1% (about 1.2 H.P.) less.

The bearing surface was slightly better than on any of the 70-30 bearings tested and the crankshaft appeared and felt smoother than after previous Allison bearing tests. The amount of lead sweated out was less.

Center main bearing dimensions were as follows:

Before Test After Test Wear
Max. diameter 2.9995 3.0017 .0022 Max.
Av. diameter 2.9995 3.0007 .0012 Av.
Av. clearance 0.0046 0.0059
  
  


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