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 failures and test conditions for the Conqueror engine.
| Identifier | ExFiles\Box 173\1\ img073 | |
| Date | 15th January 1934 | |
| - 3 - HS{Lord Ernest Hives - Chair} Conquerors has been obtained with balance weight crankshafts, semi-balanced type, similar to R.{Sir Henry Royce} & Kes. types, which was introduced in the days of white metal bearings owing to repeated failures of crankcase center bearing panels. Test conditions under which m.b. bearings fail are much more severe than in the case of the Conqueror. For latter, test conditions stipulate that engines should be run up to normal power and speed, throttle being fixed and 30% overspeed = 3400 R.P.M. run in stages of 20 second duration. after each period normal speed and power conditions are restored for two minutes and repeated until five minutes total running has been completed. Grooveless bearings are used with six feed holes for lubrication, holes being equally spaced in top and bottom halves with annular groove externally for oil supply, it would appear that this arrangement provides greater oil pressure at bearing, with grooves oil particularly under extremely high temperature conditions can readily flow out of bearings. Certain failures have been experienced on thrust bearings which are arranged at front end of crankcase, being twice the width of Kes longest bearing, and it appears that failures were brought about due to crankcase distortion which owing to length of bearing, would considerably reduce clearance and bring about failures. This trouble was overcome by stiffening of forward end of crankcase and slightly increasing bearing clearances. I did not see any bearings which had failed but gathered failures were of an exactly similar nature to those we have experienced. I examined some main bearings out of development engines which had run equivalent tests to H.R. endurance, and cannot admit they were any better than we are accustomed to; after test, main bearings which had run for long periods were in similar condition in every way to Kes (center excepted). The connecting rods which are articulated type give no bearing trouble, conditions were exactly like bearings we expect to see after long periods of running, having a beautiful black bloom on surface, being quite different to main bearings which are bright and scratched due to metallic contact. The material structure of lead bronze is close and homogeneous and resembles Kes connecting rod bearings which contain 1% Tin, while Wright's are led to believe that bearings supplied is straight 70/30 composition. I doubt it owing to fine material structure and feel certain that tin, zirconium or some other content has been used to prevent segregation and oxidation. Design points of Conqueror will be dealt with in my next report. Hm{Capt. W. Hallam - Head Repairs} has complete schedule of type test for both air cooled and liquid cooled engines which no doubt he will forward in due course. Typed 1/15/34 RHC{R. H. Coverley - Production Engineer}:ms R.{Sir Henry Royce} H.{Arthur M. Hanbury - Head Complaints} Coverley | ||