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).
Results of piston testing, comparing different types, their performance, and failures.
| Identifier | ExFiles\Box 86\2\ scan0144 | |
| Date | 10th November 1933 | |
| X236 To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} C. c. E.{Mr Elliott - Chief Engineer} By.{R.W. Bailey - Chief Engineer} c. Mx.{John H Maddocks - Chief Proving Officer} PN.{Mr Northey} c. Bn.{W.O. Bentley / Mr Barrington} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}10/KT.10.11.33. BENTLEY PISTON POSITION. We attach a chart showing the test running carried out on pistons up to date. Briefly the position is that so far we have not been able to make one of our own pistons last more than fifteen hours at maximum B.H.P. and revs. before signs of failure became evident. Up to date we have tried four types: We have had in turn, skirt failure, gudgeon pin boss failure, and finally, after curing these two, failure of the ribs in the head. Two tests have now been run on the latest R.R. piston to LeC.3675 with strengthened gudgeon pin bosses. On the first test all six cracked after five hours running, but we attribute this failure to a heat treatment that these pistons had received. We believe that it was this heat treatment that caused the pistons to fail on the last 10,000 miles test, as it was used for the first time then. On the second test, two pistons were found cracked after fifteen hours running. We can therefore say that the last alteration to the gudgeon pin boss has altered the location of the crack, but has not prolonged the life of the piston before cracking starts. We have a set of Aerolite pistons that have run nineteen hours without cracks developing. We know that if a piston will stand nineteen hours of this hammering, it will outlast several of the existing engine components that have not given trouble on the road - i.e. we believe the Aerolite pistons will run 10,000 miles in France without failure. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||