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).
The cause of 3½ Litre Bentley piston failures and proposed solutions with an external supplier.
| Identifier | ExFiles\Box 82\1\ scan0280 | |
| Date | 26th October 1933 | |
| To Wor.{Arthur Wormald - General Works Manager} From Hs.{Lord Ernest Hives - Chair} c. to O.{Mr Oldham} c. to E.{Mr Elliott - Chief Engineer} c. to Ry. c. to Mi. 3½ Litre Bentley Piston Failure. We are glad to say that we are now able to form a very definite idea of the cause of the piston failure on the last car in France. The failure occurred due to the fracture of the gudgeon pin boss and was not connected with the flexibility of the skirt. We found that a crack had started in a similar place on No.5 piston and in going over some of those which we have tested on the bench we found another piston in No.2 cylinder which had a similar crack. E.{Mr Elliott - Chief Engineer} has given us a modification to strengthen up the gudgeon pin boss which is being pushed forward as quickly as possible in order to get a set of pistons running. When we first ran into piston troubles on this car we got into touch with the Aerolite Piston Co., who are specialists and produce about 10,000 pistons per week of different types. With no obligation to us, they produced dies and supplied us with one dozen pistons. A set of these have run for 21 hours under very severe conditions (we have reproduced our own piston failures in 15 hours). The Aerolite representative has called at the Works and from the experience of running the first set he is proposing to send us a modified set. We propose carrying on with these pistons in parallel with our own tests. They claim, and as far as we have gone it appears to be justified, that we shall obtain more power and we believe less heat to oil which we should be grateful for. We feel relieved now that we are able to see how the fracture occurred as a piston failure is likely to smash up the whole engine it is the last part we wish to fail. Hs.{Lord Ernest Hives - Chair} | ||