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 and material properties of a Bentley Contact Breaker Spring.
| Identifier | ExFiles\Box 3\4\ 04-page353 | |
| Date | 23th June 1933 | |
| To HY.{Tom Haldenby - Plant Engineer} from E.{Mr Elliott - Chief Engineer} c.c. Mr. Hs.{Lord Ernest Hives - Chair} Haywood Bentley Contact Breaker Spring. We have no objection to the use of carbon steel as such for the make and break spring if it will do the job but this is the second attempt by Watford to produce a suitable spring for Bentley which has fallen flat and time is growing short. There is no doubt that the stress as well as the number of reversals in this spring is more than anything we have had before, either on 20/25 Gillot springs or the Peregrine for the following reasons:- (a) The Bentley is of the short fixed ended type of spring like Delco, in which there are unknown stresses due to centering and clamping the fixed end which would not occur on the 20/25. (b) Compared with the Delco as used on Peregrine, the Bentley lever is .2 inches longer and for the same pressure at the points the spring stress will be more. (c) We doubt whether the spring which gave way was any softer than is usually employed. Another spring from the same batch shows actually a higher Brinell figure than obtained from a Delco spring. Spring. Brinell No. Peregrine Delco -- 493. Bensport Watford -- 542 These springs are all soft enough to take a permanent set. We did not suggest that the steel had altered its temper as a result of work but that the required stress was more than the normal material would maintain. E.{Mr Elliott - Chief Engineer} | ||