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).
Bump test comparison report on the failure rates, lifespan, and fracture points of new Firth road springs versus standard pattern springs.
| Identifier | ExFiles\Box 119\2\ scan0195 | |
| Date | 1st April 1924 guessed | |
| BUMP TEST COMPARISON. Comparison of new type Firth road springs with std. pattern. SPRING FAILURES. | | No. of failures. | | Running time of tests. | |---|---|---|---|---|---| | SPRINGS. | O.S. | N.S. | Total. | | | Std. pattern. 42". | 5 | 11 | 16 | 113 hrs. 40 mins. | | New type Firth. 43¼". | 6 | 6 | 12 | 122 hrs. 10 mins. | AVERAGE LIFE OF SPRINGS. | Position of Spring. | Average life of std. type spring. | Average life of new type Firth 43¼" Spring. | |---|---|---|---|---|---| | | Firth. hrs.mins. | Woodhead. hrs.mins. | Lemoine 2 only hrs.mins. | Irrespective of make hrs.mins. | hrs.mins. | | O.S. | 10 43 | 18 52 | 18 21 | 17 8 | 18 21 | | N.S. | 9 19 | 8 53 | 18 53 | 9 47 | 19 37 | | Irrespective of position. | 9 47 | 11 36 | 18 37 | 12 5 | 18 57 | COMPARISON OF NEW TYPE SPRING CLIPS & SHEATH (F.70898) WITH STD. PATTERN. CLIPS : EFFECT ON LIFE OF SPRINGS. | | Average life of springs. | | | |---|---|---|---| | | O.S. hrs.mins. | N.S. hrs.mins. | Irrespective of position. hrs. mins. | | Std. type clips. | 18 12 | 20 18 | 19 15 | | New type clips and sheath. | 18 21 | 18 56 | 18 43 | POSITION OF FRACTURES - New type Firth springs. | Position of spring. | Fractures with std. clips. | Fractures with new sheath | |---|---|---|---|---| | | Distance to front of centre bolt. | Distance to rear of centre bolt. | Distance to front of centre bolt. | Distance to. rear of centre bolt. | | O.S. | 2" : 16" | 2" | 2" : 2" | 2" | | N.S. | 2" | 2" : 15" | 2¼" | 2¼" : 15¼" | | ||