Bump test comparison of new Firth road springs against standard pattern springs, analysing failures, life, and fracture positions.
| Identifier | ExFiles\Box 73\2\ scan0316 | |
| Date | 1st April 1942 guessed | |
| BUMP TEST COMPARISON. Comparison of new type Firth road springs with std. pattern. SPRING FAILURES. | SPRINGS. | No. of failures. | | | Running time of tests. | |---|---|---|---|---| | | O.S. | N.S. | Total | | | Std. pattern. 42". | 5 | 11 | 16 | 113 hrs. 40 mins. | | New type Firth. 43½". | 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 43½" 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" | 2½" | 2½" : 15¾" | | ||
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).