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 report for 40/50 front springs, detailing test conditions and fracture analysis.
| Identifier | ExFiles\Box 119\2\ scan0207 | |
| Date | 9th October 1924 | |
| BUMP TEST. Re. 40/50 FRONT SPRINGS TEST OF LATEST PATTERN WOODHEAD 12½% TYPE SPRINGS (F71790/1). CONDITIONS: 2" CAMS SET AT 180°. DRUM MAKES 105 R.P.M. TYRES AT 65 LBS/SQ". LOAD ON FRONT OF CHASSIS = 1000 LBS. TABLE DATA: DETAILS OF SPRING: No.003. NEAR SIDE. F71790. 1100 LBS. FLEXION: COMPRESSION = 1.67", REBOUND = 2.57". POSITION OF FRACTURES. (Diagram showing fractures M, N, O, P, R, S on a leaf spring) | FRACTURE | POSITION OF LEAF | POSITION OF FRACTURE FROM CENTRE BOLT | APPROXIMATE RUNNING TIME (HRS - MINS) | THICKNESS OF LEAF | BRINELL AT FRACTURE | |---|---|---|---|---|---| | M | BOTTOM | 2" TO FRONT | 10 - 12 | .222" | 375 | | N | 7TH (FROM TOP) | 2.5" TO FRONT | 28 - 4 | .230" | 375 | | O | 7TH (FROM TOP) | 4" TO REAR | 28 - 4 | .230" | 363 | | P | 7TH (FROM TOP) | 8.5" TO REAR | 28 - 4 | .230" | 388 | | R | 8TH (FROM TOP) | 2" TO REAR | 29 - 34 | .226" | 415 | | S | TOP | 7" TO REAR | 32 - 49 | .285" | 352. | DETAILS OF SPRING: No.004. OFF SIDE. F71791. 1150 LBS. FLEXION: COMPRESSION = 1.67", REBOUND = 2.48". POSITION OF FRACTURES. (Diagram showing fractures T, U, V on a leaf spring) | FRACTURE | POSITION OF LEAF | POSITION OF FRACTURE FROM CENTRE BOLT | APPROXIMATE RUNNING TIME (HRS - MINS) | THICKNESS OF LEAF | BRINELL AT FRACTURE | |---|---|---|---|---|---| | T | BOTTOM | 2" TO REAR | 17 - 56 | .230" | 375 | | U | BOTTOM | 2" TO FRONT | 23 - 2 | .230" | 375 | | V | TOP | 10" TO REAR | 23 - 2 | .285" | 331 | | ||