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).
Laboratory report detailing fractures in Silico-manganese road-spring main-plates following a bumper test.
| Identifier | ExFiles\Box 154a\4\ scan0062 | |
| Date | 7th December 1937 guessed | |
| ROLLS-ROYCE LABORATORY REPORT: M.1486/1. Spring No.1. x 2 M.1486/2. Spring No.2. x 2 Firths' Silico-manganese road-spring main-plates. Fractured on bumper test. Starting point of fracture in decarburised upper surface indicated at "x". | ||