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).
Specification for Wraith III speedometers, detailing scale calibration and testing parameters.
| Identifier | ExFiles\Box 165\2\ img203 | |
| Date | 15th June 1939 | |
| Specification EL.8/9. 15.6.39. WRAITH III SPEEDOMETERS. The scale to be set out as hereunder :- True Speed. (m.p.h.). 10 20 30 40 50 60 70 80 90 Indicated Speed. (m.p.h.). 10 - 12 20 - 22 30 - 32 40.5 - 42.5 51 - 53 61.5 - 63.5 72 - 74 82.5 - 84.5 93 - 95 Flex. Speed 730 r.p.m. at 60 m.p.h. for mileage recorder. Each instrument will be tested at :- 714 r.p.m. when indicated speed must be 60 -0, +2 m.p.h. 1062 r.p.m. when indicated speed must be 90 -0, +2 m.p.h. ROLLS-ROYCE LIMITED. | ||