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).
Table detailing specifications for two types of Springfield steering systems.
| Identifier | ExFiles\Box 154\3\ scan0009 | |
| Date | 28th January 1927 | |
| Oy2-E-12827 -2- January 28, 1927 Type of Steering Pitch line diameter Overall ratio Steering wheel to front wheel at centre position. Helix angle of thread at pitch line "Pressure Angle" of thread Springfield 1.5" 1.500" 13.20 8° 40' 14-1/2° Springfield 1-5/8" 1.625" 13.20 8° 0' 14-1/2° COPY Oy. MO/E Stop | ||