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).
Comparison table of specifications for different types of steering gear.
| Identifier | ExFiles\Box 28\3\ Scan089 | |
| Date | 7th January 1935 | |
| -2- Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}12/KW.7.1.35. Type of Steering Gear | R.R. | Marles 15/1 | Marles 17.5/1 | Marles 20.5/1 Lock to Lock Ratio Stg.Wheel to Road Wheels. | 11.9/1, 12.8/1 | 12.2/1, 12.95/1 | 14.3/1, 15.3/1 | 16.5/1, 17.7/1 S.S. Tube Movement each way. | 0.350, 0.250 | 0.350, - | 0.350, 0.350 | 0.350, 0.350 S.S. Tube set up Load lbs. | 40, 40 | 40, - | 40, 40 | 40, 40 S.S. Tube Spring Rating lbs/ins. | 820, 985 | 820, - | 820, 820 | 820, 820 Hs{Lord Ernest Hives - Chair}/F.J.Hardy. | ||