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).
Data for Weller steering for the Bentley.
| Identifier | ExFiles\Box 28\2\ Scan174 | |
| Date | 1st May 1933 | |
| DATA FOR WELLER STEERING FOR THE BENTLEY. Existing box ratio of Phantom to which Marles steering has already been fitted, 12.7-1. Best results on this car obtained with the Weller gear having 1.1/32" lead, helix angle of 10° 25', 17.5-1 Box ratio. Therefore presumably this helix angle will be best for the Bentley. But this means an increase in steering ratio of about 40% which is undesirable on a sports car but appears to be unavoidable if the same lightness of steering is to be maintained since the Marles Weller gear efficiency in the forward direction is only about 50%, whereas the Rolls-Royce type of worm and nut is 75% efficient. It would avoid delay if, should you decide to supply the 17.5-1 box ratio, you could produce with the box two pendulum levers, 8.00" and 9.5" long respectively, with the top end made to suit your splines and broached accordingly, the bottom end to be left blank for the fitting of our ball ends. | ||