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).
Calculation sheet for a Silver Ghost type Nut & Worm with a 1.125 lead, detailing loads, efforts, and efficiencies.
| Identifier | ExFiles\Box 38\1\ Scan176 | |
| Date | 13th March 1926 guessed | |
| SILVER GHOST TYPE NUT & WORM 1.125 LEAD The following table gives the loads and corresponding efforts required to give efficiencies the same as laid down for the new .720 lead Nut + Worm. Actually the efficiency with the increased lead should be higher but the high efficiency is not so essential with the more reversible steering. Diagram showing force P at 20" RAD. and Load W. Table of values: LOAD W. lbs. | Effort P. | EFFICIENCY % 1200 | 14.05-15.2 | 76.5 - 70.6 900 | 10.15-10.95 | 79.4 - 73.7 600 | 6.25-7.02 | 86 - 76.4 300 | 3.125-3.52 | 86 - 76.4 | ||