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 of efficiency between steering nuts with .940 lead and the standard .720 lead.
| Identifier | ExFiles\Box 17\4\ Scan062 | |
| Date | 24th November 1933 | |
| X7030 To Hs.{Lord Ernest Hives - Chair} from HHC. C.c. B.E. RHC.{R. H. Coverley - Production Engineer}8/BE24.11.33. Steering Nut F.73600 (.940 lead) Steering nuts with .940 lead have been produced and comparisons taken with regard to the relative efficiency of these and the present Standard worm and nut with .720 lead. Standard Worm and Nut shew an increased efficiency of 20%, figures being as follows:- | Axial Load on nuts (lbs) | Applied Effort |||| |---|--- |--- |--- |--- | | | Present Standard .720 lead. | | Old type .940 lead | | | | Pull in lbs at 20" rad: | Efficiency | Pull in lbs at 20" rad: | Efficiency | | 300 | 2.00 | 85.92% | 3.50 | 64.00% | | 600 | 4.20 | 81.85% | 6.75 | 66.48% | | 900 | 6.00 | 85.92% | 10.50 | 64.09% | | 1200 | 9.00 | 76.38% | 13.25 | 67.74% | [Handwritten Note] R.H.C. Cannot make your latest figures on .940 lead worm agree with those we obtained RHC.{R. H. Coverley - Production Engineer} in 1928. Actually theoretically the .940 must be more efficient than the .720. Can we repeat tests | ||