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).
Bench tests comparing the efficiency of different lead steering worm and nut designs.
| Identifier | ExFiles\Box 17\3\ Scan200 | |
| Date | 22th March 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} OY. c. to DA.{Bernard Day - Chassis Design} X7430 Hs{Lord Ernest Hives - Chair}/Eml/LG22.3.28. STEERING. X. 8430 X. 7430 X. 8420 We have been running one of the latest .900 worms with the longer rocking lever in the box. As we have already reported, we had some difficulty in making this worm give a good efficiency owing to the fact that it has a 50% greater area of contact than the .720 worm, and we found it more difficult to get an even bedding over the increased area. Our results so far indicate that the performance of this unit will not be very different from that of the present standard .720 worm and nut. It seems much the same both for ease of parking and the transmission of road shocks. It does not stick when parking, but we never have nay trouble in this respect with the present standard .720 lead now we have learnt how to make them properly. We have carried out further bench tests carefully comparing the average 'parking' and 'joggling' efficiencies of the .940 and .720 lead worm and nuts. The results are as follows, though itis difficult to obtain consistent figures. Efficiency. .720 lead. .940 lead. Helix Angle 14° 15' 14° 20' Parking - 55% 66.0% Joggling - 72% 74.0% This bears out the report of the Repair Dept. that they consider the .940 steerings quite as immune from joggles as the .720 contd :- | ||