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).
Steering system tests, specifically a larger diameter worm and nut, and recommendations for future design.
| Identifier | ExFiles\Box 68\1\ scan0024 | |
| Date | 14th March 1928 | |
| To OY. from Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} 48430 Hs{Lord Ernest Hives - Chair}/Rn{Mr Robinson}4/LG14.3.28. STEERING. We have been running the larger diameter worm and nut and the 900 lead. Although our tests have not been sufficiently extended to pass a considered opinion upon this unit we can give you the following information :- (1) The worm and nut is exceedingly difficult to produce owing to the very large area of thread over which a good bedding is required. (2) The steering did not seem to be any lighter when shunting than our present steering, nor did it seem to give any greater immunity from road shocks. Personally, I have come to conclusion that it is quite impossible to make a steering that will be reversible and at the same time give immunity from road shocks. Our tests have shewn us that we always get a greater apparent co-efficient of friction when we are shunting than when we are sustaining joggles, and in consequence, I am more than ever convinced that the right way to produce a satisfactory steering is to use a worm and nut with a helix angle of about 10° and then gear it down to the required ratio by the leverage in the box, pendulum lever etc. In this case the efficiency of the nut is not affected so alarmingly by a change in μ, and that means that the efficiency when turning does not fall off a great deal, and yet joggles | ||