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).
Comparing the performance of the Marles Weller R.R. Elliott type steering system against a standard system.
| Identifier | ExFiles\Box 28\2\ Scan155 | |
| Date | 20th March 1933 | |
| xU.94 To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}1/MJ.20.3.33. MARLES WELLER R.R. ELLIOTT TYPE STEERING. There are one or two points in connection with the Marles-Weller steering gear which we think we may not have made clear to you since we have never officially reported upon the way in which the results on Sg{Arthur F. Sidgreaves - MD}'s car were obtained. In the first place we would say that we consider Sg{Arthur F. Sidgreaves - MD}'s car to be perfectly satisfactory from the point of view of road shocks. On the other hand the self-centering was slightly more sluggish than that of our own cars. The lightness was very satisfactory, being equal to a good R.R. steering. In obtaining these results, however, the gear ratio of the steering was considerably lower than our standard ratio, actually as 17¼ - 1 is to 13 - 1, the main reason for this is that the Marles Weller type of gear is not as efficient in a forward direction as the R.R. We attach herewith a print which will show you that Marles Weller is about 50% and a good R.R. steering is nearer 75%. We do not suffer on the road from the low gear ratio because we get back the selectivity by being able to remove the side steering tube springs. The next point was the self-centering. Since the Marles Weller is much more irreversible than the R.R. we should expect the self-centering to be a little more sluggish. Actually the helix angle was 10¼° which the makers consider is about the lowest helix angle which should be utilised to get normal self-centering. We therefore feel that the temporary scheme you have sent through utilising the R.R. will not selfcentre at all with a helix angle of 7° 10´ We have tried another Marles Weller steering with a helix angle of 11° and the irreversibility under road shocks seems quite satisfactory whilst the self-centering is definitely improved. The over-all box ratio of the steering on Sg{Arthur F. Sidgreaves - MD}'s car is 17¼/1 in the central position and therefore in order to get this low ratio with such a high helix angle the rocking arm in the box is considerably longer than ours. We used a standard pendulum lever (7.750" long) to get the best results with this 17¼/1 over-all ratio. The box ratio on the standard R.R. which will also be on your Marles Weller is only 13/1. | ||