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 wobbles, friction, and the effect of wheel dishing.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan279 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Sel/LCR.12.25 pivot pin, and the tyre contact about 3" outside centre point. Under these circumstances we could obtain no shimmy at any speed. The steering was definitely heavier with the wheels dished out, so we carried out a test to determine if the increased friction in the pivots due to the large moment of the weight about the king pin was responsible for eliminating the wobbles. We did this by placing the wheels on the axle dished in, and using Hartford shock absorbers on the cross steering tube, increased the friction in the steering system until we eliminated wobbles. We then measured the steering effort required by means of a set-up spring in the side steering tube. Having removed all friction, we reversed the wheels and repeated the test. The results showed that for normal locks the steering was equally heavy in both cases. For very slight deviations from the straight, however, the dished out wheels without added friction gave a 25% lighter steering with greater selectiveness. We should therefore say as a result of these tests that bringing the plane of the wheel close to the plane of the king pin is bad for wobbles because it reduces the friction in the pivots bearings, and conversely. We expected the steering to be heavy on locks with the wheels dished out because under these conditions, owing to the large pivot pin inclination (~) the car has to be lifted an appreciable amount unless the plane of the king pin is close to that of the wheel. We are repeating these tests with the vertical pivot axle when this becomes available. The condition of the roads lately has caused consider- able delay in carrying out expl. tests on steering wobbles. HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||