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).
Tests on high-speed steering wobbles by altering wheel and pivot pin configurations.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan278 | |
| Date | 8th December 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. ORIGINAL Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rnl/LG8.12.25 EXPERIMENTAL REPORT. HIGH SPEED STEERING WOBBLES. +657 X8430 To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} ✓ c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} ✓ c. to Wor.{Arthur Wormald - General Works Manager} ✓ We have carried out further tests to ascertain the effect of bringing the plane of the wheel in proximity to the plane of the pivot pin. In order to do this we arranged special hubs to take Michelin disc wheels, and obtained special disc wheels to take balloon tyres so that we could obtain wobbles without resorting to out of balance (see attached sketch). These wheels necessitated new steering arms, but the alteration necessary only affected the steering on considerable locks quite outside the range of a normal wobble. With the present pivots we were able to bring the plane of the wheel within 1.00" of that of the pivot pin. This gave a tyre contact 1.597" inside centre point (see sketch). The tests were carried out with 6.75" balloon tyres at 20 lbs/sq.in. inflation pressure. The pivots were fitted up to N.Sch.1896. No front shock absorbers were fitted. We found that with the wheels fitted up in the normal manner (i.e. dished in) and carefully balanced we could obtain violent wobbles from 45 m.p.h. upwards. We could not drive through the wobbles. These wobbles were quite as bad as we should expect to get with standard arrangement of wheel and pivot. We then reversed the wheels so that they were dished out. This made the plane of the wheel about 5.7" from the plane of the contd :- | ||