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).
Investigation into steering joggles on the Phantom III model.
| Identifier | ExFiles\Box 95\1\ scan0347 | |
| Date | 23th September 1936 | |
| Rs{Sir Henry Royce's Secretary}/PJH.14/RW.23.9.36. Phantom III Steering. We have recently completed a number of tests on the bumper drums to investigate steering joggles. The tests consisted of (a) a determination of the effect of varying flexibility in the steering system, (b) a comparison of the La{L. A. Archer} Salle gear with the standard Ph.III gear, and (c) a determination of the effect of varying front damper loads and of the addition of dry friction damping. Each bumper drum was fitted with two 0.750 high cams spaced 180° apart, the cams on one drum being 90° to those on the other drum. Measurements were taken of the amplitude of the joggle on the steering wheel, of the movement of the front end of the side steering tube, and of the vertical movement of the road wheels. During a preliminary run it was found that over a speed range from 0 to 70 M.P.H. surface speed on the drums there was bad joggling between 39 and 48 M.P.H., while at other speeds both the steering wheel and the road wheels were reasonably steady. Between 39 and 48 M.P.H., corresponding to impulse frequencies of 550-680 cycles/min., there was very violent wheel hop and correspondingly violent joggle. Varying the flexibility of the steering system varied the amount of joggle but did not alter the amplitude of the wheel hop or the speed range over which it occurred. For the tests under heading (a) above, a pendulum lever in the form of a hairpin with adjustable flexibility was used. The drums were run at the speed corresponding to maximum joggle, while the measurements were taken. The attached curve No.1 shows the effect of varying the flexibility. The flexibility is expressed as the torque required to twist both front wheels through 1° with the steering wheel fixed rigidly. | ||