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 geometry issues, specifically the 'joggles' and 'twitching' in the 20 HP model compared to the 40/50 HP.
| Identifier | WestWitteringFiles\Q\February1927-March1927\ 5 | |
| Date | 1st February 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Ra. c. to SJ/ Wor.{Arthur Wormald - General Works Manager} 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 OY. ORIGINAL Hs{Lord Ernest Hives - Chair}/RWS/LGL. 2. 27. STEERING GEOMETRY. X8430 X5430 We have been carrying out investigations to ascertain why the 20 HP. is on the whole worse for joggles than the 40/50 HP., even when both are fitted with comparable flexibility in the side steering tube. The 'twitching' of the 20 HP. wheel is particularly noticeable when running over transverse ruts or obstacles at moderate speeds. We have taken some practical tests which show that the movement of the axle on the 20 HP. affects the steering wheel in a very much greater degree than on the 40/50. Normally the axle movement is so small that the springs absorb the side steering tube displacement without throwing much load on the drivers hand. Owner driver's objections, however, are not that they cannot hold the steering wheel still, but that when they hold it lightly it 'nibbles' at their hands. Calculated figures do not agree very closely with those obtained practically but clearly confirm the fact that the 20 HP. may be expected to suffer from 'joggles' very much more than the 40/50. The displacement imparted to the side steering tube by the axle movement is so considerable on the present outside pendulum lever that in the extreme case the whole of the side steering tube spring movement is absorbed and the contd :- | ||