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).
Analysis of low-speed wobble caused by issues with cross steering tub joints.
| Identifier | ExFiles\Box 95\1\ scan0407 | |
| Date | 19th May 1937 | |
| To E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. Hs.{Lord Ernest Hives - Chair} c. Sy. c. Ol. c. Ev.{Ivan Evernden - coachwork} c. RBC. c. Ex. c. Hd.{Mr Hayward/Mr Huddy} c. Km/GwH.{George W. Hancock - Head Chateauroux} 35-0 Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer}1/AP.19.5.37 PH.III. CROSS STEERING TUB JOINTS. Cases of low speed wobble have occurred on customers' cars and on 35-EX. in France, due to the friction of the cross steering ball joints failing in service:- Possible causes of this are:- 1. Either of the ball pads turning in the housing. 2. Spring rating too high resulting in loss of spring load if wear occurs. 3. Reduction of the coefficient of friction between the ball and the pad, as the surfaces become run in. (1) The lower ball pad G.83415 is made a tight press fit in the housing. Production improved their method of fitting these after chassis 150 in B. series. Some cases of loose pads may occur on chassis before this and a Depot Sheet has been issued instructing that they should be sweated in. In the case of the upper pad G.84934, the split type of pad was fitted at approximately the beginning of B. series, and is used for replacements. This type of pad has now completed mileages of 5000 - 10,000 on all experimental cars and 25,000 miles in France on 35-EX. satisfactorily. It was reported from France that the pads on 35-EX. were turning but subsequent investigation at Derby did not confirm this. The only other case in which turning of these pads has been reported was at the Paris Depot. The parts are not now available so this report cannot be confirmed. In view of the above we do not consider that any design alteration on the pads is yet justified. (2) The rating of the springs G.83416/7 is quite reasonable and as the wear is negligable this cannot be the cause of the loss of friction. The present springs are, however, unsatisfactory for the reason mentioned below. continued | ||