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).
The investigation of high-speed wobbles, particularly the unexpected effect of shock damper loading on out-of-balance tyres.
| Identifier | ExFiles\Box 29\1\ Scan309 | |
| Date | 14th June 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to BJ. 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. X457 Hs{Lord Ernest Hives - Chair}/Rml/LG14.6.27. HIGH SPEED WOBBLES. X235 74214 It has been a source of surprise to us that beyond a certain point, increasing the load on the front shock absorbers will not prevent the most violent high speed wobbles. By this we mean that if we purposely take 7.3" four-ply tyres and put them a considerable amount out-of-balance, we have a condition where no amount of front shock damper loading will prevent the wobble building up, in fact beyond a certain limit of loading the wobble actually gets more violent as we increase the shock damper load. This is quite an exceptional condition which is never likely to occur with 6.75" tyres, but we have been studying it with a view to obtaining further information on high speed wobbles in general. We have conducted the tests on the bumper, running the front wheels on smooth drums as previously. Initially we experimented with various weights for the engine on the front of the chassis. The shock dampers were set with loads of 150 lbs. up and down. When a wobble was in progress the ends of the shock damper arms moved only about 1" or so and the front of the frame twisted. There appeared to be a node in the centre of the chassis about the driving seat, and the rear of the chassis upon which the ballast box was fixed vibrated with the same periodicity as the front (in the manner of two flywheels coupled by a flexible shaft). contd :- | ||