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).
Demountable straight-sided rims coming off when tyres deflate and the subsequent fix developed with Dunlop.
| Identifier | ExFiles\Box 45\1\ Scan295 | |
| Date | 30th September 1922 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} X4050 RES/LG30.9.22. STRAIGHT SIDED RIMS AND TYRES. X4050 There has been one or two cases in which when a straight-sided tyre has become deflated that the demountable rim has come off and been lost. We have taken this matter up with the Dunlop people and they have now been able to satisfy us by showing us a rim that could be revolved at 70 m.p.h. with a flat tyre and not come off. With the Dunlop straight-sided rim the demountable ring must form a spring in order to prevent its opening out at high speeds with a flat tyre. On the early wheels we were supplied with, the demountable rings were not made of sufficiently good material to form a spring and after they had been put on, once or twice, the ring would take a permanent set so that it would fall on and was only kept on by pressure in the tyre. An easy test to see whether the rims are safe is to take off a demountable ring and when it is off the wheel the joint of the ring should overlap to the extent of 1/2 or 1/4". The overlap has to be kept a reasonable amount or else it increases the difficulty of changing the rim. The Dunlop Co. now however are supplying with each set of wheels a special tool so that the demountable rim can be easily handled. Hs.{Lord Ernest Hives - Chair} | ||