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).
Comparison of the puncture resistance and cushioning effects of low-pressure versus normal tyres.
| Identifier | ExFiles\Box 53\2\ Scan041 | |
| Date | 21th August 1923 guessed | |
| 4. Reference to this Table shews that the "axle displacement" caused when using Low Pressure Tyres is normally 5/6 as much as when using normal tyres. 15. PUNCTURE RESISTANCE. Reduction in internal pressure combined with greatly increased flexibility makes Low Pressure Tyres much better able to resist punctures. It is obvious that if the tyre can give to - or 2" swallow" - the obstacle sufficiently, it will not be damaged or penetrated by it. Photo No. shews how a stone is swallowed. Photo No. (spikes loaded) how sharp spikes are resisted. Photo No. shews a normal tyre on a cross bar of ...... diameter. Photo No. shews a Low P.Tyre on a cross bar of ...... diameter. It is obvious that merely reducing the pressure and increasing the section will not make a tyre puncture proof - but in conjunction with a satisfactory tread and casing construction they guard effectually against all but very abnormal road obstacles. The Low pressure tyre is more "receptive" [strikethrough]xobstaclesx[/strikethrough] but much less easily "penetrated" by obstacles. 16. CUSHION EFFECT AT SPEED. Table No....... shews that under static loads the Low Pressure Tyre is ...... % more absorbent than normal tyres at normal pressures, but to give a reliable figure with a moving car requires the help of a seismograph or photographic records. In practice the increased cushioning of the Low Pressure principle can only be realized by actual experience on the road. The effect is to - a) Absorb small shocks which cannot be dealt with by springs at all at speed. b) Greatly reduce heavy shocks. c) Eliminate minor rattles and noises on the chassis making it possible to hear engine and transmission noises which normally would be drowned by body and wing etc noises. d) Shocks and vibrations on steering wheel are greatly reduced and only the major ones are felt on the hands. e) Maintenance charges are reduced as regards all spring or unsprung parts. f) Reduce wheel spin & thus increase efficiency with reduced petrol consumption on rough roads. | ||