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).
Technical discussion on Dunlop tyre safety, pressure gauges, and the use of security bolts.
| Identifier | ExFiles\Box 53\1\ Scan142 | |
| Date | 14th September 1923 | |
| BY5-F14.9.23. contd. - 4 - The Dunlop Co. are emphatic in stating that the only tyre which is safe from the point of view of it not being possible to force it off the rim, even when deflated, is the straight sided tyre, and therefore it would appear that we should do our utmost to persuade customers off any idea they may have at any time of fitting the old type beaded edge tyre. As a protection against the trouble occurring they can only recommend that a close watch should be kept upon the tyre pressures, a point being made of checking the tyre pressures regularly every day. For this purpose they have designed a reliable air pressure gauge, which is about the size of a small watch, only acting in one direction and in consequence is reliable to a maximum error of 5%, a degree of accuracy which none of the Schrader pressure gauges or any other type gauge on the market approaches. By making the gauge single acting so that after reading an indication it is returned to zero by a small lever, enables them to cut out the usual fragile mechanism common to pressure gauges of the bourdon tube type, whilst the special tangential fitting of the air pressure only and its attachment in this manner to the bourdon tube, enables a reliable tube to be produced which is exceedingly robust and free from localised weaknesses. The foregoing summarises the remarks covered and the discussion and EP. {G. Eric Platford - Chief Quality Engineer} and myself both feel convinced of the correctness of the attitude adopted by the Dunlop Co. in connection with the use of so called security bolts. We think the evidence put forward is sufficiently convincing to satisfy S. that the position adopted a year ago, in accepting the Dunlop Company's recommendations, after making confirmatory tests, was, and is fully justified. We think that to go back to the use of security bolts in the face of the Dunlop Co. recommendations will be entirely wrong, for that at the moment it might ease the situation, because immediately a failure occurs the conclusion is at once arrived at when security bolts are absent, that the absence of the bolts is the cause of the trouble. in 9 cases out of 10, the large burst in the tube which inevitably occurs is accepted as the cause of the tyre being deflated, whereas the Dunlop Company have incontestable evidence that in every case the trouble has been a slow leak, either from a faulty valve or a slight puncture, and the reason they contd. | ||