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).
Letter from Dunlop Rubber Co. Ltd. regarding tyre security bolt tests and recommendations.
| Identifier | WestWitteringFiles\I\July1922\ Scan114 | |
| Date | 26th July 1922 guessed | |
| contd:- -2- which we are prepared to take the fullest responsibility, are contained on pages 23 and 24 of the enclosed booklet "Dunlop Tyres 1921/22", and also on page 15 of the booklet - "The care of Tyres" enclosed herewith. In addition we have undertaken a series of tests on the test Rolls-Royce car which we previously owned, and have quite satisfied ourselves that creeping or blowing off does not take place until the tyre pressure has fallen dangerously low, say to the order of 10/20 lbs. per sq.in. In this case, while we actually failed in test to get the tyres to blow off, we did get them to creep considerably, and the presence of security bolts or bolt valve plates made no difference whatever to the extent of the movement, or to the damage which was done to the tube. As a matter of fact with the security bolts the cover was considerably damaged due to the delay in the movement of the cover at the points where the security bolts were fixed. We, therefore, make the definite recommendation to you that in present circumstances you should withdraw your stipulation for the use of security bolts with cord tyres, and we trust you will be able to agree with this. We understand you have been advised from France that some of your people have come to a similar conclusion as to the damage which is caused by security bolts, and that one of our chief competitors is also making a similar recommendation. Of course, the objection to the ordinary ^type of security bolt could be removed by means of a special bolt designed for cord tyres, but whatever precaution may be taken with regard to the original equipment, it cannot be ensured that replacements would be correct. Further, the bolt designed for cord tyres would have a very bad effect when used with canvas tyres, and that would certainly be worse than no security bolts at all. We, therefore, sincerely trust that in the interest of all concerned you can accept our recommendation, and we shall greatly appreciate it if you will advise us your official attitude at your early convenience. Yours faithfully, FOR THE DUNLOP RUBBER CO.LTD., (sgd.) W.Bond. | ||