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. regarding issues with security bolts on cord tyres.
| Identifier | ExFiles\Box 171\3\ img129 | |
| Date | 26th July 1922 | |
| Dunlop Rubber Co., Fort Dunlop, Erdington, Birmingham. 26th. July 1922. dicated 25th. Service Manager, WB.{Mr Brazier/Mr Bell}GG.24.267. Messrs. Rolls-Royce Ltd., Nightingale Rd., Derby. Dear Sirs, For the attention of Mr. Harvey Bailey. We are now confirming the writers conversation with you on the subject of security bolts and valve plates. As informed you, occasional complaints are received from Rolls-Royce owners of cord covers blowing off the rim, and as we know that the cause of such occurrences can only be due to a loss of inflation pressure allowing, at some critical stage, the bead to lose its hold in the clinch of the rim, we have found that this is caused by the use of the conventional type of security bolts. The beads of the cord tyres being necessarily large and of a different design from these of Canvas tyres, do not allow the ordinary security bolt to come down into place. As a result of this the inflated tube is forced in the space which is left underneath the bolt, and the severe local stretching of the tube over the sharp edge does actually in some cases cause a minute abrasion, or puncture, which quite unknown to the user, reduces his inflation pressure, and by permitting the bead to move, allows the tube to get underneath it and force the bead over the rim. In all cases, we may say they are not peculiar to Rolls-Royce cars, where we have removed these security bolts the trouble has disappeared, but as far as the Rolls-Royce vehicles are concerned, we find we are up against a definite recommendation from you that security bolts must be used. We, therefore, thought it necessary to put before the position, with a view to satisfying you that the circumstances in connection with cord tyres having changed, no good purpose is now served by insisting upon the use of security bolts. The official recommendation of the Dunlop Co., for which we are prepared to take the fullest responsibility, are contd:- | ||