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 discussing the placement of security bolts for wheel balancing.
| Identifier | ExFiles\Box 4\3\ 03-page27 | |
| Date | 4th July 1912 | |
| L. F.{Mr Friese} Gjers Esq., -3- July 4th.1912. in overcoming your difficulties by disposing the security bolts in such a way that they would balance to some extent the weight of the valve, but we do not think this practice is really correct on theoretical grounds, because it is of some importance that these bolts should be disposed at equal distances round the felloe, in order that they may perform their primary duty satisfactorily, which is to retain the bead in the clinch. If however the bolts and valve are together disposed in such a way as to be in balance, then you will find that you are inadvertently expecting the valve to act as a security bolt, or at least that the distance between the two bolts on either side of the valve is greater than can be considered safe. Our present practice is to dispose the security bolts at equal distances round the rim (the valve is not equidistant between the adjacent bolts owing to the relation between the number of spokes and bolts) and to balance the wheel with these, together with the valve, in place, but without the inner tube or outer cover. This gives us the correct balance excepting for the lap joint in the inner tube and irregularities in the inner tube and cover. We do not see our way to carry the matter any further with any degree of satisfaction until the tyre companies can be persuaded a more uniform system of manufacture. | ||