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).
Analysis of a damaged Dunlop Jack, identifying over-winding as the cause and proposing modifications.
| Identifier | ExFiles\Box 48\1\ Scan029 | |
| Date | 9th June 1927 | |
| Hs. {Lord Ernest Hives - Chair} X.4124 BY1/H. 9.6.27. W.P.S. W.B.G. DUNLOP JACK. ------------ The Dunlop Jack which was damaged by Sales has been carefully examined by Mr.Carr of the Dunlop Company, who reports that the whole cause of the trouble was not that the jack had failed in lifting the load, but that the first-intention screw for obtaining the correct setting for the axle height initially had not been used, and that the jack had been, in consequence, over-wound. Of course it would be possible, even if the first-intention screw was used, if the jack was forced beyond its limit, to burst the jack. This is precisely what happened in the case under discussion. The Dunlop Company have decided to make certain modifications so as to make the jack less susceptible to fracture by over-winding, but their view of the matter is that it will be extremely difficult and prohibitive from a cost and weight point of view, to add such sections of material as to arrive at this end absolutely. They are proposing to send us a jack modified to meet these require-ments in the near future, and they propose to cast on the jack the following words:- "CAUTION - DO NOT OVER-WIND". They conclude by saying they are convinced that the alterations they are making, plus the novel features of the jack, will make the most satisfactory article in existence for our particular needs. DERBY ROLLS-ROYCE LIMITED | ||