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 to a supplier regarding faults found in a jacking system and suggestions for improvement.
| Identifier | ExFiles\Box 140\2\ scan0178 | |
| Date | 31th March 1939 | |
| 1166 Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}1/MH.{M. Huckerby} 31st. March, 1939. Messrs. Smith's Jacking Systems Ltd., Edgware Road, Cricklewood, LONDON, N.W.2. For the attention of D.W.Sessions, Esq. Dear Sirs, Thank you for your letter of March 29th. Since receiving this we have again dismantled the jack, this time removing the ram tube also. We find that there is a small taper spring under the replenishment valve, but that this does not exert any appreciable force when the ball is on its seat. This seat will not hold liquid even when the ball is held down with considerable force. We make the following observations. It is very likely when screwing the ram tube into the zinc casting that particles of thread will get into the jack. It appears that the valve seats are part of a pressed-in steel tube. We have always found on shock dampers that a ball valve must seat on a hard knife edge and not on a spherical or taper seat. The replenishment valve requires a stronger spring. A gauge filter on top of the ram tube might prevent a lot of trouble by preventing particles of thread getting into the valve chamber. Theoretically we agree with you that air cannot get into the jack, but in practice this is not always the case. We therefore do think the filler plug should be in the top of the cover. We will send you back the jack we have as soon as we receive some of the six we have just ordered, or immediately if you can send us a jack to replace the faulty one and onto which we will transfer the forked bracket. | ||