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).
Material compatibility issues with steel sump and sludge plugs in aluminium and duralumin components.
| Identifier | ExFiles\Box 19\4\ Scan169 | |
| Date | 22th August 1930 | |
| x7772 E.{Mr Elliott - Chief Engineer} C. Sg.{Arthur F. Sidgreaves - MD} C. Wor.{Arthur Wormald - General Works Manager} c. Hs.{Lord Ernest Hives - Chair} RECEIVED AUG 23 1930 BY/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 22.8.30. Lec. 2788 L.H.P.11. SUMP DRAIN PLUG. EL/M.{Mr Moon / Mr Moore} 21.8.30. Lec. 2791 L.H.P.11. SLUDGE PLUG IN AUTO KLEAN FILTER. ------------------------------------------------ I am quite certain from our experience with the screwed piece in the Duralumin caps for the main bearings of the aero engines that we cannot possibly utilize a steel plug screwed direct into the aluminium, where such a plug has to be taken in and out, even on a comparatively few occasions. Even if the material were altered to bronze to overcome expansion difficulties to prevent the part working loose, we find that the thread increases in size even in duralumin caps, and I have had to arrange for inserts to be used on repair 'F' engines for quite a number of these parts. As pointed out in my previous memo BY1/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 20.8.30, immediately I saw that the insert was not locked we modified the design to lock it thoroughly, and we carried out a similar improvement with the sludge plug. With the experience that I have had with the aero engine, I am satisfied that we should have the plug seriously loose in the thread after a comparatively small number of removals. We are instructing what R.{Sir Henry Royce} wants experimentally, which I think is the only reasonable plan to adopt. We are aware that on a number of other chassis gun metal plugs are used direct in aluminium, but in all the cases I know of a leather washer is used, and the plug itself is sloppy, and this type of joint cannot be relied upon as remaining oil tight. BY.{R.W. Bailey - Chief Engineer} | ||