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).
Testing S/M nuts as a substitute for S/S nuts for the Phantom III carburetter drain pipe unions.
| Identifier | ExFiles\Box 159\6\ scan0024 | |
| Date | 24th August 1937 | |
| from HPS{Horace Percy Smith - Experimental Factory Mgr}/W. Bell. c. to Rm.{William Robotham - Chief Engineer} 1371 HPS{Horace Percy Smith - Experimental Factory Mgr}/WB.{Mr Brazier/Mr Bell}1/CB.24.8.37. PHANTOM III DRAIN PIPE UNION NUTS. E.88038 S/S and S/M and Ex.28686 S/M Nuts. To prove that S/M nuts could be substituted for the S/S nuts at present standard on the carburetter drain pipe unions, one off each material produced to E.88038 were tested on an E.88031/40 union and E.76000 nipple. In conjunction with these two types, a third model to Ex.28686, having a 100% longer hexagon was tested. Each type was first tested by tightening up normally and releasing six times as on an engine, using a standard 7/16" jaw spanner, and each type functioned satisfactorily. When however, extra leverage was applied (i.e. by attaching an extension one foot in length to the spanner) both the S/M and S/S E.88038 nuts were badly damaged. The corners of the hexagon were damaged, the bore was badly distorted, and threads tightened on to the union. Also the nipple end of the nuts was convexed and the parallel section (where the hexagon was relieved) had spread outwards. The Ex.28686 type was also convexed at the nipple end but showed practically no damage on the hexagon corners, neither were the threads as tight nor the bore as distorted as with the other types. Incidentally, after repeated tightening of the nuts, the nipples were opened out and could not be removed. Therefore, providing they are protected from corrosion, there is no reason why these nuts should not be produced in S/M to E.88038 drawing. The increased length of hexagon is recommended, to prevent damage to the corners (even though the added stiffness thus obtained is not considered necessary in this case) in view of the inaccessible position of this particular union nut. HPS{Horace Percy Smith - Experimental Factory Mgr}/W. Bell. | ||