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).
The difficulty in locking unions on Phantom III castings and the remedy of including a specific spanner in the kit.
| Identifier | ExFiles\Box 130\2\ scan0368 | |
| Date | 23th December 1936 | |
| RM.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/GWH{George W. Hancock - Head Chateauroux} c. BY/HEB{H. Biraben} c. BY/CS 1113 BY.1/G.23.12.36. PHANTOM III. -------------- Referring to Rm.{William Robotham - Chief Engineer}7/JH.24.11.36. which I overlooked replying to earlier, although the investigation was started out at the time the memo was received, the position is that it was not possible to lock unions which are screwed in-to the body of the casting. This has been tried in a number of ways, but has always failed due to the fact that the effort in tightening up and undoing the nut of the union always results in a slight movement of the piece in the casting. The union is fitted with a positive interference fit of .002" on the mean pitch diameter of the thread, and unless excessive force is used in tightening up the union nut the fitting in the case should remain tight. We note, however, a number of them will screw out owing to the effort with which the union has been screwed up originally, and our only remedy is to use a spanner on the hexagon fitted to the piece which is screwed into the casing. I will see that this spanner is included in the kit. BY.{R.W. Bailey - Chief Engineer} By | ||