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).
Quarterly complaints regarding Phantom II pistons, suggesting an increase in piston length.
| Identifier | ExFiles\Box 15\3\ Scan052 | |
| Date | 5th January 1931 | |
| Hs{Lord Ernest Hives - Chair}✓ By Wor.{Arthur Wormald - General Works Manager} RECEIVED 19 JAN 1931 HS{Lord Ernest Hives - Chair} E.{Mr Elliott - Chief Engineer} Attached is a copy of a note from Mr Hx you would consider giving us more bearing area, how would you like us to test it? Mx{John H Maddocks - Chief Proving Officer}8/T5.1.31. PHANTOM II PISTON - QUARTERLY COMPLAINTS While we have considerably reduced the number of complaints due to piston trouble, and with the introduction of extra cylinder lubrication, we hope to reduce them still more - I consider that we can improve the Phantom piston by increasing its length. The first 50 Phantom II Chassis were much shorter on the bearing area than those fitted to Phantom I. As the result of experience on test these were increased in length by .4" with beneficial results. By comparison with the 20/25HP piston which gives no trouble on test and practically none in service with piston knocks, the Phantom II piston is still deficient in bearing area. The ratio of length to diameter is - Length. dia. 20/25HP. 3.250. 2.600 Phantom II. 4.250. 2.600 therefore the Phantom II piston should be .800 longer to put it on the same basis as the 20/25HP piston. This may mean an increase in piston weight of approximately 2 ozs. It is a matter for design and experimental work to go into. Incidentally RRAI. have always been in favour of a long piston, and use a piston .600 longer than our present standard, and they claim with beneficial results for absence of piston knocks and long life. [Illegible signature] | ||