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).
Piston failure and scraper rings, proposing modifications to reduce stress.
| Identifier | Morton\M3.2\ img018 | |
| Date | 16th March 1925 | |
| TO HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} ORIGINAL SECRET. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. R1/M16.3. 25. PISTON FAILURE & SCRAPER RINGS. X8040 This is quite a reasonable failure due to high engine speeds and ~~explosions causing~~ concentrated alternating stresses at the end of the horizontal saw cut. How can these stresses be reduced? My first idea was to drill a hole to finish the saw cut, then reinforce round the hole. Another way to use two 1/4" fine thread bolts to reinforce the aluminium. These might bind into the piston pin at one or both ends. They could be used as a means of making the piston pin tight, but I should not recommend slotting (splitting) the boss. Do we still use the diagonal webs? One thinks that we ought. My impression is that the aluminium is OK. for compression due to the stresses caused by the explosions, but following these by the tension at high speeds at the end of the exhaust stroke is too much for the metal, and either the section of the metal is different in the die castings. It would seem that some definite improvement should be made and the engine should be fitted with suitable (1) | ||