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).
Proposed modifications to pistons based on blueprint drawings Lec. 2029 and 2030.
| Identifier | Morton\M3.2\ img022 | |
| Date | 1st March 1925 | |
| TO - R.{Sir Henry Royce} FROM E.{Mr Elliott - Chief Engineer} (Handwritten: MAST MAJOR? я) Copy to - CJ. (Handwritten: (2401 of Mast Shad?) E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C.) Copy to - HS.{Lord Ernest Hives - Chair} (Handwritten: (4 WAHS?) (8?)) (Handwritten below HS{Lord Ernest Hives - Chair} line and crossed out: SECRET) (Handwritten above PISTONS: FUTURE PISTON & 6 VEE TYPES SECRET. (Copy to C.R. SHREWSBURY)) PISTONS. Please find attached blue prints of drawings Lec. 2029. and 2030., showing the modifications to the piston. These drawings have been sent to Derby. The 1st. one shows the reinforced piston as per your memo. and the 2nd. one shows the other modifications proposed for increasing the strength of the section across the saw cut. The policy we had been following was to strengthen up the die casting generally and make it follow the proportions of the sand casting. We had the idea of using a large hole for the saw cut to finish in and surrounding it with a boss, but we were loath to add any masses which might create spongy metal in the casting. The idea of spreading the webs did not occur to us until yesterday morning before DA.{Bernard Day - Chassis Design} brought over your telegram containing the same suggestion. Lec. 2030. shows the following proposed modifications:- (1) Webs spread out and those near saw cut increased in thickness as you suggest. (2) Holes for saw cut near webs made large as you suggest. (3) Holes for saw cut near webs made parallel to piston pin and bossed to avoid weak knife edge section at root of spring portion of piston. (4) Walls filled in immediately over piston pin bosses to provide thicker section near maximum stress. (5) Length of piston skirt increased by .5" at HS.{Lord Ernest Hives - Chair} request. This last item is asked for on account of a certain amount of trouble being experienced on the engine with piston knocks. If we have the ½" on the casting, it is there if required, and HS.{Lord Ernest Hives - Chair} will in the meantime determine if it is necessary. E.{Mr Elliott - Chief Engineer} | ||