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).
History of the development and patenting of the 'T' slotted aluminium piston to address cold knocking issues.
| Identifier | ExFiles\Box 147\4\ scan0184 | |
| Date | 28th April 1942 | |
| To Rm.{William Robotham - Chief Engineer} 1247 By.5/EP.{G. Eric Platford - Chief Quality Engineer}28.4.42. Re: 'T' Slotted Aluminium Pistons. The history of the piston is that up till the war we used Cast Iron pistons, following the war Aluminium pistons were introduced and for two or three months only, engines were delivered fitted with pistons which had unslotted skirts, in other words, Aluminium pistons were similar to the Cast Iron pistons so far as being continuous of the skirt. The result of this was that starting up cold customers complained of piston knocks, R.{Sir Henry Royce} appreciated that this would happen but insisted that it was for only a short period of running immediately after starting up that knocking occurred. CJ. however refused to agree and wished to go back to the Cast Iron piston, this R.{Sir Henry Royce} absolutely refused to do, pointing out that there was obviously another way out of the trouble than going back to the known faults of the Cast Iron piston. As the result of considerable amount of experimental work done in the course of two or three months we adopted the 'T' slot on piston E.18125.A., the drawing in question was issued to the works on 21.11.1919 and was incorporated on the piston part list about the same time. Anyway having produced this design and demonstrated that it overcame the cold knocks we replaced all Aluminium pistons which had been issued following the war, This was done in early 1919 and 1920. The only documents we have would be prints from our part list and the print of the piston showing the dates at which the part list and the piston were instructed. This information should be sufficient for Chryslers purpose, in the meantime I am making enquiries as I have an idea that we took out a patent for the 'T' slot. By.{R.W. Bailey - Chief Engineer} [Signature] P.S. This type of piston was patented in November 1919, Pat. No.140988, taken out in Hs.{Lord Ernest Hives - Chair} name, E.W. Hives. Having stated the above point I think all that is necessary is the patent number which represents publication, also the further fact that we used these pistons from 1919 and early 1920 exclusively is further evidence of publication. [Handwritten note in left margin]: By (By Telephone). [Handwritten note at bottom]: All engines delivered to the U.S.A. 1920 onwards had the split skirt piston, & R-R Inc incorporated such a piston on their productions EJ. 30/4/42 | ||