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).
Letter detailing engine oil analysis and the performance of new piston and ring sets in vehicles.
| Identifier | ExFiles\Box 32\3\ Scan049 | |
| Date | 26th October 1920 guessed | |
| -2- The oil used with all these vehicles is Willcox P.1. Motor Oil and I have today taken a sample from the crankcase of the above engine and although it has naturally deteriorated somewhat in "brilliancy" its "viscosity" appears to be very little impaired. Under these circumstances I am led to hope that this oil will suffice for another month's running without risk of serious deterioration, and this result, coupled with a system of oil purification I have under consideration, I anticipate being able to use oil over and over again with the addition of a small percentage of fresh oil if necessary in order to maintain sufficient viscosity. A new B.T. type "Thornycroft" vehicle has also been fitted with these pistons and has been in constant use since the 26th ult. up to date without further oil being added to the crank case. The first set of pistons had one only "Allen" Patent segmental gapless ring fitted to each piston, while those fitted to both "Thornycroft" vehicles had two of these rings, each one being fitted respectively as near the "Head" and "Skirt" as possible. The rings on all three sets of pistons were similar in as much as they presented one sixteenth of an inch only contact surface to the cylinder wall, which, compared with that of the ordinary piston with "one cut" "Ramsbottom" rings, viz: 3 or 4 rings per piston with a quarter to five sixteenths of an inch contact surface to each, would obviously account for a considerable reduction in frictional losses and consequent increase of power. It was not my intention to unduly encroach on your valuable space by attempting to explain the technical details of this piston, that of course is the province of the Patentees and Manufacturers, Messrs. Allen & Simmonds Ltd. of Reading, but merely to put before your readers the actual results of my personal experience with same, and, needless to say, orders have now been placed for all vehicles under my control to be fitted with these pistons as early as possible. Very similar results have been obtained by other users, notably the Reading Corporation, the first Bus fitted having completed 6,500 miles on the consumption of five quarts only, of oil, as compared with one gallon per 100 miles with the standard pistons. In conclusion, I venture to think Mr. Smith will agree that I have put up a very good case in support of my plea to differ from him, by submitting to the consideration of all keen business men who are interested in the conversation of lubrication oils, to say nothing of fuel consumption, indisputable facts concerning a "Prime Mover" Component, which, in my humble opinion, will go far towards accomplishing that very desirable object. Yours faithfully, )(signed)( Victor B. Butt. A.M.I.Mech.E. | ||