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 condition after testing and a summary of the advantages and future plans for Aerolite pistons.
| Identifier | ExFiles\Box 86\2\ scan0187 | |
| Date | 28th April 1934 | |
| -2- On dismantling it was found that all the rings and grooves were in excellent condition. The five pistons which had received the severe bench test work had distorted slightly, this being bad enough on two to cause the cold tap mentioned. Wear, however, on both the pistons and bores, appeared to be negligible. Lest it should be thought that the standard piston is free from knocks when run under the same strenuous conditions, we have a 20/25 which did the last two 10,000 miles on the road and two of the split skirt pistons on this have a knock which persists at all temperatures. Similar pistons in the hands of the customer, our Repair Dept. tell us, are seldom audible at 50,000 miles. Summarising. (1) The Aerolite piston has very definite advantages. (2) Mechanically it is entirely reliable. (3) Tests so far have shewn that it is not likely to be worse for knocks than our present split skirt type and that it gives satisfactory and consistent oil consumptions. (4) We believe we can improve the pistons further by altering the grinding form. Having done this, they should run in France on the next Bentley to get final confirmatory results. In the meantime, two sets will probably have run 20,000 miles each in England under normal driving conditions. (5) If we ultimately standardise these pistons on the Bentley, we can get experience in customers' hands which will tell us whether they have any disadvantages from the Rolls-Royce Owner's point of view. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||