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).
Analysis of piston ring arrangements, dry wear tests, and conclusions on cylinder and ring materials.
| Identifier | ExFiles\Box 132\4\ scan0029 | |
| Date | 19th November 1936 guessed | |
| -3- Suggests that reason of slotted scraper ring may be due to attempt to obtain a quicker bedding ring. Best arrangement of rings seem to be (aero practice)- Two or three plain compression rings.) One or two slotted scraper rings. ) Above gudgeon pin. One bevelled ring at bottom of skirt. Dry wear tests. Dry wear tests seem to be promising in giving the most satisfactory results for predetermining cylinder wear. Best results obtained as follows:- Minimum cylinder wear occurred with Chromium-Molybdenum liners at 400 Brinell and rings at 410 Brinell. Next best Nitrided barrels at 1000 Vickers rings at 410 Brinell. Among the cylinder materials tried minimum ring wear occurred in all casts with 410 Brinell rings, the lowest ring wear occurred with nitrided materials followed closely by carburized S.A.E.2512 and Chromium-Molybdenum. Increased cylinder hardess seemed to produce slightly higher ring wear, but effect of ring hardness on cylinder wear apparently varies with cylinder hardness. In relatively hard barrels increase in ring hardness reduced cylinder wear but in soft barrels the hardest rings produced the greatest wear. Insley's conclusions. (1) Effective temporary expedients to produce satisfactory cylinder and ring behaviour are in use, but basic causes and general formula for preventing excessive cylinder wear and ring wear are still to be discovered. (2) Relatively soft plain cast Iron rings seem to be most successful. (3) Carbon steel and Chromium-Molybdenum cylinders can be used satisfactorily with conventional rings. (4) Hardness, especially, nitrided, cylinder barrels are now dependable and in general will shew definitely less wear than Carbon steel or Chromium-Molybdenum. continued. | ||