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 discussing the history, issues, and design changes related to the lubrication of the clutch spigot.
| Identifier | ExFiles\Box 20\1\ Scan033 | |
| Date | 27th February 1928 | |
| Copy X872 Oy3-W-2272S February 27, 1928. PERSONAL Mr. E.{Mr Elliott - Chief Engineer} Platford, Rolls-Royce, Limited, Derby, England. Dear Mr. Platford: Re Lubrication of Clutch Spigot Replying to yours of February 1, the position of this at the time of its adoption was that because of leakage of the oil valve which had developed on the road and had to be rectified in emergency, fully fifty per cent of the cars, pre-war, post-war, imported, and American, had had the oil valve definitely canceled by removing or sliding back the operating pin. Some of these cars had run upwards of 25,000 miles in this condition, and in no case had a clutch spigot been encountered which had shown dry or squeaked, due to this change. A single case had occurred on test where the spigot had half-seized and caused a dragging clutch, when the oil-valve was operating, and this had been traced to too close a fit between bush and spigot. The limits had therefore been revised to 1.000+1 for the bush and .997-1 for the spigot, giving a definite 3 to 5 thou. slack. Since then, no case of seizure has occurred. Before omitting the oil valve, a clutch was assembled entirely without oil in the bush or spigot and run for fifteen minutes continuous at 1500 revolutions. On dismantling, there were no signs of seizure, and oil from the clutch had already moistened the spigot. Since then, 125 cars have been made without the oil valve and no trouble has been encountered. On dismantling, the spigot and thrust bearing have always shown adequate lubrication. These, of course, are assembled with initial lubrication of the spigot. | ||