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).
Engine test failure, detailing power observations and the subsequent examination of seized and damaged components.
| Identifier | ExFiles\Box 179\2\ img107 | |
| Date | 11th December 1931 | |
| -4- at 90% load was run off satisfactorily - (the auxiliary oil pressure was 4 lbs/sq.in.) - but after one minute at 2800 R.P.M. the header joint blew out at the rear end of B. bank. The joint was remade with three thicknesses of vellumoid and heldite and a further attempt made. On the 15 mins at 90% load the magneto setting for maximum power was found to be 22º B.T.D.C., the tolerance being 25.5º - 17º B.T.D.C. The engine was then opened out to F.T. at 2800 R.P.M. The power at the start of the 5 mins. observation was :- 610 (actual) BHP. or 632 c/BHP. at a cons. of .485 pts/hp/hr. Mag. setting for maximum power. 20.5º B.T.D.C. Tolerance on setting. 22º - 19º B.T.D.C. After the first 2 - 3 minutes running the lift began to fall off gradually and steadily and at the end of the 5 mins. period the power was 565 B.H.P.(actual). The breather and reduction gear housing was smoking badly and a noise similar to very heavy detonation became evident shortly before shutting down. There were, however, no sudden fluctuations in lift. The engine was shut down and on removing the oil filters, large pieces of aluminium were found in the scavenge filter. The engine was therefore returned to the shop for inspection. Results of Examination. It was found that A.6 piston had seized. One gudgeon pin boss was completely broken away and the gudgeon pin had pieces of aluminium welded all over it. The little end bush had also seized on the gudgeon pin but was free in the rod. The connecting rod was "blued up" at the little end. A.6. piston was burnt on the top land at the side nearest the inlet ports. All the other pistons appeared normal and showed no signs of overheating, the piston and head rings were all free. All the knuckle balls on the sleeve drive were satisfactory with the exception of A.6. on which the white metal had run due to the overloading caused by the piston seizure. (Photographs of the head and piston from A.6. cylinder are attached.) Reduction Gear. The gears were showing signs of plucking at the top and bottom of the teeth. The oil pressure was increased prior to the start of the tests from 2.5 to 4 lbs/sq.in., but although | ||