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).
Mechanical failures during testing, specifically concerning cylinder head collapse and exhaust valve issues.
| Identifier | ExFiles\Box 134\1\ scan0058 | |
| Date | 13th December 1937 | |
| -7- Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards}9/AF.13.12.37 V.{VIENNA} EXHAUST VALVE LIFT cont'd Whilst it is appreciated that the tendency for valve bounce to occur as the valve seats, is aggravated, it is not thought that this would set in as as low a speed as 3000 r.p.m. where the falling off begins to get serious, and it does not seem as if a lift as low as .312 will be practicable even when used in conjunction with a larger valve. Further tests are, however, to be carried out. VI. MECHANICAL FAILURES During these tests, two serious troubles were experienced as under:- (1) CYLINDER HEAD FACE COLLAPSING - When this head was first fitted, the compression ratio was found to be too low, and .100" was machined off the face to bring the C.R. up to 6.3. After a short period of running, however, a severe water leak occurred from the water hole next to the inlet valve, on the centre line of the combustion space, and it was found that the head had collapsed .015" at this point. This error was rectified, but soon occurred again. The cause is put down to lack of metal at the point in question due to machining, and should be noted in the main engine design. (2) EXHAUST VALVES AND SEATS - Great difficulty has been experienced in maintaining the gas tightness of the exhaust valve, due presumably to valve distortion (1.600" diam.) and one valve has cracked across the face after 140 hours running. It is not thought that this trouble will be experienced on the 1.500" valve as over 300 hours were run on valves of this size without trouble. Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards} | ||