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).
The causes and solutions for relief valve chatter on the Spectre model.
| Identifier | ExFiles\Box 96\2\ scan0062 | |
| Date | 26th September 1935 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} 4354 Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}25/KW.26.9.35. Relief valve Chatter on SpectreCodename for Phantom III. This trouble has been experienced on both the original relief valve layout (Lec.3790) using the small pump, and on the latest relief valve layout (Lec.4385) in conjunction with the large pump (Lec.4400). Our tests have been confined to the former system and show that the chatter is not confined to any one particular valve and can be a combination of, or any of the following valves: main pressure, low pressure, and the Tecalemit by-pass valve. The chatter we have found is never from the oil cooler by-pass valve, which only opens when starting cold and the pressure exceeds 60 lbs/sq.in. This by-pass valve is deleted on the latest layout as per SpectreCodename for Phantom III No.10 unit. The actual noise is the ball upon the seat at the point of opening, low and high rating springs with the same seat loading having been tried without any appreciable effect upon the chatter, either in speed or its intensity. Several attempts were made in the form of capacity chambers and damping the springs, the results of which were either inconsistent or not a mechanical job. Finally, a damper type of valve was used in every unit, these have been tried in, the chatter has been cured, these being used in all the three valves previously mentioned. The valves Hs.{Lord Ernest Hives - Chair}2035 are common to all, the caps for the low pressure and the Tecalemit by-pass are the same, to Hs.{Lord Ernest Hives - Chair}2036, and the main pressure cap to Hs.{Lord Ernest Hives - Chair}2038. The valves have a spherical end with a plunger extension and having a diametrical clearance of .012 - .014 on its guide, the latter being integral with the cap. With this clearance there is little chance of sticking, and they were satisfactory during the 10,000 miles test on SpectreCodename for Phantom III lll, this same set having been fitted to a production chassis which they report has cured the chatter. | ||