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).
Oil pressure issues and pump performance on the Spectre engine.
| Identifier | ExFiles\Box 149\2\ scan0089 | |
| Date | 11th December 1934 | |
| X64/4 338 To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}4/KW.11.12.34. SpectreCodename for Phantom III Oil Pressure. If after running at high speeds with an inlet temperature to bearings of 80°C. or over, the engine be idled at 250 r.p.m., the main oil pressure drops to nothing. With cold oil, the pressure at this speed is 35 lbs/sq.in. and at 65°C. is 2 lbs/sq.in. If the bye-pass through the main ball valve which ensures that oil be fed to the auto-adjusting tappets under any conditions be blanked, the pressure rises from 2 lbs/65°C. to 5 lbs/65°C. at 250 r.p.m. The pump flow has been checked with both hot and cold oil, the flow being 4 pts/min. at 250 r.p.m., and 8 pts/min. at 500 r.p.m., thus proving that there is nothing wrong with the pump by being proportionately correct. In conjunction with the additional big end bearings on this engine and the increased clearance necessary for lead bronze, a larger pump is necessary to maintain a pressure when running at low speeds with hot oil. The existing SpectreCodename for Phantom III pump is 11% larger capacity than the Phantom pump which with lead bronze bearings was too small at low speeds. At present, if the SpectreCodename for Phantom III be opened up when cold, the oil pressure is very high and reads over 50 lbs/sq.in. as low as 700 r.p.m. This indicates that the relief valve is too restricted to deal with the quantity of cold oil being circulated and any larger pump would accentuate this excessive cold pressure. By removing either the main spring and ball valve or the intermediate spring and ball valve, the same pressure of 50 lbs/sq.in. at 700 r.p.m. when cold is registered. With both ball valves removed a pressure of 35 lbs/sq.in. is obtained at 2,000 r.p.m. By packing up the spring retaining caps .200" the pressure is 30 lbs/sq.in. at 2500 r.p.m. | ||