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).
Crankcase ventilation tests conducted on Oldsmobile and Wraith engines.
| Identifier | ExFiles\Box 132\3\ scan0108 | |
| Date | 14th September 1938 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Da{Bernard Day - Chassis Design}/JNR.{Charles L. Jenner} Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager}6/JH.14.9.38. CRANKCASE VENTILATION TESTS ON OLDSMOBILE AND WRAITH. We have carried out tests enquiring into the method of breathing the Oldsmobile and Wraith engines. The Oldsmobile engine is fitted with an oil filler on the near side of the engine, which is open to atmosphere through a gauze filter. An extractor breather pipe on the off side is carried down from the crankcase through the tray. From the tests taken we found there was a slight intake of air through the oil filler when the engine was running light. This could be observed, but not measured. As the throttle was opened and the load increased the flow changed direction until at the higher speeds it was possible to measure a slight outward flow from the filler. From the attached crankcase pressure curves, it will be seen that while up to 30 m.p.h. the crankcase was at atmospheric pressure, above this speed a slight positive pressure was registered, there was therefore no inducement to take in air through the filler. The flows which we took from the extractor pipe at varying speeds were the result of crankcase back pressure. WRAITH. Where the Oldsmobile has both an inlet and outlet to the crankcase the Wraith has just the one breather pipe from the oil filler down through the undershield. We have been asked to find some method to obtain a negative pressure in the crankcase which will continually change the atmosphere therein and rid the crankcase of the undesirable properties present in the oil vapour which have harmful effects on cylinder bores. A negative pressure also has the effect of minimizing any tendency to leaks from the crankcase. | ||