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).
Clarifying the terminology of oil 'filters' versus 'strainers' and discussing various oil cleaning technologies.
| Identifier | ExFiles\Box 44\1\ Scan297 | |
| Date | 17th April 1929 | |
| Sg.{Arthur F. Sidgreaves - MD} X9037 BY8/G.17.4.29. c. Hs.{Lord Ernest Hives - Chair} OIL FILTER. Referring to Sg{Arthur F. Sidgreaves - MD}8/E16.4.29. and OY/11 of April 5th OY. has been misled by our use of the term 'filter'. We have always called our oil strainers 'filters' - as a matter of fact it would be technically better described by the use of the word 'strainer', as all that the part in question does is remove relatively large pieces from the oil supply. With this explanation it will be clear that the D.O. report on experimental work going through was dealing with the engine oil strainer in the bottom of the crankcase, particularly as to the position of the oil inlet. We are well acquainted with the 'Auto Klean'. This scheme is evidently a development of a proposal which was later patented by Professor Hele Shaw. He found in carrying out certain technical experiments that a cartridge of paper discs tight up gave more effective filtering than any scheme he had previously known of. He therefore took out protection on the design, and it is being marketed in this country as a working proposal for oil cleaning purposes. Generally, I believe it is a by-pass scheme as used in this country, but in any case it is certainly very effective. For some long time now, approximately 2 years, we have been using a centrifugal dirt separator on the oil used by the engines on the dynamometer tests. We actually use a De laval separator in series with the oil, so that any dirt is automatically trapped and prevented from circulating round the engine. By this means we eliminate all dirt from the engine system except any particles which may lie in the oil pipes between the pump and the crankshaft. These we give special attention to, and the result has been we have practically perfect bearings free from scoring on all our engines as ready for delivery where previously a fair amount of scoring took place on most bearings. P.S. Since writing the above, I have been able to find some further information. The 'Auto Klean' is marketed in this country by the Streamline Filter Co. Ltd., 45 Horseferry Road, Westminster, London, S.W.1. In their system packs of paper washers are used, and so effective is the filtering that BY.{R.W. Bailey - Chief Engineer} even colloidal carbon which passes an ordinary filter paper is arrested by these filters. A special small filter is produced by the people referred to for use on Autocars. The filters can be cleaned by reversing the direction of flow and using air instead of oil. | ||