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).
Article on a new oil filter by Smith Accessory, reprinted from The Automobile Engineer.
| Identifier | ExFiles\Box 135\3\ scan0218 | |
| Date | 27th August 1937 guessed | |
| A NEW OIL FILTER Extremely Effective Cleaning by the New Smith Accessory (Reprinted by courtesy of THE AUTOMOBILE ENGINEER.) For some time Messrs. S. Smith and Sons (Motor Accessories), Ltd., have been experimenting with a type of filter which is claimed to be the most efficient filter so far discovered. It is stated that throughout its working life, which is approximately equivalent to 10,000 to 20,000 miles running, clean bright oil is maintained in the sump. The eventual clogging of the filter after this mileage is clearly indicated by the oil becoming discoloured, and may be easily seen by the eye on a polished chromium-plated dipstick; this indication being the warning that the filter requires replacing. The new filter is of the shunt type, i.e., a proportion only of the oil circulated by the pump passes through it. Thus when the filter clogs, or a stoppage occurs in the pipes, there is no danger to the engine. It is usually fitted by teeing in to the oil gauge pipe as near the pump as possible, and running a return pipe to the sump at some convenient spot. The construction of the Smith Oil Filter is shown in Figs. 2 and 3. The filtering medium consists of specially prepared paper, two circular papers with central holes (see Fig. 4) being separated at the centre by two brass washers, one of which has a series of raised pips on one face to space it from the companion washer. The filtering papers are securely fastened together at the periphery, and the unit is threaded on to a hollow and perforated stem. A spacing washer (Fig. 5) is also fitted between each pocket. The filter pack is made up of a number of these units, and the whole sealed into a container carrying the inlet and outlet nozzles. Dirty oil enters the container and filters through the surface area of the double-faced units; the clean oil passes between the two papers, through the washer spacers to the central stem and back to the sump. Fig. 8. Magnetic material extracted from oil sump Fig. 9. Sample of oil extracted from sump before filtration. 100 magnifications. Fig. 10. Impurities in oil from commercial lorry. 27 magnifications. Fig. 11. Oil after filtration. 200 magnifications. | ||