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).
From S. Smith & Sons discussing the design principles of oil filters, including the texture of the cleaning element and maximising surface area.
| Identifier | ExFiles\Box 135\3\ scan0211 | |
| Date | 5th January 1938 | |
| RP.290 S. SMITH & SONS (MOTOR ACCESSORIES) LTD. CRICKLEWOOD WORKS. Memorandum for inter-house correspondence only. To. MR. NICHOLS From. MR. GROSE Date. 5/1/38 - 2 - I do not wish to infer that its efficiency is not as good as ours, this is entirely a matter of the closeness of the texture of the cleaning element, but here again, if the texture of the material is very close, then the flow of oil will be very small, possibly insufficient to maintain clean oil in the sump, because even the smallest amount of carbonaceous matter on such a surface would easily choke it. Alternatively, a more open texture material would not deliver clean oil immediately, but would take time for the carbonaceous matter to fill up the pores and so make it a perfect Filter. I suggest that you send Mr. Robotham one of our Filter booklets where he will find all the information he requires in regard to the filtration of oil by means of a bypass Filter. We must make one point perfectly clear to Mr. Robotham, namely, that the oil flow of the filter is entirely dependent on its surface area and it should be the object of the designer of an Oil Filter to aim at getting maximum surface area in the smallest possible space. I return your papers herewith. | ||