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).
Letter to The AC Sphinx Spark Plug Co. regarding the trial installation and performance of their oil filters.
| Identifier | ExFiles\Box 135\3\ scan0171 | |
| Date | 3rd September 1937 | |
| 1139. Rm{William Robotham - Chief Engineer}/Swd1.5/MH.{M. Huckerby} The AC Sphinx Spark Plug Co., Dunstable, Beds. 3rd. September 1937. Dear Sirs, We thank you for your letter of the 23rd. inst. containing information regarding the installation of your filters for trial. Our decision has been to feed from the main pressure, 30lbs/square inch line and outlet into the valve gear line of 4lbs/square inch pressure. In this way no oil flowed by the pump at low speeds is wasted as under the conditions of hot oil and idling we cannot afford to do this. Regarding your query on this arrangement, the rocker oil will not be dependent upon the flow through the filter, as this is controlled by a relief valve, so that if the filter chokes it is immaterial to the normal supply. As stated in our previous letter, it is not our usual practice to tap off the main pressure line and would like you to confirm that there is no likelihood of the filter leaking or bursting under the pressure that it will be subjected to, that is, though 30lbs/square inch is normal, under extreme conditions where the engine is opened up with cold oil a pressure of 100lbs/square inch might be reached for a short period of time. The filter as housed in the manner described on one of our cars has, from appearances cleaned up the dirty oil quite appreciably. At the moment the samples of "before" and "after" oil are being analysed in our Laboratory, but they have some difficulty in finding | ||