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 explaining test findings and design considerations for a fuel pump and tank unit gauge system.
| Identifier | ExFiles\Box 44\3\ Scan152 | |
| Date | 14th January 1929 | |
| Messrs. Rolls-Royce, Ltd., Date 14.1.29. Page 2 or two, as soon as they are completed. We thought you would like to have the rest of the material in advance. Perhaps you would be good enough to explain this to your Technical Production Department, in case this material does not come to you direct. With regard to the pumps which we shall be sending you in the course of a day or two, we would like to explain the following points. By test we have found that the speed of replacing the air in the tank unit by means of the pump is not dependent on the rate of air delivered by the pump, but rather on the speed at which the petrol can get out of the tank unit, in conjunction with the speed at which the gauge can rise, owing to the necessary restriction in the capillary tube between the back and front legs of the "U" tube. To avoid altering the datum of the tank unit, the air must be delivered underneath the bell plate, below the datum level. The pump tube has accordingly been brought across the bottom of the tank unit, and the exit hole is directly underneath the larger hole through the bell plate, through which the air enters. Owing to the resistance in the air line, we have found that it is quite practicable to use a pump | ||