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).
Conclusions from a pump test, outlining performance after 100 hours and detailing advantages and disadvantages.
| Identifier | ExFiles\Box 77\4\ scan0011 | |
| Date | 26th April 1917 | |
| H.R. 235a (500 T) (S.D. 408. 26-4-17.) Bm. 2/156/13. -5- Contd. (g) No change in flow was registered at the end of the 100 hours test. The pump was taken down and examined for wear. Worm gear, bearings and cams showed no signs of wear. Cam follower was very slightly worn on one side, due to being in-exact fit. 4. Conclusions. The flexible drive and bellows diaphragm are two important details in this pump. Neither of them are good engineering devices, being difficult and expensive to manufacture and liable to failure; a very grave fault in so vital a detail as the petrol pump. If the flexible drive is eliminated and a direct drive adopted this necessitates raising the pump which would increase the suction lift and so reduce the flow especially at high altitudes. Through the bellows diaphragm has stood up to the present tests it would be essential to have a number of long long duration tests with a series of diaphragms before the reliability could be demonstrated. The special advantages of the pump are:- (a) Self regulating for pressure, adapting it to feeding direct to the carburetter. (b) Being of positive pressure type, the discharge will remain the same at all altitudes. (c) No wearing surfaces in contact with the petrol (d) The disadvantages are :- (a) Large clearance, limiting the suction lift at which pump is self priming, to such a degree that it should be placed on a level with the bottom of the petrol tank. (b) In the pump under test weight and space are disadvantages which will be overcome in the new style pump. It would be advisable to make the lubrication of this pump more sure by providing a special properly marked lubricator. The present plug is difficult to get at and would be liable to neglect when the pump is placed inside the engine cowling. It was noticed that the anchorage for the spring in the pump body was insecure. This may be improved upon in the new type of pump. | ||