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).
Analysis of a G.S.S.C. pump failure on chassis GAR.14, suggesting causes other than weak springs.
| Identifier | ExFiles\Box 146\1\ scan0322 | |
| Date | 15th July 1938 | |
| 1263 also 1248 1245 W/P - Sr/VA. Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}1/JH.15.7.38. CHASSIS GAR.14. With regard to the failure of a G.S.S.C. pump on this chassis we are unable to agree that the failure was due to the springs being weak as stated in the report sheet P.92. It is unlikely that both springs should lose their poundage in the middle of a run and the fact that the pump restarted when the fitter arrived. The springs may be slightly below the usual poundage but this should have been apparent when the pump was first tested. From the history of the case we are inclined to suggest that the failure was caused by the armature rubbing or the spindle fouling which would become evident when the pump was hot, due to the reduced pull exerted by the magnet. The other alternative cause of the failure would be gummy valves which would lend to stick when hot and dry. If the head developed by a pump on the rig with no delivery is not up to standard we have found this in nearly all cases to be caused by the stiffness of the diaphragm rather than the spring. This stiffness acts in two ways (1) the hysterisis loss in the diaphragm opposes the spring force and (2) the stiffness increases the effective diameter of the diaphragm which for the same spring force will give a lower pressure in lbs. per square inch. Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} | ||