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).
Notice explaining the operation of the three-way switch for the S.U. petrol pumps.
| Identifier | ExFiles\Box 149\4\ scan0177 | |
| Date | 29th January 1937 | |
| W/S. Cx.{Major Len W. Cox - Advertising Manager} from Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} 1263 Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}6/R.29.1.37. The Three-way Switch for the S.U. Petrol Pumps. The Rolls-Royce S.U. pump consists of two separate pumps combined for convenience into a single pump, and cases have occurred where a customer has been running for a considerable period unaware that only one pump was working. If the remaining unit then failed, the car would be stranded on the road. To guard against this possibility, a three-way switch has been fitted to the instrument board marked A.{Mr Adams} Both and B. For general running, the position marked "Both" should be used, and a check on each separate pump made periodically by running for at least a few miles in the A.{Mr Adams} and B. positions, when the single unit will deliver sufficient petrol for a speed of at least 60 m.p.h. It is no use switching off one pump momentarily, as the engine will continue to run for some time on the petrol in the pipes and float chamber. It is inadvisable to run on one unit only keeping the other in reserve as there is a possibility that when standing idle for long periods in a warm under bonnet temperature without a flow of petrol passing, the unit which has been held in reserve will fail to function when required. Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} | ||