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).
Failures in S.U. petrol pumps, specifically relating to diaphragm issues causing noise and delivery failure.
| Identifier | ExFiles\Box 149\4\ scan0058 | |
| Date | 27th October 1936 | |
| 1263 To Hs.{Lord Ernest Hives - Chair} Rm.{William Robotham - Chief Engineer}2/JH.27.10.36. FILE ONLY. S.U. Petrol Pumps. We visited S.U.'s. 26.10.36. The situation is as follows. There are two main troubles, noise and complete delivery failure due to diaphragm failure. On the Bentley there is no reason to suppose that we are having more trouble today than since the inception of the S.U. pump. The attached curve shows that the number of complaints per week has not risen as fast as the number of cars on the road. There has been no sudden rise since the one and only change we made to the diaphragm, gut to seaweed base, (Gl{G. Linnett} type) last October. On the Phantom III and 20/25 the underbonnet temperature accentuates noise and diaphragm shrinkage. Whilst the Bentley diaphragm failures are about 10% of the total complaints, on the 20/25 the figure rises to over 30%. We have no reliable information from the Ph.III as yet. Therefore it is imperative that we change to a diaphragm that is not affected by temperature. This is the great virtue of the G.s zinc base the latest S.U. material. We have not run 15,000 miles on this material, to do so except in the summer would be futile. We must therefore accept Skinner's recommendation ( the guarantees less than 1% troubles) or wait 12 months for a standardisation test. The situation is so serious that the latter alternative does not seem to be feasible. We have therefore instructed Skinner to fit the new diaphragm forthwith to every pump delivered from now onwards, and to supply us with spares sufficient to fit G-3 material to 250 pumps. | ||