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).
Petrol supply failures in S.U. pumps, focusing on diaphragm trouble and noise.
| Identifier | ExFiles\Box 149\4\ scan0062 | |
| Date | 27th October 1936 | |
| 371263 To Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} c. to Roy.{Sir Henry Royce} Rm.{William Robotham - Chief Engineer}1/AP.27.10.36. FAILURE OF PETROL SUPPLY : S.U. PUMPS. There are two main troubles - (1) Diaphragm trouble - this can cause a complete breakdown. (2) Noise. (1) Diaphragm Trouble. The diaphragm is equivalent to the pump piston. For nearly three years we have been using a gut material. This year we changed to a seaweed base. Both these materials are affected by temperature in that they tend to shrink if hot. The pumps get hotter on the 25/30. and Ph.III. than on the Bentley. This seems to be the basic cause of the present serious position. When the diaphragms shrink the pump may fail completely. We have little evidence that when used on the same car i.e. the Bentley our new diaphragm is any worse than the old one. Neither, however, has a good record and it is clear that when the operating temper-ature rises as on the two R.R. models the situation becomes impossible. It is therefore imperative that we change to a diaphragm that is unaffected by temperature forthwith. The S.U. Company have now a supply of such material known as G.3. which they are prepared to guarantee, and we have instructed them to fit this to all pumps which are delivered from now onwards. We have no alternative but to take their recommendation, because if we ran a 15,000 miles test under winter conditions it would tell us little, and we cannot afford to wait until next Summer. The S.U.Company have twelve months experience on production of the material in various stages of development and since January it has been fitted to the whole Morris range. They are so satis-fied with it that they are most anxious that we should change over. With regard to cars on test, at the coachbuilders and already delivered there are about 500 - 25/30s. and 220 - Phantom.III.s. to which the new diaphragms ought to be fitted as soon as possible. We are arranging with S.U.s. to have a float-ing supply of pumps which are up-to-date and which can be changed -continued- | ||