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).
Unexpected troubles and potential causes of failure in petrol pumps.
| Identifier | ExFiles\Box 27a\2\ Scan106 | |
| Date | 12th September 1932 | |
| BG. } FROM R.{Sir Henry Royce} HS.{Lord Ernest Hives - Chair} } E.{Mr Elliott - Chief Engineer} } x2677. R1/W12.9.32. C. to WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} DA.{Bernard Day - Chassis Design} PETROL PUMPS. Since petrol pumps have given unexpected troubles, some of which have little logical explanation, and since we have existing for P.2. a repeatedly very satisfactory scheme of vacuum pump plus autovac, and because we shall be rebuilding our 40/50. in a year or two, I think we should not think of altering it. We have to consider J.3. and Peregrine, which are arranged definitely for petrol pumps, and we must make this system work reliably. I do not believe there has been any reason for failure in any of the pump designs supplied, but that the trouble has been with the installation, or faults in the construction or proportions, because the first one was very similar, and quite as good as the electrical, and the second one almost identical to the A.C. Obviously if one runs out of petrol some time is taken to repump, which in our case was so long that failure might appear to have taken place. Vapour pressure must affect any pump - A.C. or electrical- equally badly, in fact, one could expect it also to affect autovacs i.e. warm petrol behaves like very hot water, resulting in steam or gas on the suction side if the water or petrol is much below the pump. A slight leak back at the valves or diaphragm will result in failure, hence our original metal diaphragm with inverted resevoir to fill the clearance volume. I do not now believe that the clearance volume affects the result against the small head we have on the suction side of a car standing on the level. The most treacherous thing about these pumps, especially against self priming, is the small size of the valve and the relatively heavy valve spring pressure. You will notice that nearly all aero work is done with petrol pumps, but they have no valves and are generally self priming and probably the pipes and the petrol are not heated. HS{Lord Ernest Hives - Chair}/GRY.{Shadwell Grylls}, or someone who has time, should make a research with different brands of petrol, and generally go over all the problems relating to this question of petrol pumps. R.{Sir Henry Royce} | ||