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).
Tests and modifications carried out on a Phantom II diaphragm petrol pump.
| Identifier | ExFiles\Box 17\5\ Scan060 | |
| Date | 12th March 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Lov.{Mr Lovesey} c. to Sg.{Arthur F. Sidgreaves - MD} Hcr. c. to Rg.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} By.{R.W. Bailey - Chief Engineer} X7460 Hs{Lord Ernest Hives - Chair}/Lev.2/KT.12.3.31. X7460 PHANTOM II. PETROL PUMP. We have carried out several tests on the P.II diaphragm petrol pump and during these tests made several modifications. In general, with the best results we have obtained, the pumping capacity is too small for continued full throttle operation at max. demands at certain speeds. The "pick up" from the two gall. reserve level after exhausting the main tank takes 5 mins. even with the engine rotated at 200 R.P.M. The starter motor rotates a hot engine at 100 to 140 R.P.M. For our tests we employed a petrol lift to the pump of 15" which is equivalent to a low petrol level in the rear tank. In the first place we could not get any consistent results with the bakelite valves, we consequently tried out .25 dia. ball valves. These gave considerably better results. Further experiments shewed that the best valve lift to employ was .050 and the lightest valve springs which would just hold the ball valves on their seats. This was particularly important in the case of the inlet valve as a slightly stronger spring would considerably reduce the quantity of the fuel delivered. A further improvement was effected by increasing the compression ratio of the pump. This we did by filling up as much as possible the space in the top of the bellows, by means of a brass plate suitably cleared away for inlet and outlet valves and just clearing the moving end of the bellows. Two further improvements were obtained by increasing the size of the inlet ports in the valve body and by removing the filter in the inlet pipe. At 2500 R.P.M. the former increased the flow from 50 pts/hr to 64 pts/hr and the latter further increased it to 86 pts/hr. Appended curvex shows the delivery of the pump at various speed and on the same curve is given the max. full throttle engine demand. For comparison we have also shewn the delivery of an A.C. pump. It will be noticed that there is a sudden drop in the flow at 1500 R.P.M. At the moment we are at a loss to account for this but are investigating this point. | ||