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).
Experiments and modifications to a Phantom II Petrol Pump, LCC 2951, to improve performance.
| Identifier | ExFiles\Box 17\5\ Scan108 | |
| Date | 25th January 1932 | |
| R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Bl. c. to Ss.{S. Smith} Mor. c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to W. 87460 Hs{Lord Ernest Hives - Chair}/Bl.6/MA.25. 1. 32. P.II PETROL PUMP. LCC 2951. When first supplied, this pump gave a delivery of only 20-40 pts/hr between 1000 and 2000 R.P.M. After numerous experiments with springs, valve ports, air vessels etc, it was found that the flow decreased with the speed between 750 and 1750 RPM with a tendency to rise again towards 2000 RPM. These characteristics were consistent in nearly every case, until a combined valve stop and small vessel - Hs.{Lord Ernest Hives - Chair}509 - was fitted to the outlet valve, the addition of which overcame the difficulty and the delivery increased with the speed. After obtaining a good delivery curve it was decided to fit a new set of standard 2.700" centre fabrics, before the pump was put on the engine. With these, it was observed that although the delivery was as good as, and even slightly better than the old set at the lower speeds, the plunger was not utilizing its full stroke even at slow speeds, and also that the maximum pressure (delivery tap closed) was over 6 lbs/sq. in. Fabrics having 2.800" centres were tried, with satisfactory results, but it was found necessary to regulate accurately the lowest plunger position so that the maximum pressure would not exceed 3.25 lb/sq.in. This lowest plunger position was found to be very critical, only a very slightly lower position than the final setting being required to increase the back pressure to 5/10/sq.in. Finally the pump was delivered to the fitters with the following modifications :- (a) Diameter of ports increase to .250" (as in Hs.{Lord Ernest Hives - Chair}508) (b) Additional bottle fitted over out-let valve (Hs.{Lord Ernest Hives - Chair}508) (c) Fabrics 2.800" centres. A small gauge was also supplied, so that the bottom of the stroke could be set to the same position as that finally determined on the rig. | ||