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).
Test results and analysis of different fuel pump and plunger arrangements.
| Identifier | ExFiles\Box 179b\3\ img135 | |
| Date | 5th August 1933 | |
| -3- He/Pur.1/M.A.5.8.33. Cont'd.{John DeLooze - Company Secretary} The initial fuel supply is correct. (2) SAME AS (1) BUT WITH SPRAYING ORIFICE .031. Fuel is lifted to a height of 6ft, and is supplied for a period of 7 seconds or 4 seconds after full throttle has been obtained. Owing to the restriction of the .031 jet the rate of throttle opening is limited, owing to the pump acting as a dashpot and, acting against the operating mechanism may cause the mechanism to distort and become damaged. The initial quantity of fuel supplied is insufficient for any degree of acceleration. (3) PLUNGER FIXED RIGIDLY TO SPINDLE. PLUNGER GAP .015". SPRAYING ORIFICE .031". Results are same as (2) but the dashpot effect is much more pronounced. (4) PLUNGER FIXED RIGIDLY TO SPINDLE. PLUNGER GAP .015" WITH A LIGHT SPRING HOLDING PLUNGER FROM ITS SEATING. SPRAYING ORIFICE .031. In this case a light spring is inserted between the plunger and its seating, giving a permanent leak for all movements of the throttle in which the resistance of the fuel to the plunger is less than the spring pressure. When the resistance is greater than the spring pressure, the gap forming the leak is closed and pressure is exerted to supply fuel so long as the speed of throttle opening is maintained and demands increased fuel supply. When operated violently the .031" spray jet causes the pump to act as a dashpot similar to (3). (5) STD. PUMP ARRANGEMENT. MAIN PLUNGER SPRING PRESSURE REDUCED BY 25%. | ||