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).
Considering the function and characteristics of accelerating pumps for car carburetters, with reference to a Stromberg aircraft model.
| Identifier | ExFiles\Box 122\1\ scan0071 | |
| Date | 11th June 1930 | |
| X4660 To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/ACL. c. to E.{Mr Elliott - Chief Engineer} c. to Rg.{Mr Rowledge} Hs{Lord Ernest Hives - Chair}/ACL.2/MJ.11.6.30. X4660 X4529. CARBURETTERS - ACCELERATING PUMPS. Considering the question of accelerating pumps for car carburetters we have been able to borrow the latest Stromberg Aircraft Carburetter Manual (this we have sent to E.{Mr Elliott - Chief Engineer}), which fully describes their latest form of spring loaded accelerator pump on pages 26 to 27. We notice that this pump discharges the accelerating fuel through the main diffuser - the pump system discharging into the main fuel passage after the main metering jet. The arrangement is better shewn in Fig.43. The main characteristics of this scheme appear to be :- (1) The discharge is prolonged after the throttle is fully open - while the engine is still gaining speed. This would appear to be even more useful in the case of a car accelerating on top gear than an airscrew accelerating to max. speed. (2) The amount of 'priming' depends upon the speed of opening of the throttle due to the leakage past the sides of the piston. At slow throttle openings there is no priming. Strombergs employ the pump priming system on their car carburetters but we do not know if it is of the same type as the aero carburetter. We think it is rather significant that most of the carburetter firms have now come to the accelerating pump, | ||