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 conducted on a Bensport petrol pump to investigate delivery deficiencies and potential improvements.
| Identifier | ExFiles\Box 27a\2\ Scan159 | |
| Date | 11th May 1933 | |
| X2677 To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/WB.{Mr Brazier/Mr Bell} c. to Wor.{Arthur Wormald - General Works Manager} c. to EY. Hs{Lord Ernest Hives - Chair}/WB.{Mr Brazier/Mr Bell}8/KT.11.5.33. BENSPORT PETROL PUMP Lec.3417. The pump used for these tests was built to EB.388, and was taken off B. No.2. engine unit - 3.B.IV. chassis. The suction system was modelled on the chassis arrangement, using the same lengths of 1/4" diameter pipes, and including a three way tap, and an FB.354 Enot's filter fixed at the same relative heights as on the chassis. After taking tests illustrating the increase of delivery obtained by increasing the diameter of the branched delivery pipe - Graph 1 - and also the decrease due to the carburetter head - Graph II - the 5/16" diameter delivery pipe was connected to two S.U. carburetter float chambers, using direct flow unions. By measuring the actual flow through the float chambers it was found that the delivery, relative to the free delivery (without the float chambers) decreased above a pump speed of 1000 R.P.M. until, at 2000 P.R.P.M. there was a deficiency of approx 30%, equivalent to 40 pts/hr. Removing the floats reduced this deficiency to approx. 15%, and no further decrease was obtained by removing the float needles, therefore this latter percentage was due solely to the restriction of the ports. With the floats and needles refitted, but with the float sunk to the bottom of the floatchamber, the deficiency still registered 15%, thus the additional 15% obtained with the floats free was due to float needle restriction by virtue of the float level - Graph III. When the "sunk float" test was repeated with the 1/4" diameter delivery pipe the reduction in delivery was similarly approx 15% of the free delivery obtained with the same pipe - Graph III. Since it was considered that 100 pts/hr. at 2000 P.R.P.M. - as obtained with 5/16" diameter delivery pipe, and "sunk float" - did not allow sufficient margin above the maximum engine consumption, a stronger pump pressure spring was fitted, giving a free delivery of 141 pts/hr. at 2000 P.R.P.M. with a 5/16" delivery pipe, the maximum pressure | ||