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).
Comparing the Stewart Vacuum Feed system with the Autovac system on a Phantom engine.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan286 | |
| Date | 12th December 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. ORIGINAL Expl. No. REF Hs{Lord Ernest Hives - Chair}/AJL/A.12. 12. 25. EXPERIMENTAL REPORT. To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/AJL. c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} OY. c. to EY. WOR{Arthur Wormald - General Works Manager}+ STEWART VACUUM FEED. X3831 X3579 We have received a note from OY. stating they had found that the uneven running of the Phantom engine due to the action of the Autovac was greatly reduced if the Stewart type Autovac was used. We therefore borrowed a Stewart Autovac to find the reason for this. The principle and action of the Stewart tank is exactly identical to that of the Autovac; the float controlled valve actuating mechanism is arranged in a different form which appears to have no advantages over the Autovac method - it contains more parts, takes up more room and is not so neatly carried out as in the Autovac. The attached sketches illustrate the method employed. When fitted to one of our cars, it was noticed that the effect of its action on the slow running of the engine was decidedly less than that produced by the Autovac. It was also noticed that the time taken to fill the Stewart float chamber, i.e. the time during which the induction pipe depression was opened to the surface of the petrol, was decidedly longer than in the case of the Autovac. An examination of the suction connection revealed the fact that the air exhausted from the tank had to pass through a hole approx. .065" dia. before entering the suction pipe contd :- | ||