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).
The testing of a 'Grav-vac' vacuum petrol feed tank, detailing performance issues with its valve mechanism compared to the standard Autovac.
| Identifier | ExFiles\Box 40\3\ Scan086 | |
| Date | 10th July 1928 | |
| 43575 To ROY.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/AJL. Hs{Lord Ernest Hives - Chair}/AJLL/LG10.7.28. GRAV-VAC PETROL FEED. 43575 43579 Attached is a copy of our report on the Crav-vac vacuum feed tank submitted to us for test purposes. The tank was submitted to our usual vacuum tank tests for efficiency in petrol 'pumping' and as shewn in the petrol delivery curves is superior to the standard Autovac in this respect under all conditions. The troubles experienced, as stated in our report, are due to the valve change over mechanism not being sufficiently quick and positive. The consequences are rather disastrous, in one case we filled the engine with raw petrol drawn through the suction valve, the bell cyl. had not risen and operated the valves, or had risen and not closed the suction valve fully and opened the air release valve. In the other case, when running at high speeds the slight engine vibration was sufficient to prevent the air valve from seating securely and no petrol was delivered at all; when the tank was suspended in mid-air, i.e., in a vibrationless position, the trouble disappeared. We only know of one case of the first mentioned trouble occurring in the autovac tank - this was due to a punctured float, and the deficiency has been remedied by employing the self-draining float. The second trouble has never been recorded in the Autovac system. contd :- | ||