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).
Analysis of the issues with vacuum, mechanical, and electrical fuel systems, concluding with the benefits of the AC Fuel Pump System.
| Identifier | ExFiles\Box 27a\2\ Scan011 | |
| Date | 12th August 1926 guessed | |
| AC SPARK PLUG COMPANY 1. Poor idling of the engine. The vacuum tank depends upon the suction of the engine for its action and a volume of air is admitted to the manifold above the carburetor intermittently, thus introducing erratic conditions in carburation. In other words, the carburetor must be adjusted rich enough to take care of the "lean periods" due to the extra volume of air which is admitted when the vacuum tank trips, and as a result this adjustment is entirely too rich when this vacuum source of air is shut off. 2. There is always a danger of filling the engine cylinders with raw gasoline when the vacuum tank mechanism fails to operate. This danger is present because of the direct connections between the gasoline tank and the engine. 3. The vacuum of an engine changes inversely with its load. The maximum power for lifting gasoline happens to be at the time when the least gasoline is required for the engine, namely, on idling. When maximum power is used on the other hand, the vacuum of the engine is very low and entirely insufficient to raise the fuel from the rear tank to the vacuum tank, hence the vacuum tank must be of large enough storage capacity to tide over periods when full power of the engine is used. 4. The size of the vacuum tank when mounted on the dash under the hood takes up considerable space and with the advent of the new devices such as oil filters and air cleaners it creates a crowded condition and sometimes a difficult problem of installation. (B) Other Systems. It is admitted that any fuel system which will overcome the above disadvantages would be highly desirable. Some attempts have been made in the past to solve this trouble by means of fuel pumps mechanically or electrically operated with but little success. For instance; 1. Mechanical Pumps - Their biggest source of trouble was due to the wide variation in speed under which such a device would have to operate also the difficulty of controlling the flow of fuel, which would vary directly with the speed of the engine while the consumption of fuel by the engine would vary at the same time with the load of the engine. Another source of trouble, if the foregoing problems were solved, is the condition to be met when a considerable supply of fuel is required in extreme cold conditions at very low speed, such as cold weather starting, etc. 2. Electrical Pumps - The biggest trouble in this field was in connection with the points of contact, and further in regard to the very unpleasant noise due to the intermittent action of the pump. 5. CONCLUSION The AC Fuel Pump System satisfactorily solves all problems and troubles, both of the vacuum systems and previous attempts in connection with mechanical and electrical fuel pumps. | ||