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).
Letter discussing the necessity of fitting an air pressure relief valve, citing examples from Cadillac and environmental factors.
| Identifier | ExFiles\Box 125\1\ scan0018 | |
| Date | 28th July 1921 | |
| cc Mr. Belnap. Mr. Nadin. July 28th. 1921. CY2/G28.7.21. Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Attention Mr. Royce. Dear Sir, RE AIR PRESSURE RELIEF VALVE. Mr. Royce will recall that I wrote on Sept. 24 '20 for his attention, suggesting the use of a sylphon thermostat for pressure relief and delivery valves on the air-pressure system. I now find that the Cadillac uses a relief valve of this types, as shown:- See X.1092 for sketch. This has the advantages of the pre-war relief valves as far as the diameter of seating is concerned, but gets away from the danger of sticking by the use of a sylphon tube. The Cadillac use a limiting pressure pump like our own, which should not exceed 3 lb. pressure, but they still think it necessary to provide a relief valve. As I wrote to Mr. Royce, we also think it necessary to fit a relief valve, because of - (a) Expansion of air in the tank in strong sunlight, which has been known to raise the pressure to 8 lbs. in a few mins. (b) Change of altitude. For example, we have an inquiry from a mining engineer who uses cars over 50 miles of sand roads climbing 13000 ft. in that distance. At the top of the climb he is over 16000 ft. above the sea level, in an atmosphere of 9 lbs.sq.in. Shade temperatures reach 180°F, and there is a range of 70°F between night and day. contd:- | ||