Letter discussing the need for a relief valve due to high altitude, sand, and temperature extremes, referencing Cadillac systems.
| Identifier | ExFiles\Box 81\2\ scan0011 | |
| Date | 15th February 1916 guessed | |
| -2- 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 sun- light, which has been known to raise the pressure to 8 lbs. in a few minutes. (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 sea level, in an atmosphere of 9 lbs.sq.in. Shade temperatures reach 180°F, and there is a range of 70°F. {Mr Friese} between night and day. The present pressure system without a relief valve would not be safe under these conditions, and the pre-war relief valve would stick because of the sand in the air. It would therefore be necessary to use some such scheme as the Cadillac. It would also be necessary to reduce the compression space of the air pump in order to pump a high enough pressure at the high altitudes. This can be easily arranged by an aluminium plug on the cylinder cap. These are not exceptional conditions except that the cars in this particular case will be called upon to operate continuously under these conditions. Pikes' Peak is 14000 ft. and there is a road to the top much used by summer tourists. There are a hundred other mountains with roads up them running from 6000 ft. upwards. Sand road conditions and hot sun conditions are met in all parts of the U.S. It therefore seems highly desirable to incorporate a relief valve somewhat on the lines of the type shown. Mr. Belnap has had long experience with Cadillac cars, and states that he has known the air pressure on these cars to keep up for two months. It is not known what type of air pump delivery valve the Cadillac uses. Yours truly, ROLLS-ROYCE OF AMERICA, Inc., per M.Olley. MO/G. | ||
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).