IN this paper Mr. Colwell portrays graphically and completely the development of American and European aircraft and automotive engine valves. Descriptions of present types include designs, materials, manufacturing processes, operation, and maintenance.
Three major developments are named as being responsible for the low valve temperatures and long service under high-output conditions of modern aircraft-engine valves: development of the sodium-cooled valve; development of forging technique; and cylinder-head design. In addition, three minor developments are mentioned: adoption of TPA austenitic steel for exhaust valves; use of stellite or a similar hard facing material puddled on the valve seat; and the use of TPA or Silcrome X-9 for seat inserts. Mr. Colwell explains that the sodium hollow-head and forced lubrication are American developments, whereas the austenitic steel, stellite, and steel seat inserts were first employed in England.
A needed major development, he adds, is a constant-clearance aircraft-valve mechanism which meets all the requirements sought in America. Data on research work on improving gas flow in the valve ports are presented for the first time.
Specific designs of valves discussed include Wright, Pratt & Whitney, Allison, Hispano-Suiza, Gnome-Rhone, Rolls-Royce, Bristol, B.M.F., Siemens, Junkers, Daimler-Benz, B.M.W., Bramo, Fiat, Alfa-Romeo, and Villar Perosa, as well as the Buick automobile valve.
