CATALOGUE OF THE MECHANICAL ENGINEERING COLLECTION, 



39 



cylinder throujih these intakes is controlled by valves operated by 

 rods, which in turn are operated by appropriate cams on a shaft 

 receivini? motion from the crankshaft. The exhaust is in the under 

 side of the cylinder. 



The opening of the intake valve permits the gas to pass along 

 the intake passage to the cylinder. At one point in its travel the 

 gas passes over a hot platinum cup previously heated by the burning 

 of a portion of the gas obtained through a by-pass from the valve 

 box. The red-hot platinum ignites the gas and the resultant ex- 

 pansion forces the piston to the opposite end of the cylinder. Upon 

 reaching the end of the stroke, the intake valve at this end of the 

 cylinde? opens, admits gas which is similarly ignited, and forces 

 the piston back. Such is the cycle. The water in the tank serves 

 a variety of purposes. It keeps the engine cylinder sufficiently cool 

 for efficient operation— its temperature, however, is sufficiently high 

 to vaporize the turpentine-and it lubricates the piston rod and 

 prevents it from being overheated. Another interesting feature of- 

 the engine was the firing of the charge of gas by heated platinum, 

 rather than a naked flame, as practiced by earlier inventors 



Cat. No. 251,278 U.S.N.M. 



Model of G. B. Brayton Gas Engine. TJ. S. Patent, No. 125166, April 2, 

 1872. Transferred from United States Patent Office. 



The motive power for the engine is obtained by burning a mix- 

 ture of air and illuminating gas. The engine consists of a vertical 

 cylinder having a double-headed piston. Upon the down stroke ot 

 tiie piston a quantity of gas and air mixed is drawn into the upper 

 part of the cylinder, and upon the upstroke this same gas is forced 

 out of the cylinder under pressure into a receiving tank, which acts 

 as the supply tank for the gas to be used as the motive power. 



The pressure maintained in the supply tank is at least 60 pounds to 



the square inch. In the bottom of the cylinder below the reach of the 



down-stroke of the piston there are placed a number of wire gauze 



diaphragms. They serve to guard the passages through which the 



gas is supplied to the engine and cut off the flame after the gas has 



been ignited from the supply which is flowing from the tank when the 



valve connection is open. This valve is controlled by means of a 



revolving cam on the main shaft. The design of the cam determines 



the length of time that the valve remains open, a spring causing it 



to close upon the instant that the cam ceases to hold it open A 



constant flame of gas is maintained upon the upper surface ot the 



wire gauze diaphragms which serve to ignite each charge of the gas 



as soon as it passes through the diaphragms. Consequently, upon 



icrnition the steadv expansion exerts a true pressure upon the piston 



