THE TURBINE ENGINE 255 



The Westinghouse Air Brake company, at Wilmcrding, 

 Pa., put the first steam turloine in America of larf!:c size into 

 operation, using it for their electrical power distriljution. 



The turbine engine, however, w^hile rapidly forging 

 towards the front rank of power producing machines is still 

 more or less in the experimental stage, as will be explained 

 hereafter. The steam engine, for all its complicated mechan- 

 ism, is the most w^idely knowTi of all the really useful power 

 machines. The steam engine is a reciprocating engine, that 

 is to say, the power produced by the steam is a backward and 

 forward motion, transformed to a rotary motion by a crank 

 attached to the piston at one end and a point between the 

 center and circumference of a fl}^ wheel at the other. There 

 are many forms of steam engines, but all work on the same 

 principle. Steam is admitted through a sliding valve to one 

 end of the cylinder in which the piston head is set. The pres- 

 sure of the steam forces the piston head along the cylinder 

 towards the other end. When it has traveled about one 

 third of the distance the hole through which the steam was 

 admitted, called a port, is closed by the sliding valve, which 

 is moved automatically. The expanding force of the steam 

 drives the piston head to the end of the cylinder, and as it 

 reaches there a port is opened and steam is again admitted, 

 this time on the other side of the piston head. Simultaneously 

 the valve uncovers a third port through which the steam 

 already used escapes into the open air or is returned to the 

 boiler to be used again. In compound engines this steam, 

 which has not yet lost its expanding power, is admitted into 

 a second, third, and occasionally a fourth cylinder before 

 returning to the boiler. Five cjdinder engines are not con- 

 sidered successful although used in several ocean going 

 steamships. The power that is developed by the steam work- 

 ing against the piston head is transferred by the piston and a 

 crank to a fl}' wheel, whence it is distributed by belts and pul- 

 leys or inter working gears to various machines. 



In theory the steam engine is simple; in practice it is 

 extremely compUcated, and the wear upon the different work- 

 ing parts, of which there are a great number, makes it an 

 expensive machine. In spite of efforts to perfect it the steam 



