16 AIR COMPRESSORS 



AIR COMPRESSORS 



TYPES OF COMPRESSORS 



INTRODUCTION 



The first air compressor employed in connection with air 

 brakes, was a Cameron, steam-driven water pump, in which 

 the hydraulic cylinder was replaced by an air cylinder. This 

 pump demonstrated the practicability of operating brakes by 

 means of compressed air. The 6-in. compressor was the first 

 successful air compressor operated by steam that was furnished 

 as a part of the air-brake system. This type served its purpose 

 for several years, when the demand for greater pump capacity 

 brought forth the 8-in. compressor as its successor. This 

 provided sufficient pump capacity for a considerable period, 

 but eventually was succeeded by the Qj-in. compressor. Still 

 further demand for increased capacity brought out the 11-in. 

 compressor, and later, the 8|-in. cross-compound compressor. 

 The success of this cross-compound compressor in air-brake 

 service, was such that a larger compressor of the same type, 

 known as the lOJ-in. cross-compound compressor, was designed 

 for industrial service. The original 8-in. air compressor, now 

 obsolete, was an 8"X7i"X9" air compressor. This means 

 that it had an 8-in. steam cylinder, a 7^-in. air cylinder, and 

 a 9-in. stroke. The valve mechanism was in the side of the 

 steam cylinder instead of in the top cylinder head. The new 

 standard 8-in. compressor is an 8" X 8" X 10" compressor, and 

 has the same style of valve mechanism as the Q^-in. and the 

 11-in. compressors. 



8-IN. AIR COMPRESSOR 



The new standard 8"X8"X10" air compressor is shown in 

 Fig. 1 ; the left view being a side view showing a vertical cross- 

 sectional view of the main valve and bushing, and the other a 

 vertical sectional view of the compressor showing the back 

 half. The compressor weighs 450 Ib. The lift of the air 

 valves is &-in. for all valves. 



