74 



AIR COMPRESSORS 



The reference numbers for the low-pressure steam piston and 

 high-pressure air piston are given in Fig. 4. The pistons and 



FIG. 4 



rings are designated by the diameter of the cylinder for which 

 they are suitable, proper allowance for clearance and fitting 

 being provided for. 



AIR-COMPRESSOR OIL CUPS 



Automatic, Air-Cylinder Oil Cup. 



The automatic, air-cylinder oil cup, 

 shown in Fig. 1, is furnished only on 

 special order. It is suitable for use 

 only on the 8-in. new-style, the 9Hn., 

 and the 11-in. compressors. Its weight 

 is If Ib. Each down stroke of the air 

 piston produces a vacuum that draws 

 a piston 7 down against the action of 

 the spring 8, this allowing a small 

 amount of oil to feed regularly into the 

 cylinder. The spring reseats the pis- 

 ton 7 as soon as the vacuum is suffi- 

 ciently reduced. The piece number of 

 the oil cup complete is 9,769; the 

 numbers of the various parts are as 

 follows : 



