390 



AIR GAUGES 



The 5-in. single-pointer air gauge, Piece No. 23 ,369, and shown 

 in Fig. 3, has a brass case with a silvered dial; it is used with 

 schedule SWA engine equipment and for general purposes. 

 The weight is 3 Jib. 



The 3f-in. single-pointer air gauge, Piece No. 19,100, and 

 shown in Fig. 4, has a cast-iron case with a silvered dial; it is 

 used with SWA engine equipment, and for general purposes. 

 The weight is 2 Ib. 



The inspector's test gauge, Piece No. 20,458, and shown in 

 Fig. 5, has a brass case with a silvered dial and nickel-plated 



cap. The weight is 1 Ib. Without the cap, the piece number 

 is 20,976; with a spring cap, 20,975, the piece number of the 

 coupling device for the inspector's test gauge, which will fit any 

 size standard hose coupling is 13,775. 



DUPLEX AIR GAUGE 



A duplex air gauge, which indicates both brake-pipe and 

 main-reservoir pressures, is located in the engine cab, in a posi- 

 tion convenient for the engineer. This gauge which is shown 

 in the accompanying illustration, consists of two gauges com- 

 bined in one, the same dial serving for both hands. The left- 

 hand gauge, which connects with M, operates the black hand. 

 This hand is said to represent brake-pipe pressure; although 

 M has a pipe connection to chamber D and the equalizing 

 reservoir; there is direct connection between the equalizing 

 reservoir and the brake pipe in release and running positions, 



