﻿Bui. 1136, U. S. Dept. of Agriculture. 



Plate III. 



Fig. I. — A Piston Type of Balanced Reducing Valve Especially 

 Adapted to Service in which the Flow of Steam Is Continuous. 



The low-pressure steam acts on the piston P in the cylinder and tends to close the valve V. 

 Loose weights hung on the horizontal lever counteract this tendency. The dashpot D steadies 

 the motion of the piston and valve, preventing bouncing. 



Fig. 2. — A Reducing Valve Used for a Wide Range of Pressures. 



The reduced pressure operates the diaphragm A under the main adjusting spring B, thus opening 

 and closing a small pilot valve C concealed in the plug under the diaphragm. The pilot valve 

 controls the admission of high-pressure steam to the space D between the two pistons E in the 

 bottom of the body; this steam forces the pistons E up and so opens the main valve F. When 

 the pilot valve closes, the high-pressure steam on the main valve F, the low-pressure steam on 

 the larger piston, and the valve spring all act to close the main valve. 



