148 ENGINEER'S BRAKE VALVES 



be screwed in to increase the pressure at which the valve will 

 close, and screwed out to reduce the pressure. To adjust 

 the wheel, first slacken screw 23 and turn the adjusting wheel 

 until the valve is adjusted properly for the desired lower 

 pressure. Then move the outer hand wheel stop 22 until it 

 comes against the pin in the wheel and fasten the stop in 

 this position on the spring case 15 by means of screw 23. 

 Next, turn the hand wheel 20 in the opposite direction until 

 the valve is adjusted properly for the desired higher pressure 

 and then move the inner hand-wheel stop 21 around to bring 

 the stop against the pin in the wheel and secure it in that 

 position with screw 23. Once the feed-valve is adjusted for 

 the proper high and low pressures, the pressure in the feed-valve 

 pipe can be quickly changed from high to low or from low to 

 high by simply turning the regulating wheel so as to move the 

 stop-pin from stop 21 to stop 22 or from stop 22 to stop 21. 

 If it is desired to carry a pressure between the low and the 

 high pressure, the wheel can be stopped at any point between 

 the stops 21 and 22. 



Care of B-6 Feed- Valve. In order that the feed-valve may 

 perform its functions properly, it is necessary that it be cleaned 

 and oiled occasionally. If the feed-valve is to be cleaned when 

 the air-brake system is charged with air, it must be relieved of 

 all pressure before it can be taken apart. To do this, close the 

 cut-out cock in the brake pipe underneath the brake valve, so 

 as to save the air in the brake pipe, and place the brake valve 

 in service or emergency position to empty the feed-valve and 

 the short piece of brake pipe above the cut-out cock; the feed- 

 valve may then be taken apart and cleaned. Clean both the 

 piston 6 and its cylinder, and the supply valve 7 and its bushing, 

 very carefully, leaving no lint on the parts, for it will cause 

 trouble; clean, also, the regulating valve and its seat and the 

 hole in the regulating-valve cap nut into which the regulating 

 valve extends. 



In oiling the supply valve, only a small amount of valve 

 oil, vaseline, mutton tallow, or some similar lubricant shoulc 

 be used, the oil being applied with the finger. Only a very 

 small amount of some light lubricating oil (engine oil will do) 

 should be used on the supply-valve piston and its cylinder, 



