142 ENGINEER'S BRAKE VALVES 



to the bushing in which it works. Also clean the stem and 

 seat of the brake-pipe exhaust valve thoroughly, but leave no 

 oil on either, as it will catch particles of dirt and scale and 

 cause trouble. 



Rotary Working Hard. The chief causes of a rotary working 

 hard are: too free use of oil in the air end of the pump, or the 

 use of poor oil; constant use of the emergency position of the 

 valve, which tends to draw dirt and scale from the train pipe 

 on the rotary seat; a hot pump, the heat from which will cake 

 the oil on the rotary seat; the handle nut 7 being screwed down 

 so tight as to cause key washer 13 to bind on the top casing 

 of the engineer's valve; the gasket may be worn so thin that 

 the rotary key 12 rubs against the valve body. 



Lubricating Brake Valves. If the handle of either the 

 automatic or the independent brake valve does not operate 

 easily, the rotary valve or the rotary-valve-key gasket is prob- 

 ably dry from lack of lubrication. To remedy this trouble 

 when the brake system is charged, close the double-heading 

 cock in the brake pipe below the brake valve; also, close 

 the main-reservoir cock in the main-reservoir pipe. Operate 

 the brake valves to remove all pressure from them; then, 

 remove the oil plug in the automatic brake-valve body, 

 fill the hole with good valve oil, and move the brake-valve 

 handle from full-release to emergency position and back to 

 release position a few times, to work the oil between the rotary 

 and its seat. Again fill the oil hole and replace the plug. 

 Next, remove the cap nut from the top of the rotary-valve 

 key, fill the hole in the key with oil, push down on the key, 

 and move the handle a few times; then, again fill the hole with 

 oil and replace the cap nut. Treat the independent brake 

 valve in the same manner. 



