JO ROUGH-AND-TUMBLE ENGINEERING 



the end of the backward stroke, it has driven the water 

 all out. It then starts forward again, but the water 

 which has been driven through the second check cannot 

 get back and this space is again filled from the supply. 

 The first four or five strokes of the plunger are required 

 to fill the pipes between the second check valve and the 

 hot water check valve. If the gauge shows 100 pounds 

 of steam, the hot water check is held shut by 100 pounds 

 pressure, and when the space between the check valves is 

 filled with water, the next stroke of the plunger will 

 force the water through the hot water check valve, 

 which is held shut by the 100 pounds steam pressure so 

 that the pump must force the water against this hot 

 water check valve with a power greater than 100 pounds 

 pressure. If the pump is in good condition, the plunger 

 does its work and the water is forced through into the 

 boiler. A clear sharp click of the valves at each stroke 

 of the plunger is certain evidence that the pump is work- 

 ing well. 



The small drain cock is placed between the horizontal 

 checks to assist in starting the pump, to tell when the 

 pump is working, and to drain the water off to prevent 

 freezing. When the pump is started this drain cock 

 should be opened, and the hot water in the pipes drained 

 off. The globe valve should then be opened. After a few 

 strokes of the plunger, and water begins to flow out 



