STEAM ENGINES 215 



when not needed to admit air. A broken valve, a piston loose 

 on its piston rod, and a piston rod loose in the crosshead will 

 all cause pounding in the circulating pump; they should be 

 treated in the same manner as was specified for similar troubles 

 in the air pump. 



HOT BEARINGS 



Mixtures for Reducing Friction. Should any of the bearings 

 show an inclination to hsat to an uncomfortable point when 

 felt by the hand, the oil feed should be increased. If the 

 bearing continues to get hotter, some flake graphite should be 

 mixed with the oil and the mixture should be fed into the 

 bearing through the oil holes, between the brasses, or wherever 

 else it can be forced in. A little aqua ammonia introduced 

 into a hot bearing will sometimes check heating by converting 

 the oil into soap by saponification, soap being an excellent 

 lubricant. Mineral oils will not saponify. 



Danger of Increasing Heating. If, after trying the remedies 

 just mentioned, the bearing continues to grow hotter, to the 

 extent, for instance, of scorching the hand or burning the oil, 

 it indicates that the brasses have been expanded by the heat 

 and that they are gripping the journal harder and harder 

 the hotter they get. At this stage, if the engine is not stopped 

 or if the heating is not checked, the condition of the bearing 

 will continue to grow worse as long as the engine is running, 

 and may become so bad as to slow down and eventually stop 

 the engine by excessive friction. By this time the brasses 

 and journal will be badly cut and in bad condition generally, 

 and the engine must be laid up for repairs. 



Remedies for Increasing Heat. The state of affairs just 

 mentioned should not be permitted to be reached. After 

 the simple remedies previously given have been tried and 

 failed to produce the desired results, the engine should be 

 stopped and the cap or key of the hot bearing should be slacked 

 back and the engine allowed to stand until the bearing has 

 cooled off. If necessity requires it, the cooling may be hastened 

 by pouring cold water oil the bearing, though this is objection- 

 able, as it may cause the brasses to warp or crack. Putting 

 water on a very hot bearing should be resorted to only in an 

 emergency, that is, when an engine must be kept running. 



