220 STEAM ENGINES 



getting a bad lot of oil sometimes. About the only safe way 

 to meet this trouble is to pay a fair price to a reputable dealer 

 for oil that is known to be of good quality, unless the purchaser 

 is expert in judging oils. 



Oil Squeezed Out of Bearings. Bearings carrying very 

 heavy shafts sometimes refuse to take the oil; or, if they do, 

 it is squeezed out at the ends of the brasses or through the oil 

 holes, and then the journal will run dry and heat. Large 

 journals require oil of a high degree of viscosity, or heavy oil, 

 as it is popularly called. Oil of this character has more diffi- 

 culty in working its way under a heavy shaft than a thin oil 

 has, but thin oil has not the body necessary to lubricate a 

 large journal. 



This difficulty may be met by chipping oil grooves or channels 

 in the brasses. A round-nosed cape chisel, slightly curved, is 

 generally used for this purpose; care should be taken to smooth 

 off the burrs made by the chisel, which may be done with a 

 steel scraper or the point of a flat file. The grooves are usually 

 cut into the brass in the form of a V if the engine is required 

 to run in only one direction; if it is to run in both directions 

 the grooves should form an X. In the first instance, care 

 must be taken that the V opens in the direction of rotation 

 of the shaft; that is, the grooves should spread out from their 

 junction in the same direction as that in which the journal 

 turns. The oil grooves may be about J in. wide and J in. deep, 

 and semicircular in cross-section. 



Grit in Bearings. Grit is an ever-present source of heating 

 of bearings, and only by persistent effort can the engineer 

 keep machinery running cool in a dirty atmosphere. The 

 machinery of coal breakers, stone crushers, and kindred indus- 

 tries is especially liable to be affected in this way. Work done 

 on a floor over an engine shakes dirt down upon it at some 

 time or other; hence, all floors over engines should be made 

 dust-proof by laying paper between the planks. If the engine 

 room and firerooms communicate, and piles of red-hot clinkers 

 and ashes are deluged with buckets of water, the water is 

 instantly converted into a large volume of steam, carrying 

 with it small particles of ashes and grit that penetrate into 

 every nook and cranny, and these will find their way intc the 



