CHAPTER XI. 

 LUBRICATION. 



The life of a machine and ease of operation 

 depend in a large measure on the manner in which 

 its journals are kept lubricated. 



In selecting lubricants keep in mind the purpose 

 for which they are to be used. In hot, dry weather 

 a thicker and heavier oil can be used than in cold 

 weather. In places or bearings subjected to external 

 heat, mineral oils are preferable to those containing 

 animal or vegetable matter. There is a tendency 

 among dealers to supply the cheapest quality of oil, 

 which usually proves the dearest to the buyer. 



In many of the machine oils vegetable matter 

 mixed with kerosene or other light mineral oil is 

 used as it can be sold very cheaply. The kerosene 

 soon evaporates at the ends of the journal, leaving 

 the vegetable matter in the box where it thickens and 

 gums, causing the box to heat or the shaft to run 

 hard. Oil of this nature is hard on paint, where it 

 spreads out over the woodwork, causing the varnish 

 to corrode and become dull. 



A good grade of oil for general purposes is what 

 is known as black or crude oil. It is a mineral product 

 with all the light oils removed, and may be had of 

 different grades of density. The heavier qualities 



70 



