Lubrication

—-1. In machinery, to cause to slip easily; to supply to moving parts and their bearings, grease, oil or other lubricant, for the purpose of le ening friction. 2. The theory of lubrication is the interposition of a film of unguent betweer the two surfaces which are supposed to rub together by reason of the motion Of one of them. The friction of the surfaces on the unguent is le than their friction on one another, so that lubrication le ens friction, saves power and diminishes the risk of damage, wear and tear. For steam cylinders, air compre ors, etc., a lubricant with a high flash point or temperature of decomposition, and great viscidity is needed, qualities found in mineral oils only; heavy bearings require an oil with great weight and body, so that it shall not be squeezed out by the pre ure; small high speed arts require a thinner oil. hese latter qualities are provided for by different compounds of animal and vegetable oils, with some mineral additions.