TRANSMISSION OF POWER 2Q 



H. P. = Horse power, 



v = Velocity in feet a minute, 

 w = Width of belt in inches. 



H. P.=-=- 



IOOO 



The quantity v may be calculated from the number of 

 revolutions a minute and the diameter of the driving 

 pulley. The velocity of belts rarely exceeds 4,500 feet a 

 minute. The highest efficiency of belt transmission is ob- 

 tained from belting when there is no slipping and little 

 stretching, and when the tension on the belt does not 

 create an undue pressure on the bearings. 



41. Leather belting. Good leather belting will last 

 longer than any other when protected from heat and 

 moisture. A good belt should last for 10 to 15 years of 

 continuous service. Best results are obtained when the 

 hair or grain side of the leather is run next to the pulley. 

 When the belt is put on the opposite way, the grain side, 

 which is firmer and has the greater part of the strength of 

 the belt, is apt to become cracked and the strength of the 

 belt much reduced. 



42. Care of leather belts. Belts should be occasionally 

 cleaned and oiled to keep them soft and pliable. There 

 are good dressings upon the market, and others that are 

 certainly injurious. Neatsfoot oil is a very satisfactory 

 dressing. Mineral oils are not very satisfactory, as a rule. 

 Rosin is considered injurious, and it is doubtful if it is 

 necessary to use it on a belt in good condition. With 

 horizontal belts it is desirable to have the under side the 

 driving side, for then the sag of the slack side causes 

 more of the belt to come in contact with the pulleys and 

 will prevent slippage to some extent. 



43. Rubber belting. Good rubber belting is of perfect 

 uniformity in width and thickness and will resist a greater 

 degree of heat and cold than leather. It is especially well 



