SELECTING MACHINERY AND EQUIPMENT 



317 



satisfaction. Belts frequently slip, stretch, wear, or break. 

 A belt-driven machine may, however, be stopped quickly in an 

 emergency. 



{Bardie Mfg. Oo.) 



Fig. 110. The parts of the pressure-regulator 

 mechanism. 



Pumps require thorough and continuous lubrication. Oil 

 prevents the grinding and friction of metal parts and keeps the 

 packing pliable. Oil cups should be readily accessible, and the 

 oil feeds should be simple and direct. 



