DRIVES AND CONTROLS 



239 



■le achbn 

 maies quick 

 make and 

 break , 



/ 



Round confaci- causes 

 rapid increase in arcing 

 disi-once and quick 

 break of arc 



Fig. 491. — A special design of built-up switch of the self-opening type and provided with a locking pin, similar to 

 that shown in Fig. 489. Common to all the designs shown here, the switch is now obsolete in favor of fully enclosed 

 and easily replaceable switch units. 



Fig. 492. Fig. 493. 



Fig. 492. — A modern-type commercial switch mounted in a side handle. Such switches are readily replaced as a 

 unit, inexpensive, and sealed against the entrance of dirt. The switch opens as soon as the trigger is released unless 

 the locking pin is set, in which case a slight pull on the trigger releases the locking pin and opens the switch. 



Fig. 493. — Another example of a modern commercial switch mounted as a unit in a grip-type end handle. 



