SELECTING MACHINERY AND EQUIPMENT 319 



readily accessible parts, and ease of obtaining new parts are 

 major factors, just as in case of the pump. AVater-cooled 

 engines with a circulatory water system are standard. Air- 



cooled engines are used by some manufacturers. Magneto 

 ignition systems are standard equipment on the newer ma- 

 chines; they do not become deranged as easily as the older 

 battery systems, but it is well to have a battery system on 



{Rardie Mfg. Co.) 



Fig. 113. A trailer outfit operating by means of a power take-off from 



the tractor. 



hand to use in case of emergency, since the magneto system 

 when deranged may require the attention of an expert. 



A governor to control the engine speed as the load varies 

 is very desirable and makes it unnecessary to watch the engine 

 closely during the spraying operation. 



(Bardie Mfg. Go.) 



Fig. 112. The crankshaft transmits power to 

 the pump. It should have plenty of reserve 

 strength. 



