FARM MACHINERY 307 



better grades of spraying outfits. Since these are more 

 accessible than the usual double-acting pump, they are mor^ 

 easily packed. The triplex pump furnishes a more even 

 flow of liquid, but introduces extra parts and is undoubtedly 

 of more expensive construction. The air chamber should 

 be designed to suit the kind of pump used. 



The Drive. The drive from the engine to the pump is 

 either a gear or a combination of gear and belt. If a gear 

 is used, it is highly essential that the pump and the engine 

 be mounted upon the same base, thus insuring more rigid 

 construction. 



Agitator. The most efficient type of agitator for power 

 sprayers is the propeller type. The small screw propellers 

 in the tank cause the liquid to circulate rapidly over and 

 over in the tank, carrying the heavy particles in the spray 

 mixture to the surface. Dash or paddle agitators do not 

 produce this action. 



The relief valve is one of the most sensitive parts of the 

 modern sprayer. Its purpose is to regulate the pressure, 

 allowing the surplus liquid pumped to return to the tank. 

 The regulator valve, used in place of the relief valve and 

 which cuts off the flow to the .pump after a certain pressure 

 has been reached, is a commendable device, as it relieves the 

 engine of part of its load and thus reduces the wear upon it. 



Tank and Truck. The tank and truck should be given 

 careful consideration. In general, the machine which may 

 be moved about the most easily is the most desirable. For 

 this reason, lightness is one of the requisites of a good spraying 

 rig. As the sprayer must be hauled over soft ground, high 

 wheels with wide tires foi the truck are desirable. The con- 

 struction should permit turning in very limited space. 



Accessories. The hose, extension rods, nozzles, cut-offs, 

 and other accessories are the things with which the operator 



