SELECTING MACHINERY AND EQUIPMENT 



315 



expanding type of material creating suction or pressure as it 

 works back and forth, or the packing may be stationary at the 

 end or top of the cylinder, fitting closely about the piston 

 so as to prevent leakage. In the latter type a smooth metal 

 plunger is used. In either case, the wear is intended to come 

 on the soft, expanding material which is easily replaced, rather 

 than on a hard metal part. Pack- 

 ing materials may be hemp, com- 

 position, candlewickj etc., treated 

 with oil or graphite to soften 

 them. 



The air or pressure chamber 

 is an essential feature of the 

 pump. The spray material en- 

 ters the chamber under pressure ; 

 the air is compressed and aids in 

 maintaining an even flow of the 

 material to the nozzles. The 

 size of the air chamber should 

 increase with the size of the out- 

 fit. The pressure gage is mounted 

 on the air chamber. 



Uniform pressure is further 

 insured by the pressure regulator 

 (Figs. 110 and 111). In its best 

 form it opens when a certain 

 pressure has been reached, re- Fig. 107. The detail of a pump 

 turning part of the spray ma- cylinder, 

 terial to the tank, and closes 



when the pressure falls below this point. Variation in 

 pressure is thus taken up in the machine, and the flow of 

 material at the point of application to the trees remain 

 uniform. 



The pump may be operated by chain, by belt, by yoke, 

 or by gear. Gear-driven machines, rigidly mounted, are 

 standard, though chain and yoke machines have also given 



OIL WICK 

 SHIMS 



DIE CAST BEARING 



DROP FORGED 

 CONNECTING ROD 



PLUNGER BODY 



GUIDE 

 OIL POCKET 

 LOCK SCREW 

 PORCELAIN 



LINING 

 WRIST PIN 

 BUSHING 

 OIL POCKET 

 STEEL TUBE 

 NO LEAK 



CUP 

 CUP FOLLOWER 



COTTER PIN 



{Bardie Mfg. Co.) 



