304 AGRICULTURAL ENGINEERING 



suction pipe extends to the lowest point. It is an advan- 

 tage to have the pump low, as the handle is then in a more 

 convenient position. If the holes cut for the pump and the 

 filling funnels are not too large, a barrel in a horizontal posi- 

 tion, with two heads, is more rigid and less likely to go to 

 pieces when empty for a time. 



All the working parts that come in contact with the 

 spray solution should be brass, as it is the only metal in use 

 dggfe which will resist the corrosive 



action of some of the solutions 

 in common use. The valves 

 should be either ball or poppet, 

 with removable seats. The ball 

 valve seat may be replaced for 

 a nominal sum, making this 

 part of the pump as good as 

 new. Brass poppet or disk 

 valves may be renewed in the 

 same manner, or they may be 

 repaired by grinding. Fine 

 spS?' J 9 um P A ^ a a'a y s P h e a f g , b t a j r o e r! ** with oil is placed be- 



Note the plunger cylinder and the tWCCn the Valve and its Seat 

 large air chamber. 



and the valve turned back and 



forth in a rotative manner until the surfaces are ground 

 to a perfect fit. 



The plunger type of cylinder has many advantages. It is 

 of easy access for repairs, and it is easy to determine whether 

 or not the plunger is leaking. The packing is often placed 

 between two disks, which cause the packing to expand as 

 they are screwed together on the plunger rod. The pump 

 with the stuffing box and the inside plunger is to be guarded 

 against. Of course, double-acting pumps must have stuff- 



