PUMPING MACHINERY 269 



The stuffing-box tube is nothing more nor less than an 

 auxiliary piston fitted with the regular leathers. The 

 tube is always made of brass, and does not need attention 

 as often as the regular stuffing box. 



381. Pump cylinders. Three classes of pump cylin- 

 ders are found upon the market: Iron, brass-lined, and 

 brass-body. Iron cylinders are used mostly in shallow 

 wells. Brass-lined and brass-body cylinders are the 

 most desirable, as they work very smoothly and will not 

 corrode in the least. Iron cylinders are often galvanized 

 to prevent rusting. Brass-body cylinders have the cylin- 

 drical portion between the caps made entirely of brass. 

 Brass cylinders are easily damaged by being dented, and 

 when so damaged cannot be repaired to good advantage. 

 Brass being a soft metal, some difficulty is encountered 

 in making a good connection between the cylinder and 

 the caps by screw threads. In order to strengthen the 

 brass-body cylinder at this point, the caps are often fitted 

 on the cylinder by rods at the sides. 



Cylinders to be used inside of tubular or drilled wells 

 are made with flush caps to enable a larger cylinder to be 

 put into the well. 



382. Valves. The valves of a pump are a very vital 

 part. Most valves are made of iron in the piston and 

 leather in the cylinder cap. Brass often makes a better 

 valve than iron, as it will not corrode. The valve com- 

 monly used is known as a poppet valve, and may have 

 one or three prongs. The single-pronged valve is not 

 interfered with by sand to the same extent as the three- 

 pronged. Ball valves are used in deep-well pumps, but it 

 is very difficult to keep these valves tight. Various ma- 

 terials are used out of which to make the valve seats. 

 One large manufacturer manufactures valve seats of glass 

 and makes many claims for their superiority. 



