Manufacture of Cement Pipe 



83 



of sizes in the regular equipment is from 14 inches to 36 inches 

 diameter. The lengths used are 24, 30, and 36 inches. 



A view of the National pipe machine is sht)\vn in Fig. 9. The 

 heavy steel frame is seen to carry a short main shaft (8) driven by 

 pulley, and a long countershaft (6) at the top driven by chain. The 

 countershaft operates two vertical tampers (4), which play up and 

 down like trip hammers, alternately striking tamping blows, 350 per 



Fig. 9. — The National pipe machine. 



minute each, with a force of 75 pounds. The tampers begin at the 

 bottom and work up with the concrete. The table (2) on which the 

 forms are set is rotated, bringing all parts of the tile under the 

 tampers. The mortar or concrete is elevated (1) and dropped into 

 the mold as in the other machines. Five horsepower is said to be 

 required on the belt and a 10-horsepower gasoline engine is ad- 

 visable. 



