36 



CEMENTS, LIMES, AND PLASTERS. 



The Stedman disintegrator (Fig. 7) is composed essentially of four 

 concentrically placed cages, formed of steel bars. Of these cages, the 

 first and third revolve in one direction, the second and fourth in the 

 opposite. The material to be crushed is fed into a hopper which dis- 

 charges it at the center of the cages. The gypsum lumps are struck 



FIG. 7. Stedman disintegrator, 50 -inch, heavy pattern; open and slid apart. 



by the bars of the inner cage, and thrown outward at high velocity. 

 The bars of the second cage, revolving in the opposite direction, strike 

 them with a blow of double force, and this operation is repeated by the 

 bars of the third and fourth cages in succession. 



TABLE 5. 

 SIZES, CAPACITY, ETC., OF STEDMAN DISINTEGRATORS. 



