Lesson 1/Learning Event 2
DUAL ROLL CRUSHERS
Function and Operation. Roll crushers are used exclusively in the military supply system to accomplish the
intermediate stage of reduction of rock (Figure 2).
FIGURE 2. DUAL ROLL CRUSHER
All roll crushers in the Army are dual rolls varying from 24 inches to 54 inches in diameter.
The crusher assembly consists essentially of a set of rolls which revolve toward each other at constant rim speed.
Stone particles are reduced in size as they are drawn between the two rolls. Product setting is determined by the
spacing between the rolls. It is necessary to set the opening between the rolls slightly closer than the top product
size required. With two coarse corrugated shells, the tip to tip setting will produce a product larger than two
smooth shells set at the same distance.
Production Consideration. Generally speaking, the same variable factors discussed for jaw crushers will affect
the production of roll crushers. By com-