There are two basic types of roller crushers : two-roller and single-roller. The working principle is that the ore is fed from the upper part, and the relatively rotating roller is crushed by the frictional force into the crushing chamber to be crushed, and the broken ore is discharged from the two rollers under the action of gravity. The pressure of the spring 6 is sufficient to balance the pressure generated between the two rolls during normal crushing. If a non-crushed material falls into the crushing chamber, the spring 6 is compressed and pushed away by the movable bearing 5 to move backward. At this time, the gap between the two rolls is increased, and the non-crushed material can pass without damaging other components. After the non-crushed material is discharged, the gap between the two rolls can be maintained at its original size by the restoring force of the spring, and the crushing work is continued. The size of the discharge gap can be adjusted by increasing or decreasing the gasket behind the roller bearing. Automotive Grease,Car Grease,Forging Machinery Grease,High Temperature Gear Grease PUYANG XINYE SPECIAL LUBRICATING OIL AND GREASE CO.,LTD , https://www.xinyelubricant.com
The working mechanism of the two-roller crusher is two cylindrical rollers, as shown in the figure below. The roller 2 is supported by a fixed bearing 4, and the roller 1 is supported by a movable bearing 5. The rotation of the two rollers can be driven by the motor alone or by an electric motor (transmitted through the sun shaft) and rotated in opposite directions. 
The working mechanism of the single roll crusher consists of a rotating roller and a fixed jaw. So it is also called a roller crusher.
The specification of the roller crusher is indicated by the diameter D of the roller and its length L.
Roller crusher is an old-fashioned crushing equipment, but it is still used to deal with brittleness and viscosity due to its simple structure, compactness, light weight, reliable work, low price, uniform product size and low pulverization. sized clay beneficiation plant material containing (mainly gravity concentrator), as finely divided purposes. However, the biggest disadvantage of this type of crusher is that it cannot handle hard ore, and the productivity is very low, and the roll skin is easily worn.