An impact roller is one of the support and guidance elements used on flat and trough conveyor belts systems. The specific function of an impact roller is to lend the conveyor additional support at transfer and loading points where the belt is subjected to considerable impact stress. Although similar in general design to other roller elements, the impact roller features a central member of reduced diameter and a thicker, grooved rubber lining. The thicker lining and grooved surface offer superior resistance when compared to conventional rollers. Impact rollers may be arranged in standard, fixed trough frames or suspended in garland arrangements depending on belt configurations.
Conveyor belts utilize large numbers of rollers along the non-load surface of the belt. These roller arrangements ensure that the belt is supported and runs straight. They may also be configured to allow the belt to deviate laterally around bends while maintaining an adequate load area. Impact rollers serve the specific purpose of helping to absorb the intense impact on the belt at loading and transfer points.
Conveyors transporting large aggregates such as raw coal and iron ore are constantly battered at the point where the belt is loaded or where one belt discharges onto another. These repeated impacts can severely wear a conveyor and eventually lead to belt failure. Rows of impact rollers are placed at these points in such a way that they cushion much of the force and prevent accelerated wear. The row frequency of impact roller sets at a load point is typically higher than normal guide rollers along its length.
Conventional idler and guide rollers would not afford the same degree of protection as the impact roller as they usually feature large diameter shells with thin rubber lagging. Impact rollers differ in design in that they have a far smaller core shell and a much thicker rubber lining. This lining is normally designed as a set of concentric rings which form a grooved surface to the roller. The typical impact roller features an inner core diameter of approximately 3.5 inches (90 mm) and a total diameter of 6 inches (152 mm).
The roller spindles are flattened in the same fashion as normal idlers, thus allowing the roller to be slotted into standard fixed frames. This lends logistic flexibility to impact rollers as they may be used on standard trough frames. The rollers can also be suspended on garland style mounts if the belt configuration requires it. The typical spacing of impact rollers seldom exceeds 17 inches (450 mm) to allow for the maximum amount of support for the belt.