These are designed to have different functions. Each function determines the design of the idler but the actual shapes of carrying and return sets generally remain the same.

Impact Carrying Troughing Type Idler:

Their function is to ensure maximum belt protection for the optimum service life. Impact idlers are used at the loading points where bulk material falling from height onto the belt could cause damage to it. Impact sets are equipped with rubber-lagged rollers with a number of rubber rings of appropriate thickness and resistance. These are designed for use in places where material is falling from a height (hoppers) onto conveyors fitted with carrying Troughing idler sets. Also it has very small spacing between two sets.

Impact Carrying Garland Type Idler:

These are designed for use in places where material is falling from a height (hoppers) on to conveyors fitted with garland sets.

Carrying or return training idler sets :

Carrying or return training idler sets assist in keeping the conveyor belt centred on the conveyor when temporary or transient conditions could result in belt misalignment. Two small side rollers attached vertically to the base frame provide for self-alignment of the belt. Training sets are generally spaced 30 m apart and not within 15 m of the head or tail pulley.

Centring Carrying Troughing or Carrying Vee idlers:

These idlers are used for supporting the carrying belt they have a centring effect caused by a slight incline of the axes of the side rollers (approx. 2°). They have the same function as training idlers but they are used on smaller dimension belts (for belt lengths up to 100 m). If they are used they should be fitted along the whole length of the conveyor.

Self-cleaning return idler type:

Several types are available Vee, flat and garland sets. Disc and spiral rollers are used. Disc rollers are used where sticky materials adhere to the belt, in a corrosive environment or where abrasive wear is a problem. These idlers can be used for belt travel in either direction. Compacted end discs are standard. Spiral rollers are used under the same conditions as disc rollers. Their unique construction minimises belt fleet and damage to the return belt due to material build-up on the idler rollers. Spiral roller idlers can only be used for belt travel in one direction.