Reducing Belt Conveyor Transfer Impact Energy using a Dynamic Idler

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Reducing Belt Conveyor Transfer Impact Energy using a Dynamic Idler

Written by Portelli, C.T. – edited by mhd on 18. Oct. 2019

2.3 Grizzly Screen

A grizzly screen allows finer material through to the conveyor system load point prior to the larger lumps such that a layer of fine material can act as a cushion to the lump impact.

Advantages	Disadvantages
Uses the conveyed product to take some of the impact force. Low cost implementation.	May slow the throughput and increase the risk of blockages. Given the open nature of the transfer with lumps falling onto the lighter product stream, dust may become an issue.

Fig. 8: Grizzly Loading Chute shown by Conveyor Equipment Manufacturers Association [2].

2.4 Impact Belt Support Systems (Cradles)

An impact belt support system utilises low friction topped impact bars to fully ‘cradle’ the belt to keep the belt line as consistent as possible and using the dynamic nature of the impact bar core (usually low durometer rubber) to absorb impact force.

Advantages	Disadvantages
Keeps the belt line consistent. An elimination of belt sag between roller frames allows for better skirting contact with the belt, resulting is less spillage. Low maintenance due to a lack of moving parts and a high strength retractable frame. Low cost implementation.	Even with the dynamic nature of the low durometer rubber core of an impact bar, the cradle is still close to a static system, resulting in high impact forces being transferred to the belt. Though a low friction surface, the UHMWPE (Ultra High Molecular Weight Polyethylene) tops of the impact bars increase friction over rollers which requires more drive power and are generally limited to a belt speed of 4m/s. This can be reduced using impact rollers in the centre of the cradle (Fig. 10) use of high speed slider rails (Fig. 12) and providing correctly located lead in and lead out rollers (Fig. 11).

Advantages

Disadvantages

Keeps the belt line consistent. An elimination of belt sag between roller frames allows for better skirting contact with the belt, resulting is less spillage.
Low maintenance due to a lack of moving parts and a high strength retractable frame.
Low cost implementation.

Even with the dynamic nature of the low durometer rubber core of an impact bar, the cradle is still close to a static system, resulting in high impact forces being transferred to the belt.
Though a low friction surface, the UHMWPE (Ultra High Molecular Weight Polyethylene) tops of the impact bars increase friction over rollers which requires more drive power and are generally limited to a belt speed of 4m/s. This can be reduced using impact rollers in the centre of the cradle (Fig. 10) use of high speed slider rails (Fig. 12) and providing correctly located lead in and lead out rollers (Fig. 11).

Fig. 10: K-Shield Combi Cradle employs (K-Shield Retractable) impact rollers in the centre to reduce friction.

Fig. 11: A correctly placed lead in/out idler prevents unnecessary wear and friction.

Fig. 12: High Speed Slider Rails incorporated into a high capacity system with catenary idlers.

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