Plain Pulley Lagging Should be avoided
Increased Costs, Risks and Failure Occurrences
We strongly recommend avoiding the use of Plain Pulley Lagging in almost all Conveyor Belt Systems. There is no cost benefit – a modern Pulley Lagging manufacturer will likely charge more as it requires more rubber in the compression moulding process than Pulley Lagging with a tread pattern – and the risks introduced are high and often result in costly failures and downtime. This includes Non-Drive Pulleys.
The only potential exceptions to this recommendation of ours are light duty, indoor, clean applications such as those found in consumer goods packaging plants. But even here, we still wouldn’t recommend it if it isn’t absolutely necessary for some other reason. The specification of Plain Lagging by engineers persists because of a lack of understanding of the importance of stable traction - we have heard the suggestion that "float" is a characteristic that is desirable, but this suggests a lack of understanding of how friction and traction actually work, and what one is referring to as float is in fact unstable traction.
A tread pattern removes foreign matter such as mud and moisture from the interface between the Pulley Lagging and the Conveyor Belt:
The removal of foreign matter is critical for two main reasons:
- Contact between the Conveyor Belt and Pulley Lagging is maintained. This ensures traction in all conditions.
- The effective outer dimensions and cylindrical shape of the Pulley are more likely to be maintained. I.e. a clump of mud is less likely to become compacted on to the Pulley Lagging that would create an uneven, misshapen cylindrical shape.
The risks are detailed in the following table.
RISK | IMPACT | CONSEQUENCES | ||
|---|---|---|---|---|
Hydroplaning | Loss of Belt-Tracking. Belt-tracking and alignment relies to an extent on traction. A loss of traction can cause the belt to run off to one side. Uneven loading of the Conveyor Belt, even momentarily, can exacerbate this issue and cause expensive failures. |
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Hydroplaning | Unreliable Belt-Training and Commissioning. If the Conveyor Belt is commissioned in dry conditions, it can be expected to track differently in wet conditions, and vice versa. Additionally, Plain Pulley Lagging replaced on site is almost exclusively replaced with Pulley Lagging with a Tread Pattern. |
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Hydroplaning | A fluctuating difference in speed between the Pulley Lagging surface and Conveyor Belt. |
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Entrapment of Foreign Matter on Pulley Lagging | Misshapen Non-Cylindrical “Pulley Surface”. The Conveyor Belt will no longer be running on a cylindrical surface. This will affect the forces that the Conveyor Belt experiences, damaging the Conveyor Belt Carcass and causing Belt-Tracking and Alignment issues. |
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Entrapment of Foreign Matter on Pulley Lagging | High Shear and Compressive Forces Experienced by the Pulley Lagging. The trapped material has no route out due to a lack of grooves. The shear forces seen by the Pulley Lagging are high and can cause the Pulley Lagging to tear. Torn Pulley Lagging introduces all risks mentioned previously. |
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Unforeseen failures of a Conveyor Belt System can often be traced back to the decision to make use of Plain Pulley Lagging. Plain Pulley Lagging is a legacy product that exists because outdated methods of manufacturing Pulley Lagging involve hand-cutting the grooves into the Pulley Lagging – this process is slow and costly. Fortunately, the hand-cutting of grooves is no longer a necessity and methods of manufacturing more robust and reliable Pulley Lagging products with a Tread Pattern exist and are available in both Hot Vulcanising and Cold Bonding processes, including by ABEAR Industrial.