While electronic load monitoring systems have helped to reduce conveyor malfunctions, unplanned and costly conveyor downtime is still an issue that plant engineers have to contend with on a regular basis.
"Of course load monitoring systems are a useful safety feature but they should not be seen as a panacea for conveyor breakdown issues alone," says Peter Church, managing director of FB Chain Ltd – one of the leading manufacturers and suppliers of leaf chain, anchor bolts and chain sprockets to the materials handling industry.
He continues: "Electronic sensing is ideal where there is a slow increase in the conveyed load- as a result of damaged bearings or dirt contamination, for example. In such cases there is usually time to stop the drive system before any serious damage occurs.
"However, in instances where a mis-feed or some other form of mechanical breakage occurs and the load increase is sudden, the electronic sensor will not automatically break the connection between the motor and the driven load. In such cases, the damage to the conveyor chain and any attachments is likely to be extensive."
To help eliminate, or at least reduce, the damage that will be caused by a sudden increase in load, Peter Church advises that conveyor chains should be driven by shear pin sprockets.
If a conveyor becomes overloaded – and, therefore, potentially hazardous – a shear pin sprocket will automatically break and stop the conveyor. The load or obstruction that caused the overloading problem can then be cleared and only the shear pin needs to be replaced before the conveyor can start working again.
"Shear pin sprockets may be more expensive than standard sprockets but their use limits downtime and reduces the number of more costly conveyor parts that will need to be replaced in the event of a serious problem," says Peter Church.
"Specifying shear pin sprockets is a simple way of ‘designing in’ conveyor efficiency and the return on investment makes a compelling argument for using them," he adds.
FB Chain Ltd offer a range of shear pin and conventional sprockets that can be retrofitted to most brands of chain driven conveyor systems used in a wide range of industry sectors.