The last thirty years have seen numerous innovations in conveyor technology that have brought greater safety and efficiency. However, change in this field has not always been necessarily for the better.
One innovation is the introduction of sprockets with an even number of teeth which were designed to offer customers a greater choice when designing chain conveyor systems.
However, sprockets with an even number of teeth are not generally recommended by experienced technical engineers.
If a sprocket has an even number of teeth, the same tooth will be engaged by the same rollers on each rotation, leading to uneven wear and decreased service life.
A similar result will occur if the number of teeth in the smaller sprocket is a divisor of the number of pitches on the conveyor chain.
Choosing a sprocket with an odd number of teeth will offer you at least double the service life.
Double pitch sprockets, while often overlooked nowadays, are ideal for saving on space and have a longer wear life than standard sprockets.
Suitable for long pitch chain, double pitch sprockets possess more teeth than a standard sprocket of the same pitch circle diameter and they distribute wear evenly across the teeth.
Many of today’s conveyors include electronic load monitoring in the control system. While this is a useful safety feature, technical engineers recommend that these are used in conjunction with shear pin sprockets.
Electronic sensing is ideal where there is a slow increase in load (due to damaged bearings or dirt contamination) as there is time to stop the drive before any damage can occur.
In the case of a misfeed or mechanical breakage, where the load increase is sudden, the sensor will not automatically break the connection between the motor and the driven load – which can cause extensive damage to the conveyor chain and its attachments. This is why a shear pin sprocket is also needed.
Shear pin sprockets may be more expensive than standard sprockets at the outset, but they will limit downtime and save on replacement costs. And if a conveyor becomes overloaded and potentially dangerous, the shear pin will break and stop the conveyor, thus limiting damage.
Once the load or obstruction has been cleared, only the shear pin needs to be replaced which means the conveyor can quickly start moving again.
Older types of sprocket are often forgotten, but they can offer considerable advantages including longer service life, minimised damage in the event of a conveyor breakdown and reduced replacement costs.