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Renold Chain’s David Turner provides advice on when worn transmission chain sprockets need to be replaced.

Sprockets that have worn beyond a certain point will cause rapid chain wear and should be replaced as soon as possible, according to Turner.

He added that there are a number of visual checks that should be carried out to determine this.

Looking at the faces of the sprocket’s teeth will give an indication of the amount of wear that has occurred.

This will be seen as a polished worn strip, about the pitch circle diameter, on each of the teeth.

If the depth of the wear, X, has reached a value equal to 10 per cent of dimension Y, then the sprocket has reached the end of its life and needs to be replaced.

Low-cost, poor-quality sprockets on most industrial applications are a false economy, said Turner.

A good-quality sprocket should last through the life of several chains before there is significant wear.

When changing sprockets, it is a good time to check the alignment of both the sprockets and the shafts to which they are fitted.

Misaligned sprockets are another factor in premature chain wear.

The accurate alignment of shafts and sprocket tooth faces provides a uniform distribution of load across the entire chain width and contributes to achieving maximum drive life.

Turner recommends using a straight edge across the machined faces of the sprockets in several different positions, if possible, as a check against wobble.

Another tip is that a nylon, or similar line, is a good substitute for a straight edge, particularly for drive systems with long centre distances.

Should an end-wise float of shafts be present, the user should make due allowance so that sprocket alignment is correct at the mid position of float.

When alignment is correct within the closest practical limits, the user can drive the keys home and take a final check on sprocket alignment.

Those fitting a new chain at the same time should not forget to correctly lubricate it.

The lubrication that is on the chain when it comes out of the box is only sufficient to prevent corrosion and aid initial bedding-in.

Founded in 1879 by Hans Renold, the Swiss engineer who invented the bush roller chain, Renold is a specialist global manufacturer of power transmission products and systems. Wherever there is mechanical movement Renold’s products can be found either at the heart of the system or working quietly in the background providing the precision, reliability and peace of mind that has become the hallmark of the brand. Renold’s innovative products and expertise benefit a divers range of sectors including manufacturing and process industry, marine propulsion, aerospace, specialist vehicles, mass transportation, mining, quarrying, theme park rides and people moving applications where reliability and safety are critical.

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