Chain and belt drives are such basic tools that it's hard to find machinery without them; one turns your washing machine drum and another the fan in your microwave; chain drives keep conveyor belts moving and the wheels of your bicycle. Their energy-efficiency is excellent, and maintenance requirements are simple and few.

Most problems arise because of stretching. Correct tension in drive belts and chains is important, but some degree of stretching is almost inevitable over the course of time. If drive trains are too tight, their efficiency declines while frictional heat and wear increases. If they become too loose, they begin to slip - with similar consequences.

Some machinery is designed for tension adjustment by other means, such as by changing the distance between drive shafts. Chain tensioners and V belt tensioners are usually a more convenient means of taking up slack and maintaining tension within the optimal range. Tensioners may be manually adjusted or automatic.

Chain tensioners and V belt tensioners can often be added to drive trains not originally equipped with them, but it's important to remember that the pitches of cogged systems and chain-links must match within a range of tolerance. Different profiles of cog teeth and belt channels afford different degrees of tolerance, so tensioners are only helpful within these limits.

Chain slack should never exceed 4% of the span, or 2% with heavy loads. A number of chain tensioning tools and V belt tensioning tools are available to ensure correct tension.

Automatic Tensioners

Automatic tensioners also make it much simpler to set up machinery, reducing the need for exact belt lengths or shaft separations, and eliminating the risk of over or under-tensioning. Typically, these consist of a spring-actuated idler. In rotary tensioners this acts through a lever arm, and in linear tensioners it resides on the end of a spring-loaded shaft.

Some belt and chain tensioners are fixed in place, while others can be floating or positioned flexibly. The best place for tensioners on belt drives is usually inside of the slack side. If you are uncertain about your mounting options, Simply Bearings are happy to offer guidance.

Other Benefits

Tensioners help eliminate the risks of chain whip. Most cyclists are familiar with this: gear changes cause a sudden discontinuity in the length of the drive route, which can either unrail the chain or cause a sudden tug on the rear mechanism. Tension wheels rapidly absorb these changes. The same occurs in machinery that encounters momentum changes for other reasons - such as a bandsaw cutting through lumber or a vehicle hitting a pot-hole.

Spring-loaded tensioners are rarely suitable for reversing drives - again, think of the problems this causes on a bicycle.

If you can't identify the tensioners, chain tensioning tools or V belt tensioning tools you need, Simply Bearings are happy to locate them for you.