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When should I use a rotary versus linear tensioner?

A linear moves in a straight line and a rotary swings in an arc. Sometimes mounting location, drive configuration, etc. will not permit the use of one versus the other. The application should be closely reviewed to determine which tensioner is best suited. We can help you determine which is best for your application - just give us a call.

Which tensioner is the best one for my application?

Generally, the rotary style is primarily used on belt drives, although it can also be used with chain drives. The CT linear tensioner with the UHMW head is the most popular on chain drives.

Can I use the tensioner/idler on the backside of a belt?

Yes. Although a backside idler increases wrap angle and power transmission capacity, it does introduce a reverse or back bend in the belt that will shorten belt life. Consult with the belt manufacturer for minimum pulley diameter and location.

My drive reverses — where do I locate the tensioner/idler?

Spring-loaded tensioners should never be used on reversing drives. If they are, when the drive reverses the slack side becomes the tight side and vice versa. A tensioner designed for the slack side would then have inadequate spring force to maintain belt tension.

How do I determine what size tensioner/idler I need for my belt drive?

Selection of the proper size tensioner can be made using the guidelines specified in this catalog. Consult with the belt manufacturer, who can determine the right amount of spring force based on the application and drive parameters.

I have some contaminants in my application — will they have any effect on the tensioner?

Our tensioners are made from glass filled nylon or aluminum. Although many chemicals/oils will not affect them, they are not resistant to all. Contact Fenner Drives application engineering group with the contaminants present and we'll make a recommendation.

On my belt or chain drive, where should the tensioner/idler be located?

Always install the tensioner/idler on the slack side of the drive.

Where is the best place on my V-belt drive to locate a tensioner/idler?

Preferably, a tensioner/idler should be located on the inside of the drive. Optimum placement would be where it provides nearly equal arc of contacts on both the driveR and driveN pulleys.

Where do I position the tensioner on my chain drive?

The tensioner should be located on the slack or sag side of the chain and outside the perimeter of the chain strand.

I am using chain other than standard ANSI roller chain. Can I get the UHMW head on a CT linear tensioner to match my chain?

Consult Fenner Drives application engineering group. In many instances we have been able to design and furnish a special UHMW head.

Do I need to periodically grease the springs?

In most cases, no. The springs are pre-lubricated at the factory and the unit is assembled. However, on occasion an application may dictate the need for re-lubrication. Contact Fenner Drives application engineering group. We may be able to design a tensioner with a fitting that will allow this.

Where should I position the tensioner in the chain span?

Unless a chain guide is being used, it should be located an equal distance from the driveR and driveN sprockets.

My chain drive appears to have excessive slack — will a tensioner help this problem?

Usually, under normal conditions chain slack should not exceed 4% of the span. For unusual conditions such as heavy loads, frequent starts/stops, etc. it should not exceed 2% of the span. Excessive chain slack usually occurs on drives with long spans. Typically a span greater than 50P (P= chain pitch) will require a tensioner.