V Belt tensioner

37chief · May 22, 2019

My flail mower belt tensioner is on what I call the power side of the belts. When the machine was designed, it has been like this since. Should the tensioner have been on the back side of the belts, or what I call the slack side? The belts seam to run on the hot side. Maybe this is normal? Stan

Janicholson · May 22, 2019

Best practices in design would put the tensioner on the slack side preferably on the inside of the run so it would be a V style idler, not flat. This allows the tensioner to be under the least strain. V belts run pretty hot because they loose a solid % of there total power to friction. Jim

flying belgian · May 22, 2019

I just never heard of that. Are you sure the belt is threaded right?

redforlife · May 22, 2019

Are you sure you know what direction the belt runs? And it's not running the opposite direction as to what you are thinking.

Considering the power pulley is the starting point, the tensioner should be the last puley the belt goes around before it gets back to the power supply pulley. If there is an idler pulley, it may be that that pulley is between the tensioner and power pulley. But if so, that should be the only one.

If it is the way your thinking, tension pulley right off the power pulley in the direction of belt travel, then this is clearly a very bad engineering situation. Wich wouldnt suppries me. Manufacturers and engineers only care about one thing these days. Just getting something on the market, and they don't care what happens after that.

redforlife · May 22, 2019

Thinking I might of misundertood your post in my original reply. If your talking about the belt itself running around the tensioner pulley with it's backside (flat side) against the pulley, instead of the V side like the other pulleys, then this is pretty common. There is nothing to be powered by tensioner, and it doesn't need the extra friction of the V side of the belt. If that's what your talking about. But it still should be about the last pulley it goes over before getting back to the power pulley.

jeffcat · May 22, 2019

This is going to be some discord ready replys. I would say the SLACK side just going AWAY from the power pullet would get the spring loaded idler. Not carved in stone. Some lawn mower decks that idler is about 1/2 way through the belts path. An idler on the Draw side is bad news. Any variation in the amount of power required will have the idler bouncing all over the place. See if your idler is where the belt is just leaving the power pulley. I think is best . If you have a chain going around you REALLY want it on the slack side. It will whip if incorrect.

Steve@Advance · May 22, 2019

Ideally, the tensioner should be on the slack side of the belt, and on the flat side of the belt in order to get as much pulley contact as possible.

Possibly a non-spring loaded tensioner would work on the power side, but it would need to be kept very tight, otherwise it would encourage slipping.

Russ from MN · May 22, 2019

I agree, it's best to have the tensioner on the slack side, close to the driven sheave to increase wrap, less slippage that way. I agree with Jim's point about not having a flat pulley on the backside, but that's the way most of them are, and they work OK if you use a Kevlar belt.

V Belt tensioner

37chief

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Janicholson

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flying belgian

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redforlife

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redforlife

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jeffcat

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Steve@Advance

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Russ from MN

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