How do I operate this tensioner?

[Mark Gibney]

How do I operate this tensioner to tighten the V-belts?
It's on a jointer.

478245 478246

I fiddled around with it but I couldn't move the motor in any direction.
All opinions welcome.
thanks, Mark

[Maurice Mcmurry]

It looks like the weight of the motor should provide adequate tension. The threaded rod and nuts look new. They seem to be keeping the motor from hanging. New belts or loosening the nuts on the threaded rod may be in order.

[Paul F Franklin]

Looks to me like the bolt extends through the casting. If so, you'd turn the top nut to adjust, then use the bottom nut to lock it in place. But it looks like it might be at the end of its range; might be time for new belts.

[Maurice Mcmurry]

I got zoomed in, It appears you may be at the limit of adjustment. If the shiny threaded rod (bolt) can be removed gravity might do the trick?

[johnny means]

Can you get to the top of the bolt? Bolts not meant to turn, so the nut up top has to adjust tension. What happens when you tighten the top nut to the casting?

[Brian Runau]

I got zoomed in, It appears you may be at the limit of adjustment. If the shiny threaded rod (bolt) can be removed gravity might do the trick?
2nd vote for this. Bolt is bottom up so top but adjusts to increase or decrease downward pressure. Old design, but should work when adjusted. You may need to replace the bolt with a slightly longer one. Adjust the very top nut to properly tension belts and use 2nd nut near top to lock it in so it won't vibrate loose. Brian

[mike calabrese]

I agree with the previous posters looks like you are out of travel or another way to look at it the belts are wrong ...too long.
It looks like the motor mounting platen is on a pivot , the shaft that is seen to the far right in the pic.
The long bolt or rod with the double nut arrangement in the jacking screw not so much to push the motor down, gravity will do that but designed to keep the motor from rising up thus un-tensioning the belts. Another clue is how the jacking bolt is perpendicular to the attachment point above and threaded into a second pivot point on the motor plate.
Your problem I believe is the belts are wrong, too long, as it looks like there is considerable travel available to pull the motor up which would allow a shorter belt and to allow gravity plus the jacking bolt to properly tension the belts.
It is the classic question is the glass half full or half empty...no it is the wrong size glass !:D
mike calabrese

[Mark Gibney]

Thanks for the input everyone.
However, when I tighten the upper nut against the casing, it just jams in place.
At that point nothing moves - the threaded rod doesn't turn. The platen stays where it is.

I will replace the belts for sure, these ones are old.

I'll let you know what I find out today.

[Tom M King]

Something about the motor mount, which is hinged, is bottoming out.

[Mark Gibney]

Let this be a cautionary tale to us all not to look into a problem at the end of a long day when you're tired and hungry, and completely miss the answer.

I took a look at it the morning after, and how the mechanism works is obvious and simple - the threaded rod has nuts on both sides of the casing, and you simply loosen / tighten each set of nuts to lengthen / shorten the rod.
It also has a bolt on the hinge that was tightened down hard.

Thanks for all your helpful replies, and my apologies for the wild goose chase!

[Maurice Mcmurry]

Twin belts, it must be a hefty unit. Is that Grizzly green?

[Mark Gibney]

Not a Grizzly, it's an older EMA.

[David Buchhauser]

Thanks for the input everyone.
However, when I tighten the upper nut against the casing, it just jams in place.
At that point nothing moves - the threaded rod doesn't turn. The platen stays where it is.

I will replace the belts for sure, these ones are old.



I'll let you know what I find out today.

I believe you need to loosen the top nut and tighten the bottom nut if you are attempting to tighten the belts. Loosening the top nut will allow the threaded rod to slide down thru the casting so you can tighten the bottom nut (the one right under the casting) to adjust the belts. If the threaded rod is not long enough, you can easily replace it with a longer piece of "all thread" threaded rod.
David