How would you solve this problem. Mower belts rubbing.

[4570Man]

I replaced the center pulley on my mower with a double pulley and got rid of the stacked center pulley which reduced the clearance. Now the belts rub against each other. Even before swapping the pulley the belts rubbed against each other evident by the abnormal wear on the belt. I’m thinking some rollers to hold up the brown belt would help but the roller of such small diameter would be spinning at a smoking fast rpm and probably wouldn’t last long. Any other ideas? ATTACH]594984[/ATTACH]

 

[4570Man]

If my math and assumptions are right the little roller would be going 11,650 rpm to match the FPM of the belt.

 

[CADplans]

Simply raise the double pulley until the brown belt clears,,
The belts can run out of alignment slightly,,, much better than having a bunch of rollers etc,,, pushing the belts around,,,:confused2:

 

[4570Man]

I already tried raising it about 1/4” to no avail. I may try raising it more. But my hopes aren’t good for that approach. But the more I think about the high rpm of the rollers I don’t think that’ll work either.

 

[rangerfredbob]

Add an idler pulley on the brown belt pushing it slightly up in the middle, V belts can take some misalignment without issue, something like THIS, just put a little off center pressure on the idler but space it up enough for the two belts to clear eachother. I just searched for V belt idler, here's another option. All it would take is one of those pulleys, a single hole in the deck a bolt and possibly some washers to get the right spacing...

 

[chim]

If the bottom sheave on that double is in alignment with the idler assembly to the right, how can the belts rub? It looks like you either have the double mounted too low or the shafts aren't all perfectly vertical.

I'm guessing that idler has a spring attached to the other end of that flat bar. Since the flat bar is on the top of the idler, the spring could want to lift the idler out of alignment if there's any play. Any chance the flat bar is bent or loose, making it higher on the end where the spring attaches? Any play in the bar / mounting? Bad bearings in the idler? It wouldn't take much. I just measured a double sheave from a deck I'm working on and the belts are only on 3/4" centers.

There may be something I'm not seeing - and that might be why the manufacturer used two sheaves.

 

[4570Man]

I had all the deck pulleys vertical until I raised it. The drive pulley doesn’t move when you raise and lower the deck so it doesn’t maintain the same height.

 

[chim]

OK, I was picturing the setups on my decks. They are PTO driven, so all the pulleys are in fixed positions.

From what you're saying, the drive pulley is on the tractor and is higher or lower (in relation to the other pulleys) as the deck is lowered or raised. Does the rubbing still happen when the deck is lowered? Could you raise the drive pulley on its shaft?

 

[Ford850]

Why not go back to the original design with a stacked center pully?

 

[chim]

Why not go back to the original design with a stacked center pully?

I wondered about that till I re-read the part where he said the belts rubbed before the swap. Right now I'm leaning towards believing the drive pulley is too low on its shaft. It's always a challenge to discuss a situation that's in a different ZIP code, even with pictures.

 

[4570Man]

Why not go back to the original design with a stacked center pully?

Well I could but I’d have to buy 2 more pulleys. I swapped because the drive pulley was worn out and another was busted so swapping to the double fixed those issues. Even if I did swap it back to stacked pulleys it would only help the problem not fix it. The motor is a horizontal shaft diesel with a non adjustable set of idlers to divert the belt to vertical.

 

[SPYDERLK]

I replaced the center pulley on my mower with a double pulley and got rid of the stacked center pulley which reduced the clearance. Now the belts rub against each other. Even before swapping the pulley the belts rubbed against each other evident by the abnormal wear on the belt. I’m thinking some rollers to hold up the brown belt would help but the roller of such small diameter would be spinning at a smoking fast rpm and probably wouldn’t last long. Any other ideas? ATTACH]594984[/ATTACH]View attachment 594985View attachment 594986

Cant you cant the tensioner pulley to lower that belt segment?

 

[rangerfredbob]

I had misunderstood what the top belt was before... if you can lower the tensioner pulley by about 1/4" that should help I believe

 

[4570Man]

That might be a possibility but evident by the rubber burns on the deck the lower belt is already slapping the deck.

 

[4570Man]

I’ve adjusted on it some more and raising the pulley an inch makes enough clearance but then it makes the lower belt rub tensioner bracket. There’s no position to eliminate both problems. Tilting the tensioner bracket makes no difference because it doesn’t control the second part of the lower belt. I guess I’ll have no choice to go with the roller idea which I don’t like or put separate pulleys back on which is probably what I’ll do.

 

[SPYDERLK]

I致e adjusted on it some more and raising the pulley an inch makes enough clearance but then it makes the lower belt rub tensioner bracket. There痴 no position to eliminate both problems. Tilting the tensioner bracket makes no difference because it doesn稚 control the second part of the lower belt. I guess I値l have no choice to go with the roller idea which I don稚 like or put separate pulleys back on which is probably what I値l do. View attachment 595093

Referencing this picture:

You have the tensioner bracket pivoting on a stud and the tensioner pulley pivoting on a bolt in the bracket. I think the bracket should be bent downward as closely as possible on the righthand side of the pulley pivot. This would position the side of the bracket, where the spring is, lower than now, and the resulting downward angle would cause the exit side of the pully - and thus the belt - to be lower.​

You probably will have to space the pulley downward a little so it doesnt rub on the bracket right side due to the new aspect caused by the bend.

 

[4570Man]

Both belts cross the other belt twice forming a square. The tensioner has no affect on the back section of the lower belt and it also rubs.

 

[big bubba]

simple obvious question. have you checked the idler pulleys for bearing wear? experienced misalignment/ belt rubbing when idler bearings were shot. don't understand why idler pulleys don't have grease zerks like the spindle drives.
sorry for stating the obvious, am sure you've checked

 

[4570Man]

The idler is good. The idler can’t completely fix or cause the problem anyway.

 

[Dave M7040]

From what I see in the photos and from my experience, the idler pulley is not running flat.

If the idler pivot has any wear, then the spring and the belt cause the idler to tilt off horizontal.

Many idlers use a shoulder washer. .

I do not see one on yours but this pivot, however designed, is the weak point allowing the belt to run off the center on the idler which is what I think I see on yours.

On one mower, I used a spindle assembly upside down to have a pivot for the idler which had no up and down flex.

Dave M7040