PTO belt jumping off

[chadkiser 0]

I'm having a problem getting the PTO belt to my 48" mower to stay on the pulley at the PTO. This is on my 712H. The inner pulley groove seems to be out of line with the 2 pulleys that are connected to the tensioning lever, the belt jumps into the outer pulley groove and stops turning. What do I need to do to get the belt in line or to stop from jumping grooves?

[MPH 12]

I'm not quite getting the picture, you talking from the BGB to the center PTO or from the center PTO to the deck?

[chadkiser 0]

quote:

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Originally posted by MPH
I'm not quite getting the picture, you talking from the BGB to the center PTO or from the center PTO to the deck?

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It's the belt from the center PTO to the deck.

[MPH 12]

As that belt does a 90 degree twist, if it's a bit too long, thus a bit loose is about all I can think of would make it jump off.

[Al 6]

Hi, I would suspect that the pivot shaft on the idler pivot assy. is worn,and the hole in the frame side plate is ovaled out. This lets the pulleys aim in the wrong direction. I have fixed a number of these. Since the pulleys are pulling up and forward on the left side tractor frame plate, they wear the top and front of the pivot shaft and the hole in the frame. Get a new pivot arm and shaft. Next on the outside of the frame take a disk grinder and grind into the welds on the piece of steel welded to the frame side plate. Take an air chisel and cut this piece off. Grind the frame plate flat and make a new piece the same thickness as the one you removed. Drill a hole in it and put the shaft of the new pivot arm through it and locate at the lowest and rear most spot of the "ovaled" hole in the tractor left side frame plate and weld it on. This will return the idler assembly to the original location and will probably fix all belt roll over and jump off problems. One other thing. Check for the proper spacers and washers behing the idler pulleys. Some times adding a washer can also help. My 2 cents worth and its free, value accordingly. Al Eden

[chadkiser 0]

Thanks MPH & Al, I think I'll try a new belt first. I can pick one up at lunch today and hopefully be mowing this evening. If that doesn't work I'll start looking into what you said Al. Thanks again.

[HubbardRA 19]

I had a similar problem when I first put the 48 inch mower on my 716H. I didn't have a factory belt, so I bought the closest commercial belt I could find. It ate two in a month. I started looking at the idlers and saw that things were not lining up. The idlers were pulled up too far. I installed a slightly smaller idler to replace the backside idler. This allowed the assembly to swing down lower and put the belt back in alignment. The new belt that I installed at that time is still working two years later. I guess you could say that this one has been converted to use the commercially available belts, instead of the factory belts. There is a fraction of an inch difference in the belts.

[chadkiser 0]

What size belt are you using, 1/2x71 or 1/2x72? I'm using 1/2x72 and was considering swapping it out with a 1/2x71.

[Marty-MN 0]

Some hardware store belts have a smaller cross section (hight) making them more prone to jumping and rolling over

[slb04786 0]

Couple of things to check before you replace the belt. Check to make sure your new belt or the existing belt is tensioned properly by refering to the red/green gauge between the 2 pulleys on the tensioner. Secondly, did you have a snowblower mounted on your tractor this winter. If so you may need to move the flat idler pulley for a mower deck. I'm not sure if yours is so equiped but I have to move the pulley from one hole on the tensiner plate to another hole to get it to align the belt for the front mount snowblower and the mid mount mower deck. Just a couple of things that come to mind.

[chadkiser 0]

quote:

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Originally posted by slb04786
Couple of things to check before you replace the belt. Check to make sure your new belt or the existing belt is tensioned properly by refering to the red/green gauge between the 2 pulleys on the tensioner. Secondly, did you have a snowblower mounted on your tractor this winter. If so you may need to move the flat idler pulley for a mower deck. I'm not sure if yours is so equiped but I have to move the pulley from one hole on the tensiner plate to another hole to get it to align the belt for the front mount snowblower and the mid mount mower deck. Just a couple of things that come to mind.

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I'll check the holes on the tensioner plate. I just got this mower 2 weeks ago. I don't think there was ever a snowblower mounted on this tractor. I live in a part of North Carolina where we haven't had any snow in over 2 years.

[HubbardRA 19]

It is the 7100 series that has the two holes for the idler, not the 700 series. I think I am using the 71 now, because it was a little too tight before I changed the idler. (I really don't remember the actual sizes) The next larger belt was always too loose by my standards. The shorter belt pulled the idlers all the way up against the frame. I grabbed a smaller idler out of the garage and put it on. This let the idler assembly move down to where the belt, pulleys, and idlers were lined correctly. Worked fine ever since. I even swapped the belt and idler pulleys from the 716H to my 713S, and it still works good on that one. Did that after burning up the cone clutch on the 716H.

[chadkiser 0]

It was the belt, the one that I had on there was stretched. The stop on the idler bracket was up against the frame. With the new belt installed it's stretched tight with a large gap between the stop on the bracket and the frame. Thanks for everyone help.

[Killer_A-C 0]

It has been my experience if you use anything other than a Simplicity belt you are asking for trouble.We went threw several green belts before we realized it,Matt

[chadkiser 0]

OK it wasn't the belt. I just destroyed a factory belt in about an hours time. I'm thinking it's the idler pulleys. Can someone look at this page parts manual at the page marked 22 http://www.simplicitytechpubs.com/6767PRINT/PDF_files/TP_400_0236_00_SV_S.pdf What size are the 2 pulleys (items 26 & 32) supposed to be? I think someone in the past has changed item 32 to a smaller dia pulley. The reason I think it's smaller than the factory pulley is because the belt appears to be rubbing against item 26 when it's running. They had also removed item 33, should this part matter? Thanks

[MPH 12]

Looking at that picture got me wondering, when past owner removed the belt guide, part # 33, did they also remove part # 28 and 36, the spacers? Or maybe just # 36 throwing the two pulleies outta line with each other since you state the belt rubs on part # 26. This could throw the belt alienment off enough to be your problem I think. Don't have anything that new to look at so I'm just going off the parts pic. Matter of fact, just having part # 33 missing, guessing it might have been 1/8 -1/4" thick iron would throw the two pullies outta line some. Might try putting a couple washers on the bolt to equal the thickness of part # 33 if it came to MIA.

[UCD 14]

Here is a better diagram and a picture from the Allis Chalmers 700 manual. If pulley #25 rear idler was smaller and in the correct hole it could not touch pulley #23 front idler. If pulley #25 was an oversize pulley it is possible it could rub pulley # 25. I suspect the problem is that pulley #25 rear idler is in the wrong hole on the bracket. It is in the hole the tension spring is supposed to go in. (blue line) AS you can see in the bottom picture there is plenty of clearance between the two pulleys if mounted correctly and for the correct alignment all of the parts have to be there and in the correct place as in the top diagram. The belt guide #26 should be at the very bottom of #23 front idler and 1/16" from the top of the belt. Any parts you are missing should be available from a Simplicity dealer useing the 7000 series part numbers.

[chadkiser 0]

quote:

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Originally posted by UCD
Here is a better diagram and a picture from the Allis Chalmers 700 manual. If pulley #25 rear idler was smaller and in the correct hole it could not touch pulley #23 front idler. If pulley #25 was an oversize pulley it is possible it could rub pulley # 25. I suspect the problem is that pulley #25 rear idler is in the wrong hole on the bracket. It is in the hole the tension spring is supposed to go in. (blue line) AS you can see in the bottom picture there is plenty of clearance between the two pulleys if mounted correctly and for the correct alignment all of the parts have to be there and in the correct place as in the top diagram. The belt guide #26 should be at the very bottom of #23 front idler and 1/16" from the top of the belt. Any parts you are missing should be available from a Simplicity dealer useing the 7000 series part numbers.
[img]/club2/attach/UCD/7000-700PTOIdler.JPG[/img]

[img]/club2/attach/UCD/7000-700CenterPTO.jpg[/img]

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I guess I didn't describe it correctly. It's not the pulleys that are rubbing. The belt as it leaves the bottom of the rear idler (item 25 above) is rubbing against the bottom of the front idler (item 23 above) The second picture above shows alot more room between the belt and the bottom of the front idler/belt guard

[UCD 14]

Solution to problem is to buy a factory replacement for pulley #25 the correct spacers and belt guide and a new belt and you will be off to the races.

[Morris 0]

Chad, where in NC do you live? I'm in the Raleigh area...and yes I have had some similar problems on my Simplicity 700 deck but eventually sold that tractor before I got it all ironed out. I just replaced/rebuilt the PTO drive on my Allis B-1, though. Not easy but it came out well.

[chadkiser 0]

I'm in Mount Ulla, it's between Mooresville and Salisbury. About 30 miles north of Charlotte. I picked up a new belt yesterday, and I'm planning on working on the spacers on the 2 idlers, using stacked washers, to get them lined up better. I'm hoping that with the new belt the spacing between the belt and the front idler will work its self out.

[andrewk 0]

Without the correct diameter pulley, you are probably wasting time.