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formariz

What is destroying my belts?

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Are you sure the center slot  in the  tensioner bar is not  hitting the bolt when the belt is under load and releasing the tension\?     May try a shorter belt.

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This is getting to that point where I'd offer to buy it from you but I couldn't afford the belts.

 

Here's another suggestion: Belt speed too high (or weak tensioner spring) causing it to stretch at speed and lose contact momentarily.

 

Reference this picture of my running drill press:

 

2D6315D3-308D-49AC-A465-F50B17119A9A.jpg

 

Edited by clip

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2 minutes ago, Ed Kennell said:

May try a shorter belt.

Which would put more tension on the spring...might be something to try if you just happen to have a shorter one around?? Maybe we could loan you one to try what size is it?

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I looked thru the manual to see if there was any instructions on how tight the bolts should be on the tension bar . There were none. You may want to try the following. Put pressure on the idler pulley so the belt is tight. Tighten both bolts on the tension bar so you can barely move the idler pulley. This is the way I use on my tension bar set up. 

My belt has been running on my deck for 3 or 4 years maybe longer with the above set up. I have never had any problems with cutting grass no matter the thickness or height. I have had to reduce the ground speed on the tractor in very tall wet grass.

Are you running the engine at full speed?

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22 minutes ago, elcamino/wheelhorse said:

I looked thru the manual to see if there was any instructions on how tight the bolts should be on the tension bar . There were none. You may want to try the following. Put pressure on the idler pulley so the belt is tight. Tighten both bolts on the tension bar so you can barely move the idler pulley. This is the way I use on my tension bar set up. 

My belt has been running on my deck for 3 or 4 years maybe longer with the above set up. I have never had any problems with cutting grass no matter the thickness or height. I have had to reduce the ground speed on the tractor in very tall wet grass.

Are you running the engine at full speed?

I run the engine at full speed and use very slow ground speed.

So if I understand your suggestion, you basically stretch the belt manually and tighten the adjustment so it is fixed. There will be no fluctuation in the spring tension as it is used.

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There is no fluctuation in the tension. I learned that from my father who used a 37 inch SD deck on a Commando 800 from 1972 until his death in 1991. He changed deck belts very seldom. I don't know if my system is right or wrong but it works for me.  I think you have tried every thing we can think of except buying a new deck. 

The deck I am using came with the 1987 310-8 that I purchased years ago. It looks to be the original deck. After using it for about 5 years the idler pulley died and destroyed the deck belt. I replaced both the pulley and belt with Toro parts and have not had any problems.

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2 minutes ago, elcamino/wheelhorse said:

There is no fluctuation in the tension. I learned that from my father who used a 37 inch SD deck on a Commando 800 from 1972 until his death in 1991. He changed deck belts very seldom. I don't know if my system is right or wrong but it works for me.  I think you have tried every thing we can think of except buying a new deck. 

The deck I am using came with the 1987 310-8 that I purchased years ago. It looks to be the original deck. After using it for about 5 years the idler pulley died and destroyed the deck belt. I replaced both the pulley and belt with Toro parts and have not had any problems.

Between your suggestion and Clip's post it is beginning to make sense of what may be happening. Belt may be actually "attempting to come out of pulleys and getting sliced in the process.

So understanding the problem a little better is then tension bar designed to "float" or is it supposed to be hard bolted as you suggested? I did not see anything in any instructions to that effect.

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It's supposed to float.

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The way the tension bar is mounted on the decks does not make sense to me.The way WH designed and placed the tension bar and spring appears to be backwards. To my way of thinking the job of the spring is to apply constant pressure on the idler pulley to keep the belt tight. Every manual I have seen indicates the placement of the tension bar and spring in the position that you have them. Like I said my father always tighten the tension bar down as much as possible and I am just following his example. Hope this helps.

Squonk ,I know it should float but that way that the bar and spring are positioned it keeps the deck belt loose. I have checked a few manuals for 36 and 37 inch decks that work on c series and 300 & 400 series and they all show the same diagram.  Where is an engineer when you need them? Redneck engineering is not working in this case. 

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IMG_5249.JPG

Jim, you must be missing the location of the attachment point of the ends of the spring.   In this photo, the bottom end of the spring is attached to the sliding bar and the top end is fixed to the deck. Therefore the spring is pulling the sliding bar and pulley up and tightening the belt.  

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23 minutes ago, Ed Kennell said:

IMG_5249.JPG

Jim, you must be missing the location of the attachment point of the ends of the spring.   In this photo, the bottom end of the spring is attached to the sliding bar and the top end is fixed to the deck. Therefore the spring is pulling the sliding bar and pulley up and tightening the belt.  

The spring on my deck is attached to deck shell and it does put tension on belt,I already tightened it as Jim does so I am going to give it a shot that way. Its so far the only explanation that makes any  sense of what is happening to me . It seems to me that the if tension bar is designed to float ( which it obviously looks like that ) that the spring specified has insufficient tension to keep that belt under proper tension all the time. I am actually going to use a new belt and test this out. Counting on them being destroyed I have here a good supply of them.

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If your spring is not keeping tension on the belt. 

   Three things  could cause this.

1. the spring is too weak

2 ,the belt is too long

3. the sliding  bar is  not sliding due to the end of one of the slots hitting a bolt.

 

In the above picture, you can see the spring is stretched  approx. 2X its relaxed length which puts quite a bit of tension on the belt.

 

It should be noted this spring loaded constant belt tensioning system will automatically make adjustments for varying belt length due to elongation from heat and wear and pulley runout.      The tension system is also the slip clutch if a blade strikes an object.

Edited by Ed Kennell
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This might not help correct Formariz's  belt eating problem  but I have seen belts chewed up  for the reasons I am going to explain.

 

One of the things I have noticed on these 36 inch mower decks that causes trouble is the oval hole in the idler arm  sometimes gets distorted and slides sideways in addition to back and forth.     I change the carriage bolts  about every three or four years when redoing a deck and check the holes on the idler arm.    These decks pictured in this thread have two different idler arms -one with the black plastic  slider and one with the U shaped  nylon type idler block that goes around the top of the idler arm and rests on a 1/16 inch slider with square holes for the carriage bolts to come thru from the bottom.   These U shaped nylon  (and it may be some other material) slide blocks  can wear side to side too.     The U shaped blocks are no longer made and  although I have several that still are in great shape after 40 plus years of use they will wear and we will need replacements.   The black round type  are  still made and Glen Pettit also sells some of these variety.   The idler arms must slide easily and without bouncing around.

Edited by Lane Ranger
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Ed and Lane , I think you are correct , I took some photos of my deck this morning ( very bad quality photos ) and my spring is about 2 times its normal length . Same as Ed's photo.Either the spring is incorrect or the belt length is wrong based on the photos that Formariz supplied. I am going to check my tension bar in the AM to see if I have the bolts too tight. I am also going to see if I can provide part for the spring. I don't remember seeing any dimensions for the belt. 

It appeared to me that Formariz's  idler pulley was incorrect in height. There is very little interior of the pulley showing on my deck where as Formariz photo of the belt and pulley indicate a lot of pulley showing. If the belt is too loose it will move up and down on the idler pulley . My pulley has  the following outside dimensions. 3 1/8 inch diameter by 7/8 inch thickness. In Formariz's original photo's the spring is not stretched like the spring in Ed's photo.

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Belt is #8411 which is 1/2"x77". Idler I have is #7434 which is 3-1/8"x 7/8". Since bar slides properly as you can see in video and all other components are correct as per specs including spring which I have #100071 , the only option here seems to be that spring is inadequate. I am going to try it with fixed bar (non floating) and new belt. If nothing happens to belt, then I think it will be safe to assume that it is the spring. New spring is identical to old one and stretches about the same. Shown are photos of old spring next to new one extended. Is is extended that much now because I forced it as much as possible and I 'locked"  the adjustment, otherwise it only extends half of what is now. Also at this point the adjustment slot in bar by spring is bottomed out while one on opposite end is in center. I could not stretch that spring anymore anyway. Just to eliminate another variable I checked belts I have and they are 77".

 

 

IMG_0215.JPGIMG_0217.JPGIMG_0216.JPG

Edited by formariz

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I sure hope it works . I have been thinking about your problem most of the day and I don't know what else to suggest. Keep us up to date on your progress.

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I was looking at it wrong and after getting home and going out and looking at my decks I see it. One of my late model decks goes the other way. All my older decks have the nylon blocks like Lane says and the tension spring is much more sprung than what Formariz is but yet his is the right length spring. Any chance you might have gotten a mistake packaged spring or one that wasn't made right? After seeing the way it jumped back and forth in those blocks or slots like Form's is I used to schmag some lube on in but all that did was collect dirt. I think one of Ed's 3 possibilities is right. When I put my belt on I think man that spring is holding that tensioner way too tight but yet no problems?? Just gotta be not enough tension on the belt, belt slips,belt runs hot destroying itself. One would think though you could hear the deck not winding out tho or slowing down?? Yes indeed perplexing Cas ....keep us posted.

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11 hours ago, formariz said:

Belt is #8411 which is 1/2"x77". Idler I have is #7434 which is 3-1/8"x 7/8". Since bar slides properly as you can see in video and all other components are correct as per specs including spring which I have #100071 , the only option here seems to be that spring is inadequate. I am going to try it with fixed bar (non floating) and new belt. If nothing happens to belt, then I think it will be safe to assume that it is the spring. New spring is identical to old one and stretches about the same. Shown are photos of old spring next to new one extended. Is is extended that much now because I forced it as much as possible and I 'locked"  the adjustment, otherwise it only extends half of what is now. Also at this point the adjustment slot in bar by spring is bottomed out while one on opposite end is in center. I could not stretch that spring anymore anyway. Just to eliminate another variable I checked belts I have and they are 77".

 

 

IMG_0215.JPGIMG_0217.JPGIMG_0216.JPG

These three pictures clear up the problem. 

  The first picture shows the spring is stretched about the correct amount.

The second picture shows the guide bolt to be where it should be...centered in the slot to allow the bar to slide.

The third picture clearly shows the guide bolt is bottomed out in the slot preventing the  the bar and pulley from moving to the right  and therefore it is not  putting any tension on the belt.

I see two two possible fixes...  move the bolt in the third picture to the right one inch  or use a one inch shorter belt.

 

With the bar bottomed out against the guide bolt, a stronger spring will do nothing to increase the tension on the belt. 

Edited by Ed Kennell
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I've been working on my 36" deck, which has the same tensioner as yours and I thought I would rob the tension spring from another deck, but it has the different style tension slider.  So after checking the part numbers I found they are different springs, and I ordered the correct one to avoid problems.  I began working on the deck again last night after work and found the idler pulley bearing is shot, so I gotta get a new one before reassembling. :(

 

#8411 is the correct belt, so I'm convinced that is not your problem.  Your idler pulley does appear wider in your pics than mine, but hard to say for sure.

 

As I said in a previous post, I don't have much experience with decks, but thought you could use a little affirmation.

 

I was thinking about your problem as I drove home from work yesterday and I remembered someone here mentioned to test each spindle by using an electric drill to spin them individually.   Why not spin the whole thing with the belt on with a drill or impact wrench while it's off the tractor?  Of course safety is a concern, unless you remove the blades.   This way you may able to see what is exactly happening to the belt as everything turns at speed.  

:twocents-02cents:

ca78d77f85e67fa8709f038bdd1e51e7 (1).jpg

Edited by TDF5G
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Good eye Ed I think you might have nailed it. Why is there slot left on the other side tho?  Shorter belt should do it too as it would move the tension bar more to the left but might bottom out the slot on the other side?. Could the manual be wrong on the belt size? One of my decks called out for a 85 1/2 belt and blades seem to slow down in tall grass or lower cuts & Tractor Supply of course doesn't have theses odd size belts that Toro used so just went with a 85 and all was well.  Maybe try a 76" Cas.

IMG_0216_JPG_afe299d8649237202a6f707c3f92cb95.jpg

Edited by WHX61/3
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I agree Jim, with a shorter belt, you would risk the other slot bottoming out on the opposite end.    This would still allow the spring to apply tension, but it may be difficult to get the belt on.

It appears that. either the bolt or the slot is in the wrong location.    Is it possible there are more than one design of these slotted bars and we have the incorrect one on this deck?

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I looked at the diagram of the deck . I got this diagram off the Toro parts site in 2012 when I needed belt and idler pulley. It shows to holes in the tension bar which could be used for the idler pulley . The holes are about an inch apart, I wonder if the idler could be in the wrong hole. The holes are so close to each other that the idler would cover up the incorrect hole. The diagram is for a 36 inch RD ,but it is the same for the 37 inch SD .

Ed , I checked my deck today and my bar does move , the tension is very tight ,I am going to get so new sliders . I hope this diagram is attached.

Scan0014.pdf

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Jim :  Your scan of the idler piece is a good reference.   Both of those holes  that you point out for the idler pulley are threaded,    Not sure why there are two holes but  putting that pulley in one or the other is going to change the tension on the idler arm -with whatever belt is on it!

 

 

I bought a  312 tractor with a recycler deck two years ago and the deck needed several parts replaced.   One of the parts that was worn badly was the idler arm.    As you can see the idler arm holes for the slides are egg shaped and the  idler arm has  cuts in it where the idler pulley skipped and cut into the  arm surface.   The telltale sign of the problem however is  the ring around the  hole where the idler pulley was placed and it is apparently the wrong hole for installing the idler pulley based on the scanned drawing Ed posted above.  

 

I replaced the idler arm with a new one from Toro which was about $40 but it was needed to make this mower function correctly.  Also I had to change the center lift piece in the mower rack as it was damaged with an egg-shaped /oblong hole worn it it also!

 

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Edited by Lane Ranger
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