Help! Deck belt twisted.. use just one belt? (pics)

[656_tractor 14]

Hi All,

I need to mow my lawn but one of the dual mower deck belts decided to twist itself, pop off  and PUSH the second belt off - and halt the blades!  I am not sure why this happened (would like to know...) but one of the dual belts became stretched or something and the other is fairly tight.. I didnt buy them too long ago.    Pics below for any advice.  Also, can I just cut off the loose one.. and run ONE belt?   I dont want to mess with adding another belt and screwing up my mower deck again. . The last time I did that, I screwed up the blade timing and they were slamming into each other that cause all kinds of a mess with this deck where it almost destroyed itself..   1966 WH 656

 

 

[Ed Kennell 38,052]

Was the pulley rubbing on the attach-a-matic bracket when the deck was latched into the bracket ?

[daveoman1966 3,745]

You've gotta use the OEM belts on these old deck.  They are a MATCHED pair and of proprietary geometry such that after-market belts just plain don't fit right.  ps...one a belt is twisted, FUBAR.  The matched set of belts for your deck is #1578 (need 2).  

[656_tractor 14]

Thanks for the replies guys! 

"Was the pulley rubbing on the attach-a-matic bracket when the deck was latched into the bracket ?"

No.  I dont believe so.  That mark in the paint is rub marks from the belt getting pushed into the bracket.

[squonk 41,041]

I run Napa 3L370W belts on my gear drive decks with no issues for years. It's not the belts fault as long as you had them tight enough and they were the correct length. Do you have the number of the belt you used?  Belts do not stretch either. The sides wear down giving the illusion of a longer belt because they sit down deeper into the pulley when they wear.

 

You either hit something, a stick got in there and flipped the belt.  Or the cross bearings are starting to fail. I have seen those bearings fail where they stop spinning and the power from the engine will keep turning the shaft and wear down the shaft where the bearing rides. The bearing is supposed to be a press fit on the shaft and into the bearing stands. When this all happens the shaft is shot ,the stands are shot and the shaft can move side to side causing an alignment issue and start wearing down a belt and throw it off

Edited April 10, 2023 by squonk

[squonk 41,041]

Matched belts were a thing back in the 70's on back but not anymore. Manufacturing methods have improved so much Gates guarantees it's belts to thousandth's of an inch. If you called Gates and said I want a matched pair of XXXX they would grab 2 belts, zip tie them together and send them to you as a matched set.

 

I sold Gates for 10 years and for the past 20 have dealt with all sorts of belt drives in industrial applications. There are "Matched TORO 1578" belts out there. If you google them a lot are just replacement belts that are the right length and width. There are some "TORO" branded matched belts. But I would be leery of them as they could be quite old. Inspect them carefully

[ri702bill 8,296]

19 minutes ago, squonk said:

Quote

But I would be leery of them as they could be quite old. Inspect them carefully

 

Sounds like advise before going to a Geriatric Harvest Dance !!! 

[656_tractor 14]

" Or the cross bearings are starting to fail. "

 

What is a 'cross bearing?"  Thanks.  I just had all the bearings replaced/pressed on on the blades to deck/gears; and a new gear.  

 

side note:  my deck is not PERFECTLY straigh.. a slight bit off.  I placed foam shims to adjust it slightly.. eh maybe like 2-3mm  (you can see one in the top of the pic weged)  I wonder if that slight adjustment did it.. :/   

 

p.s. On the stretching.. the belt is currently stretched somehow. The outer one deflects a lot more than the other. :/

p.s.s.  Does anyone know where I can find another deck for this tractor as a backup in case?  I plan to keep this tractor forever.

 

Oh!  Edit - could real heavy grass do this where the drive belt from the engine is real tight and new (it is) but the deck belts arent as tight and the desk slows down but the engine keeps spinning?  Sorry, just trying to think of anything.

Edited April 10, 2023 by 656_tractor

[squonk 41,041]

The pulley on the deck where the gears are is attached to a shaft that goes across the deck. Under the gear covers you will see a gear that mates to the spindle (blade gears) #28. The plate just inward from that gear is the cross shaft bearing stanchion #25. The cross shaft bearing is # 26 There is another on the other side (not shown). The bearings are pressed into the stanchion and pressed onto the cross shaft # 22. When the bearings start to go they will start to seize. They will either spin in the stanchion, Spin on the shaft or both. When this happens the pulley and shaft will chuck side to side causing the cross gears and spindle gears to bang into each other. Causing a rattling/banging noise. belt misalignment and at worst the blades jumping time. There is no way to grease these bearings. If they are original there is a good chance they are on the way out.

 

 

 

You didn't mention what brand belt you used. Belts are really strong and don't "Stretch " in normal use. It would take a violent sudden stop with the power on to stretch it. I would think the if one belt was looser from the beginning it was either due to a cheap poor tolerance manufacturer or the drive and driven pulleys not aligned. If they are crooked, one side of a pulley will be closer to the drive pulley than the other. 

Shimming the deck could throw the alignment off and yes hitting tall grass to fast cpuld toss a belt.

 

I wish you luck finding a good deck. I went thru about 6 decks that I was told were "quiet and smooth" until I found a decent one.

 

 

[656_tractor 14]

 

Ok thanks very much Mike.  Yes this bearing was just replaced.  I had the rattling banging previously which caused me to replace all those bearings (and #26 there) . :/   I think this belt is napa 3771 IIRC...   The thing was mowing fine for 15 minutes, and then belt smoke which I learned to QUICKLY shut it off now...  I havent had a lot of luck with this deck.. hmm looks like theres  a #42 bearing too.. NEVER replaced I am sure.. I think If I should be able to turn the blades freely.. - maybe I can use the one belt just to get my grass done and try again.  I think yo uare saying I should look for some kind of side to side play - that will tell me if something is wrong.. edit. Checked, no side play.  
 

maybe something did get stuck… I put the guard in again just in case.   :/ mo idea otherwise why this thing siezed or belts jumped  Everything spins fine now.  AAND … the last fella that put this together last season had the tensioner at its lowest setting!!!!   I think we found it.,. Its the last thing u think about….

 

Edited April 11, 2023 by 656_tractor

[Ed Kennell 38,052]

On many of these decks I have found the ball socket in the cross bar was worn out and was not keeping the item 37 rod fixed to the cross bar.  This allowed the left side of the deck move to the rear misaligning the drive pulleys.    I usually cut the ball of item 37, drilled and tapped the rod for a 3/8" bolt. Then drilled a hole thru the support crossbar so I could bolt item 37 solidly  to the cross bar.      I don't know if this problem exist on your deck, but if it does, it could cause the misalignment of pulleys resulting in belt damage.

[moe1965 737]

I'm not sure but I have never ran  across a sectioned belt ( cogged ) used other than on a alternator on a car.   I think it should be a solid belt or fractional belt that can take a load.  

Edited April 11, 2023 by moe1965
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