2135 PTO Belt Jumping Off

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grobinson

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Hello,

I have a Cub 2135 that I am struggling to solve a belt issue on, I have owned it for years and it has been a great tractor. Starting this year the PTO belt has started vibrating and jumping off the deck pulley frequently. I have replaced the belt, the tension springs, the bushings on the deck idler arm and still having issues. The pulleys all move well, no noise or wobble. With the deck in the highest position, the belt does not vibrate, the lower you go the more it vibrates. At 3/4 it will jump off the pulley. I have a shorter belt from another Cub I own and it helps a little but still a lot of vibration. The deck is pretty level but I am starting to think the front to back adjustment needs some work since the belt runs okay at the highest setting, can any provide the deck leveling procedure for the 2135?

Any other ideas?
 
reynoldston

reynoldston

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The deck is adjustable on that model. Front to back, the front mounding bar and side to side the adjuster is located right rear of deck. Are you using a OEM belt right??
 
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grobinson

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Thanks for the reply, I did start adjusting both the side to side and front to back and I could get the vibration to improve on one height setting but it became worse on other settings. The new belt is not OEM which I see can be a problem reading many other posts, I will order another one. The deck belt is very old but seems to work okay, since they are on the same idler pulley could this old belt cause the issue?

Thanks...
 
reynoldston

reynoldston

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grobinson said:
Thanks for the reply, I did start adjusting both the side to side and front to back and I could get the vibration to improve on one height setting but it became worse on other settings. The new belt is not OEM which I see can be a problem reading many other posts, I will order another one. The deck belt is very old but seems to work okay, since they are on the same idler pulley could this old belt cause the issue?

Thanks...
Click to expand...

The deck belt is a straight run as to the PTO belt makes a 90% twist to the front of the engine. This is the reason you need the OEM PTO belt. Yes both belts go to the double idler pulley in back of the deck. What shape are the bearings on this idler pulley. I just had to replace one of these pulleys nor too long ago because the bearing went bad and destroyed the pulley. A lot of things can cause a vibration, a bad bearing, bent blade , bad belt, engine skip, etc.
 
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bertsmobile1

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Vibratios = mechanical problem.
Bad bearing
Loose or broken mount or fitting
Flogged out pivot
Unbalanced blade
Worn out spring
Flogged out spring mount
Bent spindle
etc etc etc.

Because the deck lifts strait up & down rather than in an arc at the highest point & lowest point the deck pulley is furthurest out of alignment with the engine pulley and the belt is pulled the tightest.
As soon as it gets some slack the vibrations are strong enough to throw the belt so you have a mechanical problem
 
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grobinson

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Thanks for your replies...

I have been chasing this one for a while now, first new blades and belt (not OEM). Then both springs for the tension, then I noticed the idler pulley was moving up and down and found the bushings and pin were worn so I replaced them. The pulleys (front two below the engine and idler) along with the spindles move well with no noise so I guess my next step is an OEM belt. The original lasted for a long time so maybe this is my problem...

I will order a new belt and report back, thanks again for your help.
 
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bertsmobile1

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Cub do use a non standard size belt 25/32 " with a shallower side angle and while that might make difference, it is the vibrations that you need to find & fix.
The 2 bearings in the deck pivot are not standard sizes either.
It will be a case of watch & listen.
You might even need to get an assistant to sit in the mower.
I worked on a 2146 that was throwing belts and it ended up being cracks in the beck where the tensioning arm pivot bolts on to the deck.
The pivot was also at a funny angle to the deck where years of service has either bent it or the DPO had been using belts that were too short.
It should be square to the deck.
 
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grobinson

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Thanks for the additional comments, the new belt has been ordered. I will report back when I get the new belt on and review the other areas you suggested...

Thank you
 
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