Belt jumping on RDTH72 Finish Mower

[felixedo]

I have an RDTH72 rear finish mower that I replaced the gearbox on last summer. The belt is jumping off one of the blade spindles. I have no idea how long I run it in that condition, because I don't realize it's off until I smell the rubber burning. I have no frozen pulleys. They all turn with varying amounts of resistance. What is the best way to determine why the belt is coming off. Also, I would like to figure this out with the current belt, before I trash a new one. Hopefully that's possible. TIA.

 

[RjCorazza]

I am not familiar with your particular mower, but some things to look at...
Idler pulley tension, and the actual pulley condition. I had a walk behind that was throwing the belt, and eventually found the idler pulley had 2 halves that were coming apart. Couldn't tell until removing the belt and getting hands on it.
The other thing that comes to mind is debris jammed in the spindle pulley, like a small stick or acorn. That gets the belt jumping until it comes off.
Good luck.

 

[old and tired]

I have an RDTH72 rear finish mower that I replaced the gearbox on last summer....

Did you buy the replacement gearbox from Bush Hog? OEM or aftermarket? I would check on the gearbox alignment.... if it's sitting on the deck flat. Let us know what you find out.

 

[felixedo]

I did not buy the gearbox OEM. I got it from Messicks. It sits on the deck flat. I should say, Messicks is a Bush Hog dealer and they sent me the gearbox I ordered. It is obviously a Chinese product, but that may be OEM at this point.

 

[slckeys]

On my rear finish mower, my idler pulley is out of alignment. I shimmed it up and no more issues. So I would put the belt on, and spin it by hand to make sure your belt/all pulleys are spinning level. Maybe something is pushing or pulling the belt out of alignment...

 

[Williy]

If you have a bearing/pulley that can wobble
can be the cause also if the pulley is tilted some
what can also cause belt to jump off. You want
the belt to fit in the grove

Check out what this guy is saying:

willy