JD 111 mower belt

[egbinor]

I have JD 111 11HP mower with a 36in mower deck with a single blade. Serial # M8803820 H8010. This thing wasn't running when it was given to me. After a valve job it's running great but keeps throwing the drive belt. When the deck is up the belt is running level with both sheaves but when lowered it looks too much out of alignment to me but I don't see a way to correct it @#!$%. I'm hesitant to buy another belt because the one on it looks pretty new and has a john deere number on it. Any help or suggestion would be appreciated, Thanks EGBinOR

 

[wore out]

Looking the parts catalog, it appears there were two versions of the single-blade mower, one with two drive belts and a "jacksheave", and one that uses a single long belt, I ASSUME you have the latter?

I've seen a lot of mowers where the belt alignment isn't pretty to look at, but they still work.

Is it possible there's a belt guide/restraint missing or not set or bent correctly so the belt can flop and jump off? I believe there are some guides at the engine end, for sure.

Do you know if it "jumps" first at the engine or deck end?

Looks like if you have the single, LONG drive belt the part number is M90958. Is that what you have?

It's also possible for a belt to look good and have an internal issue, broken cord, or whatever and not run as it's supposed to leading to it flopping off.

Just some ideas/rambling!

 

[egbinor]

Thanks for the suggestions. I have 2 belts, the problem is with the long belt to the engine. It is a John Deere M82460 CPT. It looks to be fairly new, however it has jumped the sheave a number of times. The last time it jumped off I really had it tight, a lot tighter than I usually would. Is there a way I can find the correct demensions of this belt before I buy a new one and how do I know this is the right one? By the way I like your handle. I'm a retired 81 year old heavy duty truck mechanic and pretty well wore out as well. Thanks again for any help. EGBinOR

 

[wore out]

(quoted from post at 22:15:57 05/13/20) Thanks for the suggestions. I have 2 belts, the problem is with the long belt to the engine. It is a John Deere M82460 CPT. It looks to be fairly new, however it has jumped the sheave a number of times. The last time it jumped off I really had it tight, a lot tighter than I usually would. Is there a way I can find the correct demensions of this belt before I buy a new one and how do I know this is the right one? By the way I like your handle. I'm a retired 81 year old heavy duty truck mechanic and pretty well wore out as well. Thanks again for any help. EGBinOR

It appears you have the correct part number belt.

Here's the details for it: