throwing belt

ohioelcamino · Aug 4, 2011

hello all i hope someone can help me. i have a 32 inch walk behind snapper and it runs and cuts great, but my left side drive belt wants to come off when ever it goes backwards regardless if your pulling back or the trans is moving it back. i have checked all the pullys and such for excessive play but it all appears normal. i hope someone can help im just not sure why its doing this. makes it real fun coming off the trailer.

thanks

fil shaffer

Short Game · Aug 4, 2011

I don't know that machine but check the alignment of the pulleys. Make sure they are exactly parallel and perfectly aligned. If one is canted to the other, or there is any stagger, belts will want to leave.

kco · Aug 4, 2011

My Kubota L275 was always throwing the fan belt for a time. It got worse and the belt would invert in the pulley as soon as I started the engine after reinstalling the belt.

The belt looked perfect but a mechanic told me the internal cords can break on one side causing the belt to flip over. I replaced the belt and it worked fine.

ametcalf · Aug 5, 2011

kco said:
My Kubota L275 was always throwing the fan belt for a time. It got worse and the belt would invert in the pulley as soon as I started the engine after reinstalling the belt.

The belt looked perfect but a mechanic told me the internal cords can break on one side causing the belt to flip over. I replaced the belt and it worked fine.

I agree with kco. I would try a new belt. I have a Honda rear tine tiller and a MTD riding lawn mower. When a belt starts giving me the type of trouble you are talking about I change the belt even though it looks good. Usually that solves the problem. Short Game is also right in that the pulleys should not be bent and should be lined up.

Dr_Zinj · Aug 8, 2011

You'd be surprised how quickly you can lose or shred a belt if the alignment is off by a quarter of a millimeter.

"Honey, what's this skinny washer for?"

Short Game · Aug 8, 2011

Dr_Zinj said:
"Honey, what's this skinny washer for?"

The one she found in your pocket when doing the wash?

JoeL4330 · Aug 9, 2011

If a new belt doesn't help, I would suspect the axis of rotation of that pulley is tilted ...can you determine whether the belt comes off above the pulley, or below it? That would suggest which way the axis is tilted (remembering that you are "reversing") ...and, assuming the pulley spindle shaft is not bent, you might be able to use a shim to correct.

You could observe, perhaps, by REMOVING THE BLADE(S) then elevating the mower (say, on jack stands, or lift w. FEL) and running it in reverse to try and duplicate.

Causes? a force that bent the shaft, and/or deformed the mower's top plate to which the pulley housing attaches (which shimming might be able to correct).

Another thing to try is to install a "keeper" or two, somehow...a "Z" shaped piece of stock (or, two angles fastened together in opposition) ...initially (at least) bolted to allow some adjustment ...making sure all edges are rounded