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Deck belt keeps breaking

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#1 casualhero OFFLINE  

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Posted August 10, 2016 - 01:08 PM

O.K. I'm starting to get a little irritated. The belt on my 50" gravely deck has broken for the second time (after about 8 hrs use each time). I tightened the idler to factory spec. each time with the same results. Any input/diagnosis would be appreciated.

#2 crittersf1 ONLINE  


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Posted August 10, 2016 - 03:30 PM

Cheap belts? Bearing getting hot? Pulley misalignment?

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#3 chieffan ONLINE  

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Posted August 10, 2016 - 03:56 PM

Or all of the above.  FHP belts do not last long as they are not built to fit the pulley.

#4 casualhero OFFLINE  

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Posted August 10, 2016 - 04:03 PM

I believe I'm using a Sten OEM belt. How do I check for proper alignment? I'm pretty much a noob with Gravely's and learning as I go so forgive me for stupid questions.

#5 glgrumpy ONLINE  


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Posted August 10, 2016 - 05:23 PM

This for the rider in avatar?  I would pull out the deck, remove covers to see good. Turn each spindle and see if nice and smooth and loose, or kinda binding. Also wiggle them to see if any big  play in them. The idler arms on many decks rusts at it's pivot. If not easy moving, take it off, clean up the pivot bushing till nice and free moving, bolt back down. Make sure any washers or spacers go back in orig space or it will just tighten when bolting down, not what is should do. Make sure that same tension arm is not bent out of alignment. Look for where the belt rides on that pulley if a flat one. Make sure that pulley also spins smooth and easy. Most times bad pulleys just get replaced, have sealed bearings made into them.


NOW, just realizing you may be talking the drive belt?  About same things, make sure all the pulleys move freely and with no big play. grease them if required?  This deck must have a Mule Drive with double pulley system to drive?  I don't know what Gravely's actually have. All the tension arms must move and float, one usually has a spring for tension, other has the eye-bolt for tensioning?? Make sure all pulley's straight and no knicks or bends at outer edges that cut into belts. Is there little metal bars or rods to help guide the belt, keep it on pulleys when it is loose?  Missing ones may allow belt to move off the pulley some, then when you engage it sort of starts, but rolls over a sharp edge or something before seating?  The guides prevent that.  You have a manual for the deck?  Best look into one if not, a parts and owner's users" if seperate. Check the diagrams with what you are doing or owning.

#6 casualhero OFFLINE  

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Posted August 11, 2016 - 05:05 PM

I pulled the mower deck off and checked all the pulleys, they are all spinning freely and no wobble to them whatsoever. They had a bit of rust on the working surfaces so I wire wheeled what I could and sanded down the rest to clean them up.
I gave the spindles some grease at the fittings and put the whole unit back together again. Going to do a test mow and then pull the belt covers off and check for excessive belt dust to further diagnose.