Mowing mower keeps throwing the belt

[Little Red Tractor]

I recently got a Cub Cadet 6824, and before mowing I replaced the spindle belt as the one on it was a bit chewed up. About 1000 feet into my first mowing of the year, it threw the belt. I reset it, and it did it again, again and again...and once more for good measure. All that in about an acre and a quarter.
The only thing that seemed to keep it on, finally, was running the engine just under the "green" range--about 2800 rpms or so.

The spindles appear tight and have been freshly serviced, The gearbox is tight to the mounting. I noticed that the pivot point point of the idler arm seems to be a bit wobbly, but that's about all I can find.

Any thoughts?

 

[Bird]

It's been a long time ago that I had a Cub Cadet doing that (late '90s). And it was simply pulley alignment. Once I figured out which pulley and got them all aligned properly, no more problem. I'm guessing you found your problem with that idler arm.

 

[TRR]

I'm not familiar with your setup, but I'm guessing that your drive pulley is on a horizontal shaft and your mower pulleys are on a vertical spindle. Thus the belt needs to make a 90 deg turn. Check the type of belt you are using. The automotive belts I believe are an "A" type belt and do not make that 90 deg turn without rolling over. You will probably need something like a "B" belt or wider. (If the other suggestions don't fix it.)

Conventional V-Belts - Belts Sizes A - B - C - D - E Section Belts

 

[Little Red Tractor]

I'm not familiar with your setup, but I'm guessing that your drive pulley is on a horizontal shaft and your mower pulleys are on a vertical spindle. Thus the belt needs to make a 90 deg turn. Check the type of belt you are using. The automotive belts I believe are an "A" type belt and do not make that 90 deg turn without rolling over. You will probably need something like a "B" belt or wider. (If the other suggestions don't fix it.)

Conventional V-Belts - Belts Sizes A - B - C - D - E Section Belts

Thanks TRR, but it's not the setup you're thinking of. It's a PTO driven deck, and I'm using the OEM part, so it's not an improper belt issue in any way.

 

[MarkV]

Had a similar experience with a Cub Zero Turn mower and it was a bad bearing in the idler pulley. Not sure of your set up but might check there.

MarkV

 

[yelbike]

Check for horizontal pulley alignment as well. Meaning the pulleys should be all be at the same elevation from the deck. Also check that they are all plumb, so each spindle is "square" to the deck plane. Thirdly, check each pulley running surface for wear, pulleys do wear out. How many hours??

Did you run it with the old belt? Although you stated its an OEM belt, counter parts people do make mistakes sometimes.

 

[scoops]

This was a known issue with the belts coming off, the fix was to add a pulley
I will take a picture of mine tomorrow to show you where the extra was placed.

My belt never comes off anymore.

 

[Little Red Tractor]

Check for horizontal pulley alignment as well. Meaning the pulleys should be all be at the same elevation from the deck. Also check that they are all plumb, so each spindle is "square" to the deck plane. Thirdly, check each pulley running surface for wear, pulleys do wear out. How many hours??

Did you run it with the old belt? Although you stated its an OEM belt, counter parts people do make mistakes sometimes.

I never ran with the old belt. It had a couple cuts, so I replaced it when I had the deck off the tractor to sharpen the blades.

 

[Little Red Tractor]

This was a known issue with the belts coming off, the fix was to add a pulley
I will take a picture of mine tomorrow to show you where the extra was placed.

My belt never comes off anymore.

Looking forward to the picture!

 

[ultrarunner]

Only a suggestion.

I had trouble with a mower that was throwing the belt... that is why I got it for next to nothing.

Putting a Gator Back Premium belt solved the problem...

Guess not all belts are created equal... the notched design allows for greater variance.

May or may not be applicable.

 

[yelbike]

Only a suggestion.

I had trouble with a mower that was throwing the belt... that is why I got it for next to nothing.

Putting a Gator Back Premium belt solved the problem...

Guess not all belts are created equal... the notched design allows for greater variance.

May or may not be applicable.

I heard those gators are really worth it.

 

[OhioGuy]

Here's a link to an old thread where I posted a picture af a pulley that was added in later production. It appears its sole purpose was to limit travel/belt jumping off?

This was a 60" deck on a 5252, it may be the same deck?



http://www.tractorbynet.com/forums/cub-cadet/61374-cub-5000-mmm-eating-belts-3.html?highlight=5252


Good luck,
Curt

 

[Little Red Tractor]

Very similar looking. My deck has a shoulder bolt there which CC customer Doppler said was an add on to keep the belt running true. It was not...on my model...equipped with a pulley.
Customer support is pretty sure the problem is the pivot on the idler. I ordered a few new parts to fix it. I'll let you know how it works out.

 

[scoops]

That's all mine has is a shoulder bolt, not the whole pulley like on the picture,
But that was the fix

I apologize but I can't get the picture today as we had a rare nor Easter that is dropping snow and rain like crazy and my deck
Is outside. When the rain stops I'll remove the covers so you can get a good view of the entire pulleys and belts

 

[scoops]

Here they are.
I do have an extra heavy duty spring that I installed on there.

 

[Little Red Tractor]

I think I'm going to add a heavier spring, too. I was quite surprised at the light pull on this.

 

[scoops]

If you need one of those springs let me know, it would just cost you just shipping.

 

[Little Red Tractor]

Thanks for all the help and input on my problem. I ordered a new idler arm and bolt, and another member here sent me a heavier idler spring. The combination has solved the belt throwing problem.
While I had the mower off, I noticed that the universal joint, where it attaches to the mower's gearbox, was very loose. The U-joint is held to the box's input shaft by a snap ring and is bolted through. The hole on one side of the U-joint was much larger, I suspect for a special bolt which would apply pressure to the shaft. I had some spacers that fit and when I tightened it up it took the rattle out of the joint--and it runs true--or appears to. It seems to have taken some vibration out of the mower.

 

[scoops]

One thing I notice bout the vibration is that , at least on mine, the shafts are only balanced one way,
Mine used to vibrate, and I tried it all 4 ways to I found the one that took out the vibration.
Once I did that , I marked the two sides so it would always go back on the same way

I am speaking about both sides of the half shafts of I confused anyone

 

[Little Red Tractor]

One thing I notice bout the vibration is that , at least on mine, the shafts are only balanced one way,
Mine used to vibrate, and I tried it all 4 ways to I found the one that took out the vibration.
Once I did that , I marked the two sides so it would always go back on the same way

I am speaking about both sides of the half shafts of I confused anyone

Actually, I knew just what you meant.