Repairs Yard-Man Lawn Mower Drive Wheels Lock-up

jemret

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May 8, 2012
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My 16 year old 21" Self-Propelled Model #12A-979L401 rear drive wheels lock-up when pulled backwards. How can I tell if the transmission releases? I took the belt cover off and replaced the belt, although I didn't see anything wrong with the belt. I know the transmission is sealed but is there away to check the lubrication in it? After 16 years it may need some lube. All suggestions appreciated.
 

deminin

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May 19, 2014
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My 16 year old 21" Self-Propelled Model #12A-979L401 rear drive wheels lock-up when pulled backwards. How can I tell if the transmission releases? I took the belt cover off and replaced the belt, although I didn't see anything wrong with the belt. I know the transmission is sealed but is there away to check the lubrication in it? After 16 years it may need some lube. All suggestions appreciated.


I had the same thing happen to my Toro walk behind. Seems like a few years of washing dirt and debris off it caused a buildup in the rear wheel drive gears. I removed the wheels...1 Bolt, each....and cleaned out all the muck and lubed the drive gears with some grease, and it has been fine since.
 

jemret

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I checked for dirt and debris but there was no buildup in the rear drive wheel gears. One further thing I did notice was a squealing noise that seemed to come from the transmission gear box every time I pulled the mower backwards, even when the engine was nor running. I noticed there was a bearing in the belt keeper that sits under the belt pulley. I am wondering if this bearing could be dried out causing the squealing noise and subsequently locking up and causing the mower to be hard to pull backwards. Any thoughts on this problem is appreciated.
 

deminin

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May 19, 2014
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I checked for dirt and debris but there was no buildup in the rear drive wheel gears. One further thing I did notice was a squealing noise that seemed to come from the transmission gear box every time I pulled the mower backwards, even when the engine was nor running. I noticed there was a bearing in the belt keeper that sits under the belt pulley. I am wondering if this bearing could be dried out causing the squealing noise and subsequently locking up and causing the mower to be hard to pull backwards. Any thoughts on this problem is appreciated.

If you can locate the source of the "squealing", you will probably have the problem isolated. If its the belt keeper, remove the belt, and turn the keeper, and it should spin freely...if not, the bearing is probably shot. If that seems ok, you should be able to raise the rear of the mower, and set it on something solid....then turn the wheels backwards and see if you feel any resistance, or hear any strange sounds.
 
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