Belt Auction

Lawn mower transmission belt broken?

What causes a lawn mower transmission belt to break? I believe it is a John Deere.

Public Comments

1. They do wear out. If it frequently breaks, something may be wrong in the pulley system, but if you only have to replace it once a year, that's fairly normal.
2. Age and too heavy a load causes the belt to break. Were you mowing heavy clumps of grass? Heavy clumps of grass break a lot of mowing belts. To cut them, take small slices off of the clump with one side of the mower. If your belt was more than five years old, then it should be replaced anyways. When you replace the belt, buy a Kevlar reinforced belt. It is more expensive, but has about twice the strength of a normal belt.
3. Belts wear on the sides, that is where they grip the pulleys. As they wear they ride deeper into the pulley giving the impression of being longer. This adds to the possibility of the belt slipping under a load. Slipping causes the belt to heat up, heat is the killer of belts. So, it is a combination of things that cause a belt to fail. If it is breaking more that once a season or two there may be an allignment issue with the tensioning pulley or it could be routed incorrectly. Installing a belt that is a bit too long will also shorten the service life.