John Deere Z355E pulley

[CDStanton87]

Had a recent issue with one of the blade pulleys on my Z355E. I’ve had it for two years and no issues. First two times cutting this year, one of the pulleys stripped out. The nut securing the pulley to the post has come undone and the center of the pulley as gone from hexagon shaped to circular or oval shaped. Anyone know what causes this? Nothing is obstructing the blades.

 

[mechanic mark]

try using a self locking nut, use JD OEM parts, belts, pulleys, etc.

 

[bertsmobile1]

Vibrations cause it.
Lack of a proper maintenance regime and most likely a poor pre delivery is the reason why it happened.
When done up properly they do not come loose usually.
Occasionally I will find a loose nut during a routine service but rarely one that I have tightened comes loose again , although I only have 5 years under my belt.
Most loose nuts get found on a first service so I put that down to inadequate dealer pre-delivery.