A practice I have gone to is using bolts (with lock nuts) in place of the lynch pins, especially with a rotary brush cutter. My experience and from stories (horror stories) that I've heard, is that brush (or your problem/experience) will cause the loss of the pins, and then the damage can occur as a result. The worst was losing the pin in the lift arm at the tractor end, causing the twisting and breaking of the opposite casting (BIG $$$$). Seems that brush has a way of quickly finding the lynch pins, removing them, and causing the loss of the pin it is holding. Removing the lock nut and bolt is a little time consuming, but better than a breakdown in the thick brush on the back forty (when the pin came out of the connector between the rock shaft arm and the lift arm meaning the rig couldn't be moved until the parts were replaced). And just finding the lost parts on a weekend when the dealer is closed, causing a visit to the rental place to get a metal detector for a half day (found it in 5 minutes), is more time consuming.
