PTO Shaft to Gearbox Bolts Keep Breaking!

[airbiscuit]

I'm wondering if it's a combination of variables:

1. The hole in the collar or shaft is slightly oversized or wallowed
2. The bolt isn't long enough (collar rests on threads)
3. The bold isn't tight enough - allowing it to spin and degrade
4. There is some unusual vibration at the gearbox
5. There are demons at play

First I would use a longer bolt (so no threads in the collar), use a lock washer and tighten it tight. Maybe wrap the nut end with duct tape so you can retrieve it if it fails.

If that fails, see if a 14mm bolt will fit in there snugly.

 

[SPYDERLK]

Using a 6** type Loctite and a grade 8 bolt would stop this problem. Heat would be needed to get it apart later.

Unless you unfortunately happen to use #620, which is strong up to 232C. This formulation is one of the strongest to start with, and gets stronger as it ages at mild heat. Youll be melting seals and blueing bearings to get this one off.

-- #638 would be a good choice. Highest strength but loses almost 50% by 100C.