Inspired of the talk of castors in Yahoo Gravely club
I gave them a try, and here are the result.

This test consist of: Two used castors, two M20 bolts and two M20
locking nuts and two pieces of steel.

So far it is working! How easy it is to do sharp turns now!

The Belleville-washers

Auger and friction disc

Gear and hexaxle

The fan

The Glove which performs, "a magnificent
plume of soaring snow"

Gear and auger assembled again.