Outer Limits 4x4 Board

Being toying with the idea of a pto driven centre mount thomas winch for my HJ47 ute.

I am thinking of mounting the winch in the head board of the tray so I can see the winch spool through the back window. cable runs down through a jockey sheave then to the rear to another sheave and then back through pipe/sheaves to front bumper.

The drive would be from the pto up to a lay shaft on the chassis then a chain drive from the lay shaft to the winch. On either the lay shaft or the winch I'm considering mounting some sort of torque clutch so I can do away with the shear pins. I found this one(.http://tsubaki.com.au/pages/PTUC/torque_limiter.htm) which might work but I need to figure out how many N/m's of force are coming into play.

So questions are
1. Is this idea ok? Am i missing anything?
2.Will a chain be able to handle the force of driving the winch
3.what are the formula's for working out n/m from the line pull of the winch.
4. Are there any other types of torque clutches I can use?

Cant' help specifically, but have had some experience with industrial mechanical torque limiter clutches. Main issue was the time/load characteristics could not be controlled and on some loads that was a real problem. Eventually swapped the more troublesome ones out for "electronic shearpins" where both load and time could be programmed.

Some monitored motor current ( no good to you ) but others used a load cell to actually measure the torque reaction of the gearbox to its mount.

Industrial power transmission specialists would be a good place to start but none of this stuff is cheap.

Have you considered a hydraulic system ? I'm no expert but it would seem easier to implement and load control could certainly be provided.