josh wrote:

What this looks like to me is, another method of increasing the line pull for the blade lift rather than using the multi part block used on most cable blade lift assemblies.
It looks like the cable coming off the CCU attaches to the larger sheave, and the blade is connected to the smaller one, notice there is not the usual two part block assembly used to accomplish the speed reduction and increase power to blade lift.

Is it possible that another reason for the strange configuration is to prevent "trash" like wood chips from getting into the conventional block lifts from chips etc spilling over the top of the blade?  No dirt and pieces of rock, chips or whatever wearing cables and pulleys with the single strand of cable attached to the blade..
Just a thought!