That’s essentially the David Brown system, double acting ram bolted to the side of the tractor, the drag link operates the valve built into the end of the ram. Personally I like the orbital unit idea, no mechanical linkage between steering wheel and axle, downside is that there is very little feel.One design I toyed with was a double acting cylinder, one end fixed on the drag link, the other to the chassis. The amount of steering input being proportional to the opening of a shuttle valve, a small amount, allowing a small quality of fluid into one end of the cylinder; thus the greater the input the greater the assistance.
For manoeuvring where the input is large the valve opens more, reducing the sweat under the armpits; the usual grimace being transformed into a smug smile
Obviously steering left opens one end of the shuttle giving “up” assistance, turn right & the opposite end gives you the”down“ component.
Operating on the drag link reduces worries about suspension articulation & a shorter cylinder could be used as the throw wouldn’t be as significant.
There has been a significant passage of time between these initial thoughts & now, there is every possibility I could have failed to recollect some salient points, for the most part I think it all hangs together.
M