Hydraulic proportional directional valves seem expensive and electric motors in the cab aren’t simple either and add noise.
Has anyone used other steering control methods such as adding an electric over hydraulic pump to the steering lines? Our combine has symmetrical steering cylinders so we could just pump oil from one line to the other and vice versa to steer the wheels using a reversible/bidirectional hydraulic pump/motor.
How about adding a closed center steering valve to the circuit powered by an electric motor? Again, adding/dumping oil to the steering lines using the on board closed center hydraulic pump for header lift/tilt auger swing etc.
Pricewise new Danfoss 125 size orbitrol should be somewhere in the ballpark of 5-600 € VAT 0%. Add the motor, piper, gears I’d say it lands around 700-800 €.
I think @baraki built the hydraulic system well under 1000 € with Cetop valves, I was around 1300 € with the PVG16 and hoses.
Of course sourcing a second hand orbitrol is a lot easier than to find a specific size of a propo valve.
This is my idea from over half a year ago! I also tested this solution on my own and it works fine. Danfos orbitrol is expensive but a replacement for the OC system can be purchased for as little as 50 EURO. For the LS it is already 3 times more expensive and with the addition of the engine, the price approaches the proportional valves.
If someone decides on such a solution, you can disassemble the orbitrol and remove the leaf springs that generate the steering resistance, then a small motor with a small torque is enough to control.
If your tractor has canbus control spool valves - assuming you could figure out how to control- could you use this for steering by simply ting the steering lines into the spool.
Two orbitrols connected in series.