Greetings all. I am located in Alberta, Canada. We are looking to put a autosteer system on a Versatile New Holland 9480 articulated tractor. It has a 120 l/min pump dedicated to the steering system, Steering side is open centre. Steer rams are 419mm stroke, with 89mm bore resulting in 2.6 l displacement. One ram collapses as the other extends, so to turn stop to stop would use 2.6 litres of oil to extend one ram fully, while the other would retract. So if that would take two seconds, that would be approx. 80 l/min. Is my math correct? What would be an appropriate hydraulic block for this? Thank you for your input.
You are right, they are double acting, so would be a bit less than double the flow I calculated, because of the rod diameter? So its looks like we would need quite a high-flow block, would any suitable non-proprietary hydraulic block be available for that? I forgot to add that this tractor has two hydraulic systems, one is open centre, dedicated pump for the steering, and the other system is a closed centre load sensing for the remotes. Would the entire flow of the open centre system need to go through the valve in this situation?
To calculate the retracting volume:
(Bore Area- Rod Area) X stroke.
If the steering is open center one possibility is to put the autosteer in serie with the orbitrol (most likely before). Then it must handle the full flow, at least in the “priority flow” part, where it take the flow needed by the spool.
If both systems share the same oil tank and you are not limited by the remotes oil demand then using the CC pump seem a good idea to me. Although this would maybe need a steering wheel encoder to desactivate autosteer.
Some people with 4wd tractor could maybe comment about the minimum spool flow required.
Depending what you can source locally the Danfoss PVG32 is popular on OEM and available up to 100L(or even more)
Here is the hydraulic diagram of the steering circuit. It is totally independent of the remote valves. If I would put the valve in series before the orbitrol on the pressure side, the entire flow would have to flow through the block. Would that make the steering difficult if using the steering wheel? Could I plumb it in parallel?
If your steering pump actually gives 120 l pr min, then you might need a flow divider, so not all oil must go through steering valve block. But I find it hard to believe your steering pump gives more than your implement pump which is at 30 gallon/ 114 l pr min.
Maybe make a real life check of what passes through orbitrol.
