Articulated mini tractor

I intend to put auto steering on a MacTrac. It’s to be used in fields for sowing and weeding in vegetables so I need a high precision system.

Before I start to build I want to check with you guys on the steering part. I want to use hydraulic steering. It’s using a hydrostatic steering unit from M+S Hydraulic (HKUS40/4). It’s Open Center - Non Load Reaction. I’ve been reading all I can find on these forums but I can’t find a clear answer to what I need to get this working. The Wiki suggests a Savery SP10-47C, but I’ve seen arguments that this would not work alone but you would need another valve to “turn off” the manual steering?

Has anyone here used the Savery SP10-47C with an Open Center - Non Load Reaction steering module? Are there any alternatives to Savery (that does not have 112 days of delivery time) that you could recommend?

Such a small tractor should be fitted with a valve that can pass oil at max about 3L / min or even lower. The SP10-47C has a maximum oil flow of 22L / min, which is too much even for a tractor of 160hp 6.5ton. Large valve works too, but requires strangulation of the flow, and then sensitivity is lost.

Thank you for pointing this out. Any idea where I could find a valve with lower capacity? The Savery SP08-47C has a maximum flow of 11 lpm. That’s the smallest valve I can find from Savery…

This Cetop 03 valve is available with 5L/min spool. Don’t know any smaller, but please let us know if you find one.

Thanks! I’ve reached out to a couple of makes. We’ll see if they respond.

They have this one also:SP08-47CL 7.6 lpm