Adding power steering - why a separate pump?

[rectifier]

3 GPM at 3600 rpm.

That's not very much! How much flow are you dedicating to the steering, then?

With my 6GPM pump I still find my hydraulics are pretty "slow" though I do tend to run the machine at half or lower throttle unless I'm actively using the PTO or in a hurry to move a lot of bales.

 

[J_J]

My total flow goes through the steering valve and uses as much as I turn the wheel, and can take all flow.

When not steering, the steering valve passes all flow to the loader through a PB port.

The size of your cyl and GPM will dictate speed.

 

[Egon]

Find out what flow your tractor has and what flow the new steering system requires. That will let you decide on which way to go.

 

[bigdeano]

I don't know anything about those steering valves, but do you know if the port that goes to the tank will take a lot of back pressure? If you were to put it first in line with your other valves it would have to withstand full system pressure on the tank port. You may blow out the seals.

When I built my homemade garden tractor I used a car steering gear inline with the other valves, but I had to put the steering gear last because the seals on the input shaft are low pressure. I can't steer when I operate the hitches, but I can live with it.

Edit: Does your valve have a PB port like JJs? . If that's the case then it should work fine first in line.

 

[rectifier]

Valve with PB port would solve all the problems it looks like. I'll have to examine the ones in the old combines but suspect they ran off of their own pumps. They only have 4 ports, I know that for sure.
PB would always be a fifth port I assume, with a regular tank port as well?

Project set aside for now, been a big rush to bale up the hay before the storm comes tomorrow.