Can I run power steering from tractor hydraulics?

NormL · Jul 29, 2011

I have an Oliver 550 with hydraulic steering. This was a conversion done before I acquired it and it would seem that the conversion was done this way because the steering box wore out or otherwise became unusable. The pump driving the system right now is an automotive power-steering pump driven by a skinny little belt. The way the belt comes around to all the functions it serves leaves very little of that belt running on the pump pulley and as a result the belt needs to be drum tight. Changing to a heavier belt would mean modifying all the pulleys on that circuit starting with the crank pulley - not a pleasant task!

My question is this: since my tractor hydraulics are driven from a pump mounted in front and driven from the crank, could I tap into the output side directly and simply use that as my supply to the hydraulic steering?

J_J · Jul 29, 2011

You could probably do it, and I would suggest a flow divider/priority circuit to always give the steering some fluid to use for steering.

So if your current pump is a 8 GPM pump, then you could get a 2 GPM priority valve and connect to the steering. The other flow out of the priority circuit could be used for the tractor hydraulics such as a FEL, or 3pt.

Something like this

http://www.surpluscenter.com/item.asp?item=9-4158-15&catname=hydraulic

http://www.surpluscenter.com/Instruct/I9-4158-15.pdf

NormL · Jul 29, 2011

J_J said:
You could probably do it, and I would suggest a flow divider/priority circuit to always give the steering some fluid to use for steering.

So if your current pump is a 8 GPM pump, then you could get a 2 GPM priority valve and connect to the steering. The other flow out of the priority circuit could be used for the tractor hydraulics such as a FEL, or 3pt.

Something like this

Surplus Center - 1.5/30 GPM PRINCE PRIORITY FLOW DIVIDER W/RELIEF

http://www.surpluscenter.com/Instruct/I9-4158-15.pdf

Thanks J_J. This tractor has the FEL and it is served exclusively by the hydraulic pump. That is why I'm hoping there is enough capacity in there to allow for the power steering. Correct me if I am wrong; unless there is a device such as the divider/priority valve in place, the flow of hydraulic fluid would tend to concentrate where there would be the least resistance. That would mean that unless the free flow of oil was restricted from the spool valves, there would be little, if any, assistance when I try to steer. Is that correct?

J_J · Jul 29, 2011

The way a priority valve is used is, from pump to priority valve, and then one metered port would go to steering. The rest of the available fluid would exit the valve and go to FEL. So if you had 9 GPM, and the priority had 2 GPM for the steering, then 7 GPM's would be available for the FEL and 3pt.

If the tractor should be running very slow, the steering would still get the 2 GPM, but the FEL might only have 4 GPM's available, since pump rpm dictates the flow in GPM's.

Priority valve flow to steering circuit is necessary, to always have steering.

Taylortractornut · Jul 29, 2011

What JJ Described is exactly how our little AC D grader at work is set up on the steering. We took the steering valve off a Hyster fork lift and the cylinder as well and mounded it on the grader. We used a Priority valve for this and it works like a charm.

NormL · Jul 29, 2011

OK; does this item available near where I live look like what you gentlemen are referring to?
http://www.princessauto.com/power-t...stable/8252777-16-gpm-adjustable-flow-control It is given a different name than the one you showed me, J_J. When I did a search for a divider/priority valve on the PA site, it did not recognize the wording so I dug around on the hydraulics page and found the flow-control device. There is also an adjustable line throttle valve shown there but I don't think that would be any help.

J_J · Jul 29, 2011

No, that is a flow control valve. It is used to control the speed of a hyd motor. You need a valve that will separate the flow into different flows in GPM, with priorityflowgoing to the steering. .

What I posted above is what I think you will need.

This page has a lot of priority flow divider valves. Power steering doesn't require very much flow, and it should have relief valve.

http://www.surpluscenter.com/sort.asp?catname=hydraulic&keyword=HADI

NormL · Jul 29, 2011

J_J said:
No, that is a flow control valve. It is used to control the speed of a hyd motor. You need a valve that will separate the flow into different flows in GPM, with priorityflowgoing to the steering. .

l]

I think I have it now! It turns out PA no longer handles that product, more's the pity.

Getting one shipped here from Surplus Center or any other supplier in the USA gets pricey real fast. I guess this will have to wait till my friend the charter bus driver does his next trip to Chicago and I can give him a shopping list.

In the meantime I guess I'll just have to spring for a new belt and some belt dressing and do the best I can. In a couple more days my hay will be ready to bale and another field needs to be cut so I can't have that tractor down!

BTW, where is the Surplus Center located or are they an Internet/mailorder only shop?