Hydraulics questions

Paddy · Sep 9, 2005

I have an old BH that needs to be reworked. The control valves for the our stabllizers have replaced with a seperate set on a different circuit /forums/images/graemlins/crazy.gif

The rest of the control valves look like they could go at any time. I have a Northern Tool catalog with a section for Prince Control valves. These are sectional control valves. That is you take the required set and bolt them together. This is how the BH is now.

Questions, They use terms like;
3-Way, 3 position and spring Centered
4-way, 3 position and spring Certerened
4-way, 4 position, Spring centered and Detent Float

What kind do I need for the stablizers(2)??
What kind do I need for the other BH fuctions(4)??
The 4 valves that operate the dig fuctions each control one cylinder except the one lever that controls swinging the bucket left or right.

The BH has 2 levers for the stablizers. And 2 levers for the dig fuctions. the dig fuction levers control two valves each. They move For-Rev and side to side.

Patrick

Bigbear · Sep 9, 2005

I'm no expert Paddy, but I will try and answer a few questions the best I can.
Stabilizers would have a double acting cylinder and use a 4way3position spring center. This valve has 1 inlet, 1 outlet and your 2 working ports that would go to the cylinder.
The other dig functions are the same in that they use a double acting cylinder also.
Some boom swings use single acting cylinders and some use double acting. A single acting cylinder will only have power in one direction, and rely on weight or another cylinder to push it in the other direction. This would take a 3 way, 3 postion valve.
I believe ones that use 2 double acting cylinders (power both directions) are plumbed so they work at the same time, one goes in and the other goes out, or makes the boom go right and left.
I have bought many hydraulic parts from NH and I don't think they have a joystick or 1 lever operating 2 valves, offered. Hope this helps, and I'm sure some of the other guys can give you a better understanding than I can. /forums/images/graemlins/grin.gif

JerryG · Sep 9, 2005

Patrick,
What would seem like the best thing that you could do is get a valve from the Surplus Center . They have complete backhoe valves. You need to look for one that has the right gallons per minute and also know if it is open or closed center.

Paddy · Sep 10, 2005

The valve on my BH has the "stack" of valves with end sections where the fluid comes from the pump and returns. Is that open center?

Patrick

JerryG · Sep 10, 2005

It could be either open or closed. I would call that place and speak to them. They are very helpful.

kennyd · Sep 10, 2005

Why not take the whole stack to a local hydraulics shop and get a price for fixing these up?

Is this hoe a 3PH model, or self powered unit? That will help up determine whether it is a open or closed center system.

Paddy · Sep 10, 2005

It's a Ford 758 BH. It has been modified from original but the controls look original, (except the stabilizer's control).

It has a Prince PTO pump.

What reason for open center/closed center?

I do have one of the old sections that I could take to a shop.

Thanks for your help,

Patrick

MadReferee · Sep 10, 2005

The PTO pump would indicate that you have an open center system since the pump would always be pumping.

It would probably be to your advantage, price wise at least, to go to Surplus Center and purchase a complete new valve with all the spools you need. The cost for a hydraulic shop to repair or replace a spool would most likely equal or exceed the cost of a new valve and spools.

Paddy · Sep 10, 2005

The issue about 1 lever controling two valves. It's a nice design. There are shafts, in the shape of a Tee. For forward and reverce motion of the lever, the stem of the Tee rotates. This operates one valve. Now with the same lever you can go side to side by rating on the top of the Tee. Thus two levers control 4 valves.

The linkage has been repaired be for and is a bit slopy. I will need to redo that as well. The pivit Tees are just fine and will work around them.

I called NH and they wanted $600 for each valve in the stack! That is why when I saw the Northern tool catalog with each section of the stack at $60, I said I can replace the entire set. I would need to get the end sections as well.

I will clean it off so I can see how the two cylinders that op the swing are plumbed. Can I assume if the cylinder has an in and out port, it will be a two way type?

Patrick

Bigbear · Sep 10, 2005

Paddy, I believe that is correct. The only single acting cylinders I have are on my old snow plow for the Jeep, and all three have only one hose going to them. Right, Left, Power up, and gravity down.