Stacking OMCO Hydraulic Valves

[oliver2-44 9,739]

Some WH tractors with Sundstrand transmissions use the OMCO hydraulic valve.  As I mentioned in another topic, these valves can be stacked together.  @pfrederi @Handy Don @ebinmaine

My 1974 C160 originally came with 1 OMCO valve. I have now stacked two of them together.  The 2nd one came from a C-120 parts tractor.  I took them to a hydraulic shop and matched up O-rings to rebuild them internally and O-rings to stack them together.  

T

Below is an stacked OMCO dual valve from a C195 that I got from A-Z.. The valve on the left is the same as on my C160, The valve on the right with the longer tail piece has the float function.

You could stack as many valves as you wanted between the two outside plates.  You would just need 3 longer 1/4" bolt to hold them together, and more O-rings.

I think some Gt-14 and maybe some D series tractors used the OMCO valves.  But I've found WH also used different brands of valves on some of those tractors.

This shows the bottom side of the stacked valves from the C-195.

Here is a parts list 

 

 

Here is the Wheelhorse Hydraulic Valve and Cylinder Manual

WH Hydraulic Valve and Cylinder Repair Manual.pdf

 

 

Hydraulic Lift valve and Cylinder Overhaul - sundstrand transmission.pdf

Edited January 16 by oliver2-44

[case442 130]

I have a C195 setup with the lift cylinder available. Sewickley Pa. 15143

[Handy Don 12,214]

1 hour ago, oliver2-44 said:

Some WH tractors with Sundstrand transmissions use the OMCO hydraulic valve. 

Glad to be corrected! Great to have those stacking valves to extend to another circuit. If I’d had those on the 520 it would have been a lot easier to add more circuits!

.

Just a note that the WH valves I’ve seen are not open center--open center valves will not hold a cylinder in a set position, e.g. with the mower deck or blade raised. Essentially, the center position of the control becomes “float."

They are tandem center where, when the control is centered, the P (pump) inlet on the valve is directly connected to the R or T (out or tank) port but the A & B working ports to the cylinder are closed. 

Can the stacked valves you showed operate simultaneously, e.g. drop and curl together, or must you use one at a time?

[case442 130]

[oliver2-44 9,739]

2 hours ago, Handy Don said:

Glad to be corrected! Great to have those stacking valves to extend to another circuit. If I’d had those on the 520 it would have been a lot easier to add more circuits!

Note the 2 manuals are slightly different and cover several valves.  You have to pay attention to the manufacture code # on the valve because OMCO valves made for the Sundstrand transmission do not have a relief valve and use the Sunstrand relief. OMCO valve smade for the Eaton 1100 HAVE  an internal relief valve.  So I interpret this as do not use an OMCO Sundstrand valve on an Eaton, but I suspect you might be able to us a OMCO Eaton valve on a Sundstrand.  On this later setup you would have 2 relief points ( Hydraulics sure can get complicated)

 

Just a note that the WH valves I’ve seen are not open center--open center valves will not hold a cylinder in a set position, e.g. with the mower deck or blade raised. Essentially, the center position of the control becomes “float."

They are tandem center where, when the control is centered, the P (pump) inlet on the valve is directly connected to the R or T (out or tank) port but the A & B working ports to the cylinder are closed. 

Can the stacked valves you showed operate simultaneously, e.g. drop and curl together, or must you use one at a time?

 

I have not installed/used it yet, but from what the repair manual says, the OMCO valve with the long cone on the end has a detent and will lock in the Float Position and easily release with movement of the handle to lock the cylinder in place.  So when moving the valve handle there is a normal center position which I read as being Tandem operation, then i move it and I can feel the detent where it will hold and be in the float position. if i keep moving the handle it continues to the down position. 

 The 2 shorter style OMCO valves as shown on my C-160 are Tandem .  If you try to use them together the one on the pump side of the manifold works full speed and the 2nd one creeps. Almost like its not supposed to move, but a little leakage is happening.  So I would say you cannot  drop and curl at the same time.

 

[Handy Don 12,214]

9 minutes ago, oliver2-44 said:

 

Thanks for taking the time to clarify.

Yep, the float position is interesting plumbing.

 

Some simply connect the A and B ports that go to the cylinder and disconnect P (pump) & R (reservoir). Less than ideal because the oil volume on the two sides of the piston are different and so float has a lot of resistance and stresses the piston seal.

 

Some connect A&B and also P but since the piston area is larger on the extend side than on the retract side, the piston wants to extend more than retract making it an uneven float.

 

Many (most?) connect A&B and also R so that if the cylinder needs more oil (rod is extending) it’ll pull it in from the low pressure side. I’ll guess this is the OMCO stacked valve behavior and they want the float spool to be away from the pump so the regular spool can be operated while the float spool is in float. (This is how the JD valve I’m using from a 425 works.)

[wallfish 16,994]

3 hours ago, oliver2-44 said:

open center valves will not hold a cylinder in a set position, e.g. with the mower deck or blade raised. Essentially, the center position of the control becomes “float."

? I used open center valves on the hoe build and they hold cylinder position just fine. So do the loaders.

Closed center valves are used for variable displacement pumps and will not work for a fixed gear type pump. (Like the Cessna FEL pump is) It closes off to the pump so a gear pump would continually build pressure. A variable pump will stop building pressure. At least that's my understanding of it. Maybe the trans Hydros are variable type

Edited January 17 by wallfish

[Handy Don 12,214]

12 minutes ago, wallfish said:

I used open center valves on the hoe build and they hold cylinder position just fine.

I, too, encountered this so I researched it and got schooled.

Some makers of directional control valves call them open center with check valves to hold the cylinder. Technically, that’s a Tandem!

The Regenerative is interesting because it assumes that if the cylinder is being forced to retract, the fluid returns to the pump side of the circuit.

 

Edited January 17 by Handy Don