Old two spool control valve (very slow)

[nsmithnd]

Does anyone recognize this two spool control valve? It was on the garden tractor when I got it (obviously an add-on). One port was blocked off and the other was used in place of the original "lift" control valve on the garden tractor. I found a replacement control valve for the "lift" and used the dual to add quick disconnects to the front and rear. I used the front quick disconnects for about a year as a snow-blade angle control with a dual acting cylinder. All worked well until the cylinder started acting up (or so I thought). Had the cylinder rebuilt and same thing (very slow to react). Tried a different cylinder with the same results. Would it just be the relief valve opening up too soon? Since it used to work and suddenly didn't any more, I'm guessing a broken spring or seal gone bad maybe? Haven't tried taking it apart yet, was hoping there might be a diagram out there somewhere. Oh... the garden tractor has two other control valves (singles) in series with this dual and they still work fine, so I know the pump is still good.

Thanks
-Neil

 

[J_J]

How about some pressure readings?

What is pump pressure?

Is reservoir full?

What pressure does the relief activate?

Does the cyl extend or retract due to static weight. Seals could be bad.

Max out the cyl and tell us the pressure.

Check the QD's for correct operation. QD's plugged together does not necessarily mean they are good.

 

[wdchyd]

That's a Cessna control valve........the pressure relief valve spring is under that non-adjustable cap....

best to get a hyd guage to find out the pressure setting, then take apart the PRV and inspect the spring and poppet......to increase pressure a shim may be needed (installed between the spring and cap)

 

[wdchyd]

Sorry, forgot to add the pics

 

[nsmithnd]

Thanks for the responses. Busy work week this week (on-call) so probably won't be until next week that I'll get a chance to tinker with it and get some pressure readings.

-Neil

 

[nsmithnd]

Rigged up a test fixture and got around 750 psi during travel and 800 psi when the cylinder dead-ended. Removed the cap and verified that the spring is still in one piece. Should the poppet have slid out with the spring (can't find the parts diagram I downloaded - grrrr)? As for shim(s) are we talking dime, penny, or nickle thickness?

Thanks
-Neil

 

[J_J]

What is the pressure on the pump? You have to know this to set the correct pressure for the relief. If it takes the shims, they are real thin.

This an example of some shims.

Three sizes of shims came in this pressure kit. one .1mm, two .2mm, one .3mm

1 mm = 0.039370 in

2 mm = 0.078740 in

3 mm = 0.118110 in

If you use the whole pack, it will be

8 mm = 0.314960 in

A dime is 1.35 mm = 0.053149 in

A nickel is 1.95 mm = 0.076771 in

A quarter is 1.75 mm = 0.069 in in

Use only one , or combinations.

 

[nsmithnd]

I won't be able to get readings at the pump any time soon. It's too close to snow season to start tearing into my spaghetti mess. I'm wondering if 800 psi is all I've got through the whole system (pump is part of the Eaton 12 hydro unit on the Bolens).

From the hydro it goes directly into an add-on control valve that is mounted under the seat-pan (controls the 3-pt hitch). Then on to the dash-mounted control valve (controls the deck lift), and then on to the dual control valve to the left of the dash (front and rear aux quick disconnects) before dumping back into the hydro. The two Bolens control valves are connected to standard dual-acting cylinders (2" bore x 6" stroke). I've re-tested both front and rear aux with an extra dual-acting 2" bore x 3-1/2" stroke cylinder, and with no-load it seems plenty fast both front and rear.

Maybe my snow-blade angle configuration (a pair of single acting cylinders) is just too much for it.

SPECIFICATIONS
Single Acting
Bore x Stroke 2-1/4" x 5-11/16"
Pressure 3200 PSI max.
Rod Dia. 1-1/2"

My guess is that the pressure relief on the dual spool isn't even activating (if there is only 800 psi to work with). Or maybe I've just got too much air in the cylinders. Or all of the above?

Either way, I'll probably just grease up the plates at the pivot point and loosen it up as much as I dare, and try bleeding the cylinders again.

Thanks
-Neil

 

[wdchyd]

nsmithnd,

We have been working on a similar unit last week and eaton (1100 series) recommends a relief valve 800 psi max......that's all that front geroler pump (aux pump) puts out comfortably....(500 psi standard....800psi optional)

http://hydraulics.eaton.com/products/pdfs/E-TRLD-TM001-E.pdf

Check out page 13 on this pdf

You may have another model of pump but this one I'm familiar with.....look under lever area for stamped numbers in alum housing

Hope this helps....:thumbsup:

 

[nsmithnd]

I was just digging through some downloaded Eaton 12 service manuals and various on-line info and came across the following.

The Eaton would only have 1-1/2 GPM at about 5-600 PSI.

Aux pump performance 3 GPM @ 3600 RPM, Free Flow
1 GPM @ 2000 RPM, 500 PSI

And the Eaton 11 info on the Bolens large frames showed the same as what wdchyd provided in the previous post (thanks wdchyd) 500 - 800 PSI.

Service manual test for the lift cylinder measures between the control valve and cylinder and reading is taken when the cylinder max's out. Anything above 450 PSI is acceptable.

If I'm measuring 750-800 between the aux quick disconnect and the cylinder when it max's out, does that mean I need to remove shims to allow the control valves relieve valve to kick in ? Would that help the cylinder performance (or at least allow the pump to be less stressed) ?

Thanks
-Neil