Spool Valves

[MNBobcat]

I currently have a spool valve mounted near the right fender on my John Deere 3020. Its a closed center system according to the manual. It has 2 control levers on it -- lift and tilt.

I want to add 3 more for a total of 5. If my spool valve accepts a power beyond, is it just a matter of adding the additional spool valve having 3 levers or alternatively do I swap mine out for a 5-way? I'm not quite clear on how these work. For example, I need to be able to lift the FEL and have it hold position while operating another lever for a hydraulic vibratory motor which would take a constant hydraulic flow. Does the spool valve hold pressure to the front end loader while providing additional flow to the other ports to operate other cylinders/attachments?

 

[kennyd]

Power beyond is only used on open center systems. Each spool will hold the load independently of what the other spools are doing. Just for neatness, I would probably just build a new 5 spool stack so you can customize each spool as needed, like having float on the lift/lower circuit and using a motor spool for your vibrator (that doesn't sound right does it )

 

[MNBobcat]

Power beyond is only used on open center systems. Each spool will hold the load independently of what the other spools are doing. Just for neatness, I would probably just build a new 5 spool stack so you can customize each spool as needed, like having float on the lift/lower circuit and using a motor spool for your vibrator (that doesn't sound right does it )

Hey, don't you be talking about another guy's motor spool like that! LOL!

Thanks for the reply. That helps.

If I understand correctly, its the spool valve that dictates if its open center or not, correct? If so, if I build a new spool stack would I want to set it up with an open center? In the past there are things I had thought about doing but the whole open/closed center thing caused some concern.

 

[J_J]

An open center hyd system is the combination of open center valves used with a gear pump that run all the time, and all valve are in series.

A closed center hyd system provides standby hyd pressure in some cases, and very little work is done until the closed center valves causes the pump to fully stroke the hyd system and supply full hyd power.

Closed center valves are also in parallel.

You normally can not mix the two hyd systems.

If your tractor hyd system is closed center, then use closed center valves.

Some hyd valves are convertible by adding a closed center plug.

just get another set of valves and use a detented spool to provide constant flow to the hyd motor.

Remember, all valves are in parallel. Just tee off the pressure supply line and install and run the tank outlet to tank.

 

[kennyd]

Mainly it's the type of pump that dictates OC or CC, since your current system is CC you'll have to stay with that, so all new valves must be CC.

What's the flow and pressure ratings for your machine?

 

[MNBobcat]

Thanks guys, I got it now. Its 18 GPM at 2250 PSI. The vibratory motor only requires 4 GPM and 1200 PSI. So I'll be installing a flow/pressure regulator at the vibratory motor to keep it within spec of the vibratory motor capacity. I may be running some additional hydraulic rams which is why I'm considering 5 valves total on the tractor.

 

[Tx Jim]

It will surprise me if a 3020 has 18 CPM hyd flow but I have no 3020 tech manual. One needs to be careful not to cavitate front hyd pump while trying to operate an orbit motor on the CC hyd system but the added flow regulator will help control heat. Also overheating hyd system can be a problem so be sure hyd oil cooler is CLEAN. I agree on mounting a 5 spool CC valve.

 

[J_J]

JD 3020

Hydraulics:
Type: closed center
Capacity: 4.5 gal [17.0 L]
Pressure: 2100 psi [144.8 bar]
Valves: 1
Total flow: 18 gpm [68.1 lpm]
23 gpm [87.1 lpm] (4WD)


Steering could use some of the total.

 

[Tx Jim]

J_J
Tractordata has been known to contain some misinformation. I'm in no way picking on TD as it contains a wealth of valuable information!!!!!!!! Two items in the 3020 spec's I know for positive are incorrect are the pressure @2100 psi(should be 2250 psi) and 4.5 gal cap(should be 10). Compare those spec's to the 3020's big brother of the same era the 4020 and notice the differences in spec's. One set of spec's is incorrect and I think it's the 3020(retired JD dealer service manager's opinion). IIRC the 3020 shares the same hyd pumps & hyd reservoir with the 4020.
Hydraulics:
Type: closed center
Syncro-Range Capacity: 10 gal [37.9 L]
Power Shift Capacity: 12 gal [45.4 L]
Pressure: 2250 psi [155.1 bar]
Valves: 1
Pump flow: 13 gpm [49.2 lpm]

 

[J_J]

I agree there are inaccuracies in some data.

If you know better, then please correct tractor data info.

I have seen this on whether the tractor is an open center or closed center.

So one has to use what is available.

Please feel free to correct anything not in order.

I would actually measure the pressure and do a GPM test.

Is this list any better?

https://jdparts.deere.com/partsmkt/...b_HydraulicPumpSelectionGuide.htm#_JOHN_DEERE