Loader downpressure

[wnymudd]

John Deere 3032e front loader functions normally except when trying to lift wheels off the ground for back dragging. It will do it but you have to hold the loader fully forward. You can't just neutralize the joystick like you could when new. New to working on hydraulics. No quick disconnect on this model. Any ideas, adjustments or rebuilds?

 

[Egon]

Check to see if the lift cylinders have any movement left. If not use the curl.

 

[wnymudd]

Plenty of movement on the lift cylinders. Everything works normal and I have downpressure but have to hold the loader control joystick full forward in order to keep the front end up. As soon as I let go back to neutral the front end comes down.

 

[Leejohn]

Pull the cap off on the bottom of the spool, sounds like the shaft for the float detent has come unscrewed for the spool.

 

[SPYDERLK]

I believe JD uses closed center rather than tandem center hydraulics typically used on other tractor systems. Maybe something has malfunctioned in the 'special' setup?

 

[SPYDERLK]

Pull the cap off on the bottom of the spool, sounds like the shaft for the float detent has come unscrewed for the spool.

That would let it out of float. Op is seeing a condition like it is going into float.

 

[Tx Jim]

I believe JD uses closed center rather than tandem center hydraulics typically used on other tractor systems. Maybe something has malfunctioned in the 'special' setup?

According to Tractordata.com a JD 3023E has open center hyd's BUT I think type of hyd's would have no bearing on keeping boom pressured down. I think problem could be internal leaking control valve between spool & housing or boom cyl piston packing leaking.

 

[bigdeano]

I would bet on a piston seal leaking.

 

[wnymudd]

Ok guys thanks for the input!

 

[Leejohn]

Also check if you have a joystick that all linkage is tight and spool movement is the same in and out before the detent for float.

 

[Groo]

Does a heavy weight in the bucket float down as well? If so, not the piston seals, the problem would have to be in the valve at that point.
If thereis a load holding cheack valve in the valve, it might still be a valve problem even if the load doesn't float down.

 

[wnymudd]

It does leak down. About 10 min with the tractor off and it'll be on the ground.

 

[Tx Jim]

It does leak down. About 10 min with the tractor off and it'll be on the ground.

Control valve is leaking internally. Only cure is a new control valve assembly.

 

[SPYDERLK]

According to Tractordata.com a JD 3023E has open center hyd's BUT I think type of hyd's would have no bearing on keeping boom pressured down. I think problem could be internal leaking control valve between spool & housing or boom cyl piston packing leaking.

Ah-h I quess its open center on JD then. ... Open center cannot maintain the fluid in the cyls against force. They would immediately vent to tank. Some other valve -- a piloted check ? -- must hold position. Perhaps that has failed..

 

[Tx Jim]

Ah-h I quess its open center on JD then. ... Open center cannot maintain the fluid in the cyls against force.

Please explain. IMHO OC can maintain pressure against force in cylinder similar to CC if spool valve isn't leaking internally & cyl piston seals are good.

 

[countrybumpkin]

Open center and closed center have nothing to do with holding the cylinders in position when the valve is closed that’s dependent on the type of control valve. Open and closed center have to do with how the fluid and pressure are delivered to the control valves in a system.

 

[Ortimber]

Open center and closed center have nothing to do with holding the cylinders in position when the valve is closed that’s dependent on the type of control valve. Open and closed center have to do with how the fluid and pressure are delivered to the control valves in a system.

Bumpkin is correct. Closed or open center makes no difference regarding the ability to maintain down pressure.

If you have leak down issues, my thought is the valve is malfunctioning.

 

[countrybumpkin]

You’ve not said said anything about seeing any oil leakage anyplace so the valve needs to be looked at. First thing I would do is remove the cover on the top of the valve were the joystick is and also the two return spring cups on the bottom of the valve. Make sure everything is clean and moves freely, it would not take much under one of the centering springs to possibly hold the spool off just enough to cause a small internal leak.

 

[SPYDERLK]

According to Tractordata.com a JD 3023E has open center hyd's BUT I think type of hyd's would have no bearing on keeping boom pressured down. I think problem could be internal leaking control valve between spool & housing or boom cyl piston packing leaking.

Ah-h I quess its open center on JD then. ... Open center cannot maintain the fluid in the cyls against force. They would immediately vent to tank. Some other valve -- a piloted check ? -- must hold position. Perhaps that has failed..

Please explain. IMHO OC can maintain pressure against force in cylinder similar to CC if spool valve isn't leaking internally & cyl piston seals are good.

Open center and closed center have nothing to do with holding the cylinders in position when the valve is closed thatç—´ dependent on the type of control valve. Open and closed center have to do with how the fluid and pressure are delivered to the control valves in a system.

Bumpkin is correct. Closed or open center makes no difference regarding the ability to maintain down pressure.

If you have leak down issues, my thought is the valve is malfunctioning.

Normal loader hydraulics use a tandem center control valve. Load ports are blocked when the valve is centered. This causes the downforce to be held, but pumpflow is routed to tank.​

An open center does not block any port when centered. All ports vent straight to reservoir. These will not hold a load. They are typically used for motor control so the running motor wont be suddenly locked when valve centers.​

 

[countrybumpkin]

Sorry but that’s not correct.

A tandem center valve , for open center circuits , simply refers to that valve type, as being one that as you described as having the work ports blocked and the supply and return connected when in neutral. There are MANY types of valve designs for both open and closed center systems.