Hydraulic expertise (Gator) welcome

[vatreefarmer]

I just came home with a new to me 2016 825i JD Gator. One option that I sought out was the hydraulic dump bed. I bought it from a JD dealer in NC. As a used piece I did not expect any sort of warranty. Everything functioned fine during my test drive. However I now have run into an issue.

The hydraulic bed lift opens absolutely perfectly when raised, but will not lower. When switch to lower is depressed, I can hear the solenoid activating and pump functioning. If left to sit for a half hour or so, I can lower the bed a few inches by hand, as if hydraulic pressure holding it up has leaked down a little. After a little research it sounded as if the issue is a stuck check valve for the down position. So I disconnected the hyd cylinder from the bed, found the little pressure release screw and backed it out allowing me to manually compress the cylinder all the way to close. While still disconnected from the bed I functioned to unit and it worked in both directions! Feeling proud of myself for isolating problem and getting the valve unstuck, I reattached the lift cylinder to the bed and smiled as the lift worked perfectly in both directions!!! My smile ended the following morning. The same issue returned and my previous method of getting it unstuck did not seem to work. I now need to replace the down check valve.

So heres my issue. JD does not sell the faulty check valve by itself, they only sell a complete hydraulic unit and it is $780!!. I was able to discover that the hydraulic unit is made by KYB and marketed under the "mini-motion" self contained unit. So I called KYB hoping that they would sell me the valve. But they will not. They tell me that the unit is proprietary and I will have to purchase all parts from John Deere. When I tell them that JD will not sell me just a check valve, they can offer me no further assistance.
The dealer I purchased it from is aware of the issue, and the salesman told me to "hold on" as he checks into ways to resolve the problem.
Below is a link to the unit manufacturers site. It honestly seems to be a $5 part preventing me from being able to use the machine as I intended. But I cannot seem to be able to locate or purchase the part.'
https://www.kybfluidpower.com/produc...otion-package/

[vatreefarmer]

I have already contacted a local hydraulic repair place, but they tell me that they only repair cylinders and check valves aren't in their wheelhouse

[Axkiker]

Does the check valve have a part # on it ?

So since you are looking to replace just the part have you taken the valve off and tried cleaning it then reinstalling?

[Axkiker]

I have already contacted a local hydraulic repair place, but they tell me that they only repair cylinders and check valves aren't in their wheelhouse

Also have you called a place like Parker. They have pretty much anything hydraulics related.

[Dropdeadfred]

trying to rap my head around this without looking at it, or a hydraulic and electrical drawing. But sounds to me the check valve is doing what it is suppossed to be be doing.. Namely "Checking" the flow and holding it up,, eventually minor leak by allows it to lower.
Does the thing actually power down ? or does it just blead off fluid and allow gravity to lower it like a bottle jack does ?

I am thinking what you have is a counter balance valve issue.. IE a checkvalve with some kinda actuated bypass valve and line that goes around the check valve when you flip a switch or turn something. Havent looked at it, but it could just be one assembly with orifices, or a simple direction control valve, (DCV) any way you can get the drawings ? Its the bypass that isnt functioning.

As far as the parts, I strongly suspect KBB is just assembling things, some times you have to go backwards up the supply chain to find the MFG of the components. Googling the part number, Googleing the name of the part then search images... You can then find an image that looks like your part. Ive done this more times than I can count on appliance's , furnaces, propane fire places, Most end item mfg are simply parts assemblers. They dont actually make anything.

[vatreefarmer]

Yes, the check valve is in fact doing what its supposed to do. I'm no mechanic or well versed in hydraulics. I am just assuming that it is sticking closed. To answer your other question, the unit does power contract (close).
But with your theory, where should I begin?

[188Musky]

Yes, the check valve is in fact doing what its supposed to do. I'm no mechanic or well versed in hydraulics. I am just assuming that it is sticking closed. To answer your other question, the unit does power contract (close).
But with your theory, where should I begin?

Can you remove the check valve, and clean it up?

[larryhyco]

I was a engineer for Parker Hannifin fluid power many years ago. It sounds like a check valve in the system somewhere. Find it and clean it.

[JAZII]

Yes, the check valve is in fact doing what its supposed to do. I'm no mechanic or well versed in hydraulics. I am just assuming that it is sticking closed. To answer your other question, the unit does power contract (close).
But with your theory, where should I begin?

coil or pilot part of check valve is bad

[CJ1]

I believe what you are calling a check valve is actually a 2 way poppet valve. Look on the nut and there should be info on that that will identify the cartridge valve. If it is a cartridge style valve and most inexpensive systems are then pull the top nut off and remove the coil to be able to see the info on the valve wrench flats. If the cartridge valve gets damaged or sticks it usually burns the coil out, don't replace a bad coil unless you find out why it failed. Cj

[jbrew73]

Look at the “download the catalog” link. The issue would likely be the pilot operated check valve or the slow return valve orifice. I’m not familiar with that assembly but the parts could be external or you could have to remove the oil reservoir to access them.

[Crappie Bob]

Worked on a lot of different hydraulic systems over the years but been a while. My guess would be number 4 or 5 in your diagram. They are the main controllers. It also shows number 6, manual release valve for emergencies, carefully open it, use a prop under the bed, and see what happens.

[vatreefarmer]

Worked on a lot of different hydraulic systems over the years but been a while. My guess would be number 4 or 5 in your diagram. They are the main controllers. It also shows number 6, manual release valve for emergencies, carefully open it, use a prop under the bed, and see what happens.

Yes, I used that approach for my initial "fix." I simply detached the bed from the lift and turned the release valve enough that I could compress the cylinder by hand back to closed. I was able to briefly get the unit to function (both up and down) properly even under load. However most of this unit is self contained and I'm not sure I can even access the check valves without breaking it even more.

[vatreefarmer]

Look at the “download the catalog” link. The issue would likely be the pilot operated check valve or the slow return valve orifice. I’m not familiar with that assembly but the parts could be external or you could have to remove the oil reservoir to access them.

Thanks. Thats why I included that link in the thread. I shows that there are 2 check valves in the system, but they are relatively inside the unit. It seems that the unit is trying to work properly, ie it is receiving the power from the switch and pump turns on. I was hoping that maybe there might be a wire that actuates the check valve that might be loose, but my guess it that circuit is actually internal.

[Roddy]

The check valves are pilot operated. There won't be a wire to them. They operate on hydraulic pressure and seldom stick closed unless the system is dirty ans when it sticks it normally doesn't allow movement in either direction

[vatreefarmer]

20201025_114157.jpg
Yes, that makes sense. The entire wiring harness to the unit only has two wires.

[jbrew73]

Assuming that the polarity is flip flopping on the power wires when you raise and attempt to lower, the problem is mechanical and not electrical.

[suck my wake]

We have three Gators. A twenty year old six wheeler, a fifteen year old HPX, and last week just bought a XUV 825. All three have dump beds. I just looked through the owner’s manual but all it really says is don’t keep holding the switch down after it fully raises or lowers.
We’ve never had an issue with our dump beds. I can check with my dealer tomorrow and at the least I’ll get an honest answer for you.

[DABS]

My tractor does that but only when it's low on hydraulic fluid....just sayin

[vatreefarmer]

My tractor does that but only when it's low on hydraulic fluid....just sayin

Wouldn't that give an issue in both directions? I'd be ecstatic if the issue is that simple, but the unit does lift, which should be the greater of loads on the cylinder. It won't even retract if unattached.