3 Point Hitch slow and unintended dropping

[The Gaul]

Need some help getting to the root cause of my 3 point hitch dropping slowly and unintended.

Tractor : Kioti NS6010 Hydrostatic transmission, 60HP

Symptoms : 3 point hitch drops slowly when it is loaded with the weight of e.g. my flail mower. Over about a quarter mile of riding it will go from top position all way to dragging. This never happened during my first year of ownership.

Additional important data points :

• As said, it happens slowly. When I engage the locking knob on the hitch control lever (when set in the highest position), I can prevent the hitch from dropping at all. This leads me to assume that not a lot of force/leakage is involved.
• I installed a third function up-front. No leaks and no such spontaneous dropping on the FL.
• I also installed a set of extra valves in the back. Upon activating them the first time I blew a small rubber gasket where the additional valve unit was clamped to the OEM one. This resulted in hydraulic fluid spraying all over the place. Most probably the rubber gasket between the 2 valve units got pinched, causing a leak. Anyhow, I was able to fix the issue by installing a new gasket. No more leaks. Having said that, the dropping started somewhere around the time-frame where i added the extra set of valves.
• Both primary and secondary valve set in the back work fine, as tested with a flail mower which needs both sets. No leaks.
• Hydraulic fluid is at the appropriate level

I investigated these symptoms through an on-line search and in most cases there is some kind of a hydraulic leak involved. To the best of my knowledge, I have zero leaks. This has been confirmed both through visual inspection and checking the level of my hydraulic tank.

Can anybody throw me a bone ?

 

[ptsg]

There is a knob under the seat, that adjusts the speed the 3 pt drops, or if fully closed, locks the 3 pt in place. Still lets it raise at any speed though.

Do this simple test to rule out bad piston cylinders on the 3 pt hitch cylinder. Raise the 3pt to max height, turn the knob so it locks the 3 pt in place, move the 3 pt lever to the lower position, shut down the tractor and let it sit for a while.

If it still drops, it's bad piston seals. If not, then it's something related to the 3 pt valve, a little bit more complex.

 

[oosik]

Or the gaskets on the locking knob may be allowing fluid to leak past.

I think ptsg has the way to find an answer.

 

[The Gaul]

There is a knob under the seat, that adjusts the speed the 3 pt drops, or if fully closed, locks the 3 pt in place. Still lets it raise at any speed though.

Do this simple test to rule out bad piston cylinders on the 3 pt hitch cylinder. Raise the 3pt to max height, turn the knob so it locks the 3 pt in place, move the 3 pt lever to the lower position, shut down the tractor and let it sit for a while.

If it still drops, it's bad piston seals. If not, then it's something related to the 3 pt valve, a little bit more complex.

Thank you, I will try.
Just for perspective, whatever that knob's position was in during my initial year of ownership (even at 'fast drop') did not trigger the current symptoms.

 

[rScotty]

There is a knob under the seat, that adjusts the speed the 3 pt drops, or if fully closed, locks the 3 pt in place. Still lets it raise at any speed though.

Do this simple test to rule out bad piston cylinders on the 3 pt hitch cylinder. Raise the 3pt to max height, turn the knob so it locks the 3 pt in place, move the 3 pt lever to the lower position, shut down the tractor and let it sit for a while.

If it still drops, it's bad piston seals. If not, then it's something related to the 3 pt valve, a little bit more complex.

The OP has already done that test and it doesn't drop.
It could be the 3pt valve, but having an implement drop that much seems rare.

He says it started dropping when he added the F&R extra hydraulic systems.
My bet is that the leakage is internal leakage in one of the accessory hydraulic systems - probably in a rear hydraulic Control Valve if the rear system has one or more. Control valves are sealed internally against leakage simply by the quality of their machined fit in the valve bore. There are no internal O rings. So they all leak a little bit internally and more over time. More expensive control valves leak less and have finer control. It's just the cost of precision machining.

It could also be the grapple's control valve. But those are usually a solenoid operated flow/noflow type which doesn't leak as easily internally.

To get started, I'd remove pressure from the rear hydraulic setup. Make sure not to accidently deadhead that pressure line. Take it to the sump or Y to a return line if not sure. Then see if the 3pt problem is still there.
rScotty

 

[The Gaul]

There is a knob under the seat, that adjusts the speed the 3 pt drops, or if fully closed, locks the 3 pt in place. Still lets it raise at any speed though.

Do this simple test to rule out bad piston cylinders on the 3 pt hitch cylinder. Raise the 3pt to max height, turn the knob so it locks the 3 pt in place, move the 3 pt lever to the lower position, shut down the tractor and let it sit for a while.

If it still drops, it's bad piston seals. If not, then it's something related to the 3 pt valve, a little bit more complex.

I performed this test, and it stayed in place for 2 hours. Didn't even drop an inch....

 

[The Gaul]

The OP has already done that test and it doesn't drop.
It could be the 3pt valve, but having an implement drop that much seems rare.

He says it started dropping when he added the F&R extra hydraulic systems.
My bet is that the leakage is internal leakage in one of the accessory hydraulic systems - probably in a rear hydraulic Control Valve if the rear system has one or more. Control valves are sealed internally against leakage simply by the quality of their machined fit in the valve bore. There are no internal O rings. So they all leak a little bit internally and more over time. More expensive control valves leak less and have finer control. It's just the cost of precision machining.

It could also be the grapple's control valve. But those are usually a solenoid operated flow/noflow type which doesn't leak as easily internally.

To get started, I'd remove pressure from the rear hydraulic setup. Make sure not to accidently deadhead that pressure line. Take it to the sump or Y to a return line if not sure. Then see if the 3pt problem is still there.
rScotty

Thank you, great info.
The locking knob as referred to in my first message was the one underneath the lever:

What ptsg (and you) seem to refer to is this one :

As stated in my prior message, I just performed the test by closing the knob under the seat and the attachment held in place for 2 hours (no drop whatsoever).

 

[ptsg]

Thank you, great info.
The locking knob as referred to in my first message was the one underneath the lever:
View attachment 1712227

What ptsg (and you) seem to refer to is this one :
View attachment 1712226

As stated in my prior message, I just performed the test by closing the knob under the seat and the attachment held in place for 2 hours (no drop whatsoever).

That is what I understood and why I suggested the that knob under the seat. Thanks for the pictures and for clarifying that info.

Now we ruled out any bad seals on the piston. I think we can revert back to the new valve installation. Is this the OEM valve? Or an aftermarket one?

I don't have a service manual for the NS series where we could check the hydraulic diagram.

 

[part-time-Farmer-NC]

My kioti often drops slowly when I trav erse down the rod, and it's bumpy. Since the first time when I am driving any distance I always lift up on the draft control lever. That has always stopped it for me. ??

 

[The Gaul]

That is what I understood and why I suggested the that knob under the seat. Thanks for the pictures and for clarifying that info.

Now we ruled out any bad seals on the piston. I think we can revert back to the new valve installation. Is this the OEM valve? Or an aftermarket one?

I don't have a service manual for the NS series where we could check the hydraulic diagram.

I bought the OEM kit from Kioti which basically allows to install an extra double acting valve assembly. My tractor came with one set of valves in the back. The installation involved taking off the valve cover from the OEM valve assembly, install longer bolts, and add a second double acting assembly (#1 in the schematic below) next to it. It is positioned just under the driver's seat, to the right. I attached the installation instructions that came with the manual as a pdf file. Slide 1 provides a quick overview of the system. Here's a screenshot, further details attached :