Help Diagnosing No Hitch Operation Under Load

[KrisD_in_WV]

Greetings!

I am relatively new to hydraulics and have read through many of the extensive, informative posts in this forum. I have attempted to diagnose my problem with the resources I have available but have come to a stand still. I am trying to determine the highest probability of where the fault is in my hydraulic system. I will attempt to be as thorough as I can be, but am sure that there may be more questions.

Problem
Hitch will not raise under load exceeding the weight of a man.

Facts
Category II TPH rated at 3400 pounds of lift

- Hitch raises and lowers with no load perfectly although it does so slowly in each direction

- Hitch cannot raise a 1000 pound implement

- Hitch will raise with me standing on the bars (198 pounds)

- When I put the hitch control in the "raise" position, I can manually raise the implement and it stays; no leak down when I manually put it into position with 1000 pound load

- Some fine metal particles were present in the old fluid

What I have Done So Far
- Flushed hydraulic fluid and changed filter (original fluid was mostly clear however toward the end of the draining, moisture was noticed in about the last gallon)

- Removed a sampling of hoses and checked for obstructions; none found

- Verified flow through bypass plumbing

- Visually inspected entire circuit; found some fluid in various places but cannot tell if it from what I spilled or if there are leaks. Fluid amount was negligible.

Question
- Based on what I have shared, is the probability higher that my lift cylinder is bad or that I have a pump that is performing sub-optimally?

Thanks in advance for the help.

~kd

 

[AKKAMAAN]

Greetings!

I am relatively new to hydraulics and have read through many of the extensive, informative posts in this forum. I have attempted to diagnose my problem with the resources I have available but have come to a stand still. I am trying to determine the highest probability of where the fault is in my hydraulic system. I will attempt to be as thorough as I can be, but am sure that there may be more questions.

Problem
Hitch will not raise under load exceeding the weight of a man.

Facts
Category II TPH rated at 3400 pounds of lift

- Hitch raises and lowers with no load perfectly although it does so slowly in each direction

- Hitch cannot raise a 1000 pound implement

- Hitch will raise with me standing on the bars (198 pounds)

- When I put the hitch control in the "raise" position, I can manually raise the implement and it stays; no leak down when I manually put it into position with 1000 pound load

- Some fine metal particles were present in the old fluid

What I have Done So Far
- Flushed hydraulic fluid and changed filter (original fluid was mostly clear however toward the end of the draining, moisture was noticed in about the last gallon)

- Removed a sampling of hoses and checked for obstructions; none found

- Verified flow through bypass plumbing

- Visually inspected entire circuit; found some fluid in various places but cannot tell if it from what I spilled or if there are leaks. Fluid amount was negligible.

Question
- Based on what I have shared, is the probability higher that my lift cylinder is bad or that I have a pump that is performing sub-optimally?

Thanks in advance for the help.

~kd

What type of hydraulic system/equipment is it, open center or closed center system?
Does the hitch lift with normal speed? or is it with slower than normal speed?
Can you make hitch lift more weight (increase supply pressure) if you increase pump flow (rpm)?
Can you attach a pressure gauge to check main Pressure Relief Valve , PRV, setting?


Without these answers there is just guesses, like....
<Control valve not directing the entire pump flow
<PRV stuck open
<hitch cylinder seal leaking bad
<pump worned out (you did find metal in old fluid)

 

[KrisD_in_WV]

What type of hydraulic system/equipment is it, open center or closed center system?
Does the hitch lift with normal speed? or is it with slower than normal speed?
Can you make hitch lift more weight (increase supply pressure) if you increase pump flow (rpm)?
Can you attach a pressure gauge to check main Pressure Relief Valve , PRV, setting?


Without these answers there is just guesses, like....
<Control valve not directing the entire pump flow
<PRV stuck open
<hitch cylinder seal leaking bad
<pump worned out (you did find metal in old fluid)

Thanks for the reply. The system is Open Center. The hitch speed with no load is quite slow compared to others I've seen. For example, under no load, at full engine RPM, it takes almost 5 seconds to raise to the transport position. When I raise engine RPMs while lifting with no load, it does increase the raise speed of the hitch but only very slightly. I have to obtain a gauge to check pressure. I do not have one here and will have to drive quite far to obtain one.

Thx!

 

[mmurphy]

Another thing that might be important is what kind of tractor you have.

 

[KrisD_in_WV]

Another thing that might be important is what kind of tractor you have.

It is a Belarus 532.

 

[patrick_g]

It is a Belarus 532.

Ahh, a big chunk of Russian cast iron... The good news with those is that they are low tech and not a lot of sophistication to deal with when making repairs. The bad news is that they typically need a lot of repairs.

At least your 3PH raises and lowers. My Kubota 3PH is totally dead. I hit a ditch hidden by snow with the brush hog up in the air and the shock made the 3PH drop the implement to the ground where it still sits awaiting tractor repairs which I will start this week as the grass is greening and I am not needing the tractor for hauling round bales to the herd every other day. I suspect (strongly hope) the seals were blown out and no metal parts are damaged.

Pat

 

[KrisD_in_WV]

Ahh, a big chunk of Russian cast iron... The good news with those is that they are low tech and not a lot of sophistication to deal with when making repairs. The bad news is that they typically need a lot of repairs.

At least your 3PH raises and lowers. My Kubota 3PH is totally dead. I hit a ditch hidden by snow with the brush hog up in the air and the shock made the 3PH drop the implement to the ground where it still sits awaiting tractor repairs which I will start this week as the grass is greening and I am not needing the tractor for hauling round bales to the herd every other day. I suspect (strongly hope) the seals were blown out and no metal parts are damaged.

Pat

Surprisingly, I haven't had to do much to this one and based on the preservation of the paint nearly everywhere, it doesn't look like much as been serviced or replaced. As you said though, it's very low-tech and everything that may need to be worked on is very accessible.

I'm wondering if I can take off the outer cover of the pump and inspect the mechanism to see if there is evidence of the pump being fouled. Ultimately, I know a pressure gauge would serve me best, however I'm trying to see what else I can do diagnostically before making the long drive to obtain one.

 

[mmurphy]

Do you run anything else from hydraulics that could be used to compare of what it was like before?

 

[KrisD_in_WV]

Do you run anything else from hydraulics that could be used to compare of what it was like before?

Unfortunately not, and the original owners have passed away.

 

[mmurphy]

Pressure check is about the only thing to do then to start diagnosing the problem. Like AKKAMAAN says it is all guess work as of now.