3 point hitch drifts down when letting off throttle

[David V]

At times I hook a cattle trailer to my 3 point hitch to move cows from one field to another. When traveling it is in the raised position, then when I get off the throttle to slow down, the 3 point hitch drops causing the trailer to drag the ground. I have tried screwing in the drift speed control in all the way but that hasn稚 helped. Any ideas?

 

[Tx Jim]

Sounds as if 3pt rockshaft piston seal or RS control valve is leaking internally.

 

[David V]

Thanks Jim for the reply...it’s on an LS K 5055, I have know idea what a rock shaft piston is, much less where It’s at. But don’t mind jumping in if it’s not to hard. Any online tutorials?

 

[Tx Jim]

Rockshaft is term utilized in farm equipment to describe a rotating shaft that is used to lift an object such as the shaft that rotates to raise 3 point hitch draft arms. In order for shaft to rotate requires a hyd operated piston with seals to hold hyd pressure. My advice would be to acquire a tech manual for your tractor.

 

[k0ua]

Sounds as if 3pt rockshaft piston seal or RS control valve is leaking internally.

It does sound like and internal leak in the piston seal, but why doesn't the position control try to keep it up? Surely his tractor has position control, and I would think it would oscillate from falling to a quick jerk upward as the position control would attempt to maintain position by opening the valve to let more oil flow toward the piston, which would bleed down quickly and then open the valve again causing the oscillation. This seems puzzling to me.

 

[Tx Jim]

k0ua
My guess is piston seal is leaking faster than hyd pump output is at slow engine speed or more likely it's possible ""trailer tongue load on 3 pt"" is causing 3 pt relief valve to open.

 

[k0ua]

k0ua
My guess is piston seal is leaking faster than hyd pump output is at slow engine speed or more likely it's possible ""trailer tongue load on 3 pt"" is causing 3 pt relief valve to open.

Well, in any case it is "something bad" going on there that needs attention for sure. In technical terms it is "broke".

 

[RNeumann]

I’ve been following this one with interest. Is it likely or possible the cattle trailer with cows overloaded or stressed the 3pt? The tongue weight of the the trailer and cows could be 4000-10000# plus depending on his lash-up.

 

[k0ua]

I’ve been following this one with interest. Is it likely or possible the cattle trailer with cows overloaded or stressed the 3pt? The tongue weight of the the trailer and cows could be 4000-10000# plus depending on his lash-up.

I was wondering that too. I meant to ask what he thought the tongue weight might be.

 

[ptsg]

Tractors usually have a safety relief valve on the 3 pt, set at a much higher pressure from the system pressure, to prevent damage from overloading, bouncing on the road and so on. It will just let go down, till the pressure reduces.

 

[searcyfarms]

has it always acted this way since you started doing it, or did it start dropping recently/all of a sudden, my point is, you might be overusing it and broke it or it has just failed VS what you are doing is more than your tractor can handle/was designed for

 

[RNeumann]

Tractors usually have a safety relief valve on the 3 pt, set at a much higher pressure from the system pressure, to prevent damage from overloading, bouncing on the road and so on. It will just let go down, till the pressure reduces.

Fist words in OP’s post is “At Times”. I’m wondering if all that is happening is the 3pt is relieving as you describe?
I’m no expert on this- just wondering.....

 

[ptsg]

Fist words in OP’s post is “At Times”. I’m wondering if all that is happening is the 3pt is relieving as you describe?
I’m no expert on this- just wondering.....

It might be. You did mentioned that a cattle trailer can have lots of tongue weight. I'm not familiar with this though but might have some logic behind it. If the tractor goes over a bump or something, it might create enough load on the 3pt to open the safety valve.

I'll give you the example of my tractor, because that's the one I have the specs for. The system pressure is set at 2600 PSI, while the 3 pt safety relief valve is set at around 3050 PSI.

I don't know the lift capacity for the OP's tractor but it might possible that the safety valve is kicking in to protect the 3 pt. If it's near the safety valve limit and with higher engine RPM, it can more or less compensate for the drop rate.

We don't have any details like tractor hours, age, does this happen when loaded or unloaded? And so on. Till then, we can't really have any certain on the problem.

 

[BukitCase]

Lift capacity for BOTH the OP's tractors is 4079 lbs
TractorData.com LS XU555 tractor information
XU Series | LS Tractor

If tongue weight's the problem, I probably wouldn't wanna tow that trailer with my Corolla :laughing: ...Steve

 

[3Lfarms]

I’m curious how heavy that trailer is. I have the same tractor as OP. My ditch and bank mower weighs over 2100 lbs and it will hang on the three point overnight without dropping more than an inch or two.

 

[Sawyer Rob]

It could also be the hydraulic pump is getting weak too...

SR

 

[Tx Jim]

It could also be the hydraulic pump is getting weak too...SR

If pump raises 3 pt with load attached BUT then load leaks down without 3 pt control lever moving then I'm confident the hyd pump isn't weak or the problem

 

[searcyfarms]

if he is moving cattle and two cows are standing in the front of the trailer thus loading the tongue, granted the axles are taking some of the weight but it wouldnt take very long at all to get some serious weight on that tongue not to mention the weight of the trailer to begin with, then go over a bump and the pressure that adds could be more than substantial enough to cause a bypass in the hydraulic system and damage a valve and then cause low pressure issues at idle

 

[Sawyer Rob]

If pump raises 3 pt with load attached BUT then load leaks down without 3 pt control lever moving then I'm confident the hyd pump isn't weak or the problem

Depends, if he has to keep the engine reved up pretty good to lift/hold the load, it could be the pump is getting weak... (leaking internally)

I've seen that happen before...

SR

 

[Tx Jim]

Depends, if he has to keep the engine reved up pretty good to lift/hold the load, it could be the pump is getting weak... (leaking internally)

I've seen that happen before...

SR

As I previously stated once load is raised to desired position then 3 pt control valve closes if 3 pt valve,piston seals or thermal relief valve aren't leaking hyd pump is no longer in the picture IE isn't required. If 3 pt load exceeds tractors rating then thermal relief valve will open allowing 3 pt ot lower.If pump is needed to maintain 3 pt height the ""3 pt valves or piston seals in question are LEAKING"" allowing 3 pt to settle. Many hyd pumps have been replaced only to determine that the replaced pump was not at fault. I've had 13 yrs experience serving as a dealer service manager solving many.many hyd problems.