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.