Annoying 3 pt lift cycling

[Fireemt538]

Hey all, anyone else ever encountered this?? Recently my 3 pt has started "cycling". When you raise the 3 pt with anything hooked up to it, regardless if its raised just above the ground or all the way up, it raises to where you have the 3 pt lever set and then drops about 2-3 inches then raises back up, drops, up, drops, up over and over again.... VERY annoying..... However it will hold position if I lock the 3 pt in position via the knob under the seat. The heavier the implement the faster it cycles, lighter the slower respectivley. I have a gauge hooked inline and you can watch the pressure go from 0 to 2200psi every time it cycles. This can't be good for the ol' pump at all.

This is on a B1750 with position control

 

[mmurphy]

I would imagine it to be different from type of tractor. What do you have?

 

[J_J]

One other fellow on here had a similar problem, and he determined it was a sticking relief valve in the 3pt assembly.

 

[MarkV]

You check to make sure your hydraulic fluids are topped off?

MarkV

 

[DaveOmak]

It may be, you have the 3 pt in the "traction control" position when it is cycling. "Depth control" when it does not cycle.
The knob under the seat selects these 2 positions. It is my understanding, the "traction control" adjusts the height of the implement to prevent excessive tire spin when plowing etc.
The top link bracket under the seat should have 2 or 3 holes to attach the top link to it. The top hole has more leverage and makes the "traction control" more sensitive to pulling load and is used with "easier pulling" implements.
The bottom hole would be used for "harder pulling" implements such as a bottom plow.
"Depth control" is used when you want a constant depth of the implement as in sub-soiling or installing irrigation or using your back blade.
Your manual should explain the various functions of the hydraulics in the "depth-traction" modes.
Dave

 

[MarkV]

The Kubota B1750 is a small tractor and not many of them have draft control. Can't say as I have ever heard of traction control, at least not on a small tractor.

MarkV

 

[DavesTractor]

Hey all, anyone else ever encountered this?? Recently my 3 pt has started "cycling". When you raise the 3 pt with anything hooked up to it, regardless if its raised just above the ground or all the way up, it raises to where you have the 3 pt lever set and then drops about 2-3 inches then raises back up, drops, up, drops, up over and over again.... VERY annoying..... However it will hold position if I lock the 3 pt in position via the knob under the seat. The heavier the implement the faster it cycles, lighter the slower respectivley. I have a gauge hooked inline and you can watch the pressure go from 0 to 2200psi every time it cycles. This can't be good for the ol' pump at all.

This is on a B1750 with position control

You have fluid leaking past the seals on the piston that raises and lowers the three-point. It sags a little and the position control takes notice and decides to get it back into proper position. It is generally not too difficult to replace the rings/seals on that piston and I think that will solve the problem.

 

[rgtractor]

I had the same problem and ended up replacing a lift arm cylinder.

 

[Fireemt538]

The sticky relief valve was something I was wondering about but it didn't seem like it could be the culprit since I never actually hear it "relieving", but then again, I only have the homeowner type of knowledge about hydraulics.

As far as draft and traction control.... don't believe it applies to this tractor, as it only has position control and the function of the knob under the seat is only for controlling how fast the implement drops when you lower the 3 pt lever... at least that is my understanding from the manual ect.... thats all it seems to affect when I adjust it

Yes the hydraulic oil level is full, checked it several times just to be sure over the last couple weeks...

The leaking seals would make sense after I think about it. So I think I'm down to basically two possibilities: relief valve as J_J suggested or leaking seals on the piston like Dave suggested. Any way to do any type of trouble shooting to better pinpoint the problem between the two? or is it one of those just tear it down and experiment things? Is it hard to do? and I assume the relief valve would be in the 3 pt valve assbly?

 

[jinman]

Lift an implement all the way to the top with the 3PH set normally (drop speed control valve open). Now, shut off the engine and watch for the 3PH to drop. If it drops, it's the lift cylinder. If it does not drop, it might be a position control out of adjustment, but my money is on the lift cylinder seal.