bouncy 3 point lift arms on L2550.

[Zimcocomp]

What can cause the 3 point hitch to bounce when not down.

 

[North Idaho Wolfman]

Maladjusted three point feed back linkage.

 

[TheOldHokie]

What can cause the 3 point hitch to bounce when not down.

Or a leaky lift cylinder.

Dan

 

[PaulL]

Don't they always bounce? They have upward pressure, not downward pressure. So you can always lift the lift arms by hand - I guess unless it's all the way up, but even then I suspect there's still a bit of play.

 

[North Idaho Wolfman]

Don't they always bounce? They have upward pressure, not downward pressure. So you can always lift the lift arms by hand - I guess unless it's all the way up, but even then I suspect there's still a bit of play.

We do believe he's talking about it bouncing with no input or external movement, it's just doing it on it's own.

 

[Zimcocomp]

Don't they always bounce? They have upward pressure, not downward pressure. So you can always lift the lift arms by hand - I guess unless it's all the way up, but even then I suspect there's still a bit of play.

When lifting a box blade the hunting almost becomes violent.

 

[TheOldHokie]

When lifting a box blade the hunting almost becomes violent.

How long will the 3pt hold a raised implement after you shut off the tractor?

Dan

 

[Vigo]

Ok, so it happens while lifting an actual load. Does it only stutter on the way up and once you stop raising it it stays there normally?

It probably has something to do with position control. I dont know if theres a way to disable that function in order to test that theory. I dont know if its relevant but apparently draft control was optional on that tractor and had a separate lever behind the 3pt lever. Does yours have that?

 

[PaulL]

We do believe he's talking about it bouncing with no input or external movement, it's just doing it on it's own.

Ah. So almost like it's still trying to lift even when it's at desired height? Or is the upper stop not set correctly, so it's still trying to go up when it's already reached the top? Diagnosis would be different between those two. Video would be super useful.

 

[Zimcocomp]

How long will the 3pt hold a raised implement after you shut off the tractor?

Dan

The 3pt hitch drifts down at whatever speed is set on the speed valve under the seat. It raises normally and begins to shake when raising action is stopped. Actually everything works normally when the down speed is closed except it won't go down of course.

 

[Zimcocomp]

We do believe he's talking about it bouncing with no input or external movement, it's just doing it on it's own.

The 3pt hitch drifts down at whatever speed is set on the speed valve under the seat. It raises normally and begins to shake when raising action is stopped. Actually everything works normally when the down speed is closed except it won't go down of course.

 

[TheOldHokie]

The 3pt hitch drifts down at whatever speed is set on the speed valve under the seat. It raises normally and begins to shake when raising action is stopped. Actually everything works normally when the down speed is closed except it won't go down of course.

So thats not drift down. Drift down is when the lift wont hold a raised load. If you raise a load and turn the trsctor off does the raised load remain at the set point or does it slowly drop?

If it drops the bouncing is likely the position control system fighting against the leak down.

If it holds the bouncing at the set point is likely a problem with the position control adjustment.

Dan

 

[North Idaho Wolfman]

The 3pt hitch drifts down at whatever speed is set on the speed valve under the seat. It raises normally and begins to shake when raising action is stopped. Actually everything works normally when the down speed is closed except it won't go down of course.

I'm sticking with Feed back linkage is mal adjusted!

Do you have the WSM (aka service manual) to adjust it?
If not just ask!

 

[Zimcocomp]

I'm sticking with Feed back linkage is mal adjusted!

Do you have the WSM (aka service manual) to adjust it?
If not just ask!

I copied the required page but am having difficulty loosening the the front nut. Is in a bad location. Also noticed the position control only starts raising when the control is near maximum height. Could the feedback arm just fall out of adjustment? It's not been touched since 1986.

 

[TheOldHokie]

I copied the required page but am having difficulty loosening the the front nut. Is in a bad location. Also noticed the position control only starts raising when the control is near maximum height. Could the feedback arm just fall out of adjustment? It's not been touched since 1986.

At top of lift the position control is what stops the lift from trying to go too far. Is posiyion conyrol moving when the lift is at mid point and bouncing?

Dan

 

[Zimcocomp]

At top of lift the position control is what stops the lift from trying to go too far. Is posiyion conyrol moving when the lift is at mid point and bouncing?

Dan

I'll try to check that when I feel a little better. Thanks.

 

[Zimcocomp]

At top of lift the position control is what stops the lift from trying to go too far. Is posiyion conyrol moving when the lift is at mid point and bouncing?

Dan

Yes it bounces along with the hitch . I tried raising the hitch and killing the engine. It does drift down. Not fast but down in a matter of seconds. When I say control is moving I don't mean the handle. I mean the feedback rod.

 

[TheOldHokie]

Yes it bounces along with the hitch . I tried raising the hitch and killing the engine. It does drift down. Not fast but down in a matter of seconds. When I say control is moving I don't mean the handle. I mean the feedback rod.

That sounds like something in the lift circuit is leaking at a prettty good rate. What happens is:

1. You raise the position control lever to the desired height and the lift raises until the control valve goes to neutral when the selected height is reached,
2. With the control valve in neutral the lift is supposed to hold there but because something is leaking the lift starts to drift downward
3. The feedback system sees the drift and opens the control valve to restore the lift to the set point.
4. This drift and restore process simply repeats and repeats as the circuit continues to leak and the feedback system corrects to maintain the set point. The faster the leak the faster the lift oscillates.

Does that match what you are seeing?

Dan

 

[Zimcocomp]

That sounds like something in the lift circuit is leaking at a prettty good rate. What happens is:

1. You raise the position control lever to the desired height and the lift raises until the control valve goes to neutral when the selected height is reached,
2. With the control valve in neutral the lift is supposed to hold there but because something is leaking the lift starts to drift downward
3. The feedback system sees the drift and opens the control valve to restore the lift to the set point.
4. This drift and restore process simply repeats and repeats as the circuit continues to leak and the feedback system corrects to maintain the set point. The faster the leak the faster the lift oscillates.

Does that match what you are seeing?

Dan

Thanks Dan,
I see what you mean. How does the manual control valve under the seat work into that? It holds the load up when closed.

 

[TheOldHokie]

Thanks Dan,
I see what you mean. How does the manual control valve under the seat work into that? It holds the load up when closed.

The lowering speed valve closes off the hydraulic circuit between the lift cylinder and the position control valve.

If the lift holds with the lowering speed valve closed the lift cylinder is not leaking.

That would suggest the leakage is in the position control valve or a component between it and the lowering speed valve.

Dan