5211 hydraulic performance

[sbranson]

Hi all,

I am having a bit of a confounding hydraulic issue with one of my 5211s. Two seasons ago (2017), the 3-pt hitch was drifting down slowly but consistently with a heavy implement attached (2500-3000 lbs). When it reached a certain low point (roughly 4-6" at the end of the lower link arms) it would then raise back up to the original set point and start drifting down again.

At times, if the operator raised the implement too suddenly at high rpms, or the implement was unbalanced to the front (therefore putting more weight into the toplink), this would create a feedback loop in the draft control system. The draft control would trigger, raising the implement and starting it bouncing, which would trigger the the draft control to raise the implement again, etc, etc until the whole implement was bucking violently. This situation could be alleviated by gently lowering the hitch control, lowering the rpm, etc. It was reduced in the M and P settings, and by setting the toplink in a lower hole at the tractor, but not eliminated entirely.

It was also difficult to gently lower implements all the way to the ground. Past a certain point (roughly 2/3rds lowered), the implement would slam down violently.

Last winter I replaced the following with new parts:

Hydraulic lift cylinder
Hydraulic lift piston and rings
Hydraulic distribution valve assembly
O-rings and copper washers

The tractor now holds loads in place as it should, but by the end of the season, it had started to be prone to the draft-control feedback loop of bucking again. It was also back to dropping implements violently once the hitch was lowered past a certain point (again, roughly 2/3rds of the way down).

I am not sure what to try next. Is there something I should be looking for in the draft control system?

I have gotten a ton of great information from this forum over the years. I would be very appreciative if someone can help point me in the right direction.

Let me know if there's any other information I can provide!

Silas

 

[diyfarmer]

If the lift was going down by itself it doesn't matter what major weight you have on it, but at 1300KGs it's fair lot of weight for a little tractor to carry so usually I would said that the lift cylinder under the lift cover needed new seals, but you have it done already. But if it is jumping continually what it's going on is oil is leaking out and feeding back in

 

[sbranson]

Thank you for your response!

When you say "oil is leaking out and feeding back in", are you thinking that it is leaking out from a specific place, or just anywhere in the pressurized part of the system?

I was thinking of replacing the pipe and hollow bolts that connect the distributor assy to the cylinder, and checking/replacing the copper washers again, as the most likely leak points I can think of. Anywhere else you would check on?

If the problem recurs, could it be that we are just wearing out the lift piston seals very rapidly? I bet we have implements in that 2500-3000 lb range on that tractor for 150 hours per season.

Thanks very much!

Silas

 

[diyfarmer]

Your lifting a nice bit of weight for that tractor, the oil could be leaking out of the lift cylinder and then it fills back up again, to test rightly put the lift up to the last and turn off the engine and see how quickly it goes down. Also you could try the pump, if it's worn or leaking. If it's worn at low revs it fails to keep up pressure and with the weight on lift.

 

[sbranson]

I will do this test, and keep the pump in mind as a possible culprit. I will post the outcome once I get around to doing the work.

Thank you!

 

[diyfarmer]

Ya I try to see if there's a leak first then move on to the pump.

 

[sbranson]

Yeah, sounds good. Any advice for finding a leak once the top cover is off? There isn't any way to pressurize the system while it's exposed, is there?

Thank you!

 

[diyfarmer]

Ya I saw the garage where I got one reconditioned before , they used pressurize air to force up the lift

 

[sbranson]

Cool. Thanks!