Hyd. Toplink chattering?

Bob_Young · Jun 11, 2006

I've had the CCM hydraulic toplink on my L4300 several months now and think it's great. Just started using it with my new Woods 65" Boxblade and noticed a problem.

When I go to extend the toplink while holding the BB off the ground with the 3pt. hitch, I hear a deep vibrating groan that can be felt as well as heard. This doesn't occur if I extend the link while the BB is on the ground or while retracting the link, BB on the ground or not.

I figure the weight of the BB is causing the cylinder to try to overrun the hydraulics and the checkvalve is rapidly opening and closing to prevent this....and that the checkvalve action is the cause of the groan. If I've got this right, there's not much that can be done about it; but I'm wondering if someone else has a better answer. I did a search but didn't find anything...may not have used the right terms.

So, has anyone else experienced this? If so, Are there any solutions other than simply lowering the implement to the ground before extending the link?
Thanks.
Bob

Bob_Young · Jun 11, 2006

I've had the CCM hydraulic toplink on my L4300 several months now and think it's great. Just started using it with my new Woods 65" Boxblade and noticed a problem.

When I go to extend the toplink while holding the BB off the ground with the 3pt. hitch, I hear a deep vibrating groan that can be felt as well as heard. This doesn't occur if I extend the link while the BB is on the ground or while retracting the link, BB on the ground or not.

I figure the weight of the BB is causing the cylinder to try to overrun the hydraulics and the checkvalve is rapidly opening and closing to prevent this....and that the checkvalve action is the cause of the groan. If I've got this right, there's not much that can be done about it; but I'm wondering if someone else has a better answer. I did a search but didn't find anything...may not have used the right terms.

So, has anyone else experienced this? If so, Are there any solutions other than simply lowering the implement to the ground before extending the link?
Thanks.
Bob

MadReferee · Jun 11, 2006

( I figure the weight of the BB is causing the cylinder to try to overrun the hydraulics and the check valve is rapidly opening and closing to prevent this....and that the checkvalve action is the cause of the groan. )

Not quite sure what you mean by this. A pilot operated check valve will not open unitl the pilot (cracking) pressure has been reached, usually 500 psi on those CCM check valves. Since the cylinder works correctly when the BB is grounded I don't think the cylinder or the check valve is the culprit.

I have seen cylinders struggle to move very lightweight objects and the problem turned out to be geometry related whereby the cylinder was trying to push a pinned implement and all the cylinder did was push against the pin instead of causing the pin to rotate.

I have a CCM hydraulic top link and have used it with a BB and a snowblower, which are heavy implements, and never experienced what you are.

greg_g · Jun 11, 2006

Move the tractor end of the HTL to the other set of holes in the toplink bracket. See if that changes anything.

//greg//

3RRL · Jun 11, 2006

Mine has done the same only if the implement is lifted up high by the 3pt. Does not do it under normal operation, and I use it a lot. I just figured it was straining when the geometry changed with the boxblade lifted high for transport. I normally dont even adjust the hydraulic top link in that position, but noticed it after hooking it up and trying everything out. I'll have to give a try what Greg mentioned to see it it makes a difference.

Bob_Young · Jun 11, 2006

Thanks for the idea, greg. I'll give that a try.

3RRL: I get the GROAN whether the BB is lifted high or just barely being supported by the hitch (part of BB weight supported by the ground). The only time it doesn't groan on extension is when the full weight of the BB is on the ground.

Don't think it's struggling to do anything Mad, but there could be a geometry issue. The weight of the BB would naturally pull the toplink to full extension were there no valving in the hydraulic circuit to prevent it. When the weight of the BB is fully on the ground, the toplink extends and tilts the BB easily and quietly. With weight on the lower links, something could be binding that doesn't when the hitch is floating.

I used the toplink over the winter with a rear blade for moving snow. Never had this happen on that implement. But then I always had the blade's skid shoes on the ground and used the link to set some clearance between the blade edge and the pavement.

Well now you guys got me thinking. I might try some different settings on the telescopic stabilizers as well. I set 'em for no sway at hookup ; they might be binding when the hitch is supporting weight.

Got Pat's EZ hitch on the ends of the lower links. Those things don't rotate to align with the pins like the ball ends do. Might need to adjust yaw and roll on those....the racket could be coming from the pins. If that were the case, you'd think it'd groan on cylinder retraction as well.

Just knowing that this isn't common is a great motivator.
Thanks.
Bob

DiskDoctr · Jun 11, 2006

Bob,

My CCM toplink does the same thing.

Sounds like you're moving something that has been sitting a hundred years and creaks...

Once it is warmed up and used it seems less, but even lowering it is sometimes a little jerky.

I think it is due to the geometry, where at many multiple points the cylinder is rapidly pushing, then holding back as the BB rotates under minimal strain (slight binding due to geometry). It pushes when the BB binds, then holds when the BB is falling.

I think it may also be made worse by the low flow volume of my included rear remotes on my Mahindra 3510. This is made even worse in that I am usually adjusting when at low idle, between operations, in turns, etc.

If you learn anything else, let us know.

-JC

have_blue · Jun 12, 2006

It may not be top link per se.

I had the same problem on a Bush Hog box blade. It was a good heavy unit, but when pushing it chattered horribly at times. Adjusting the angle helped, but that hurt productivity.

On close examination, the steel straps for the top link needed gusseting or should have been made from heavy "L" shaped or box shaped members instead of straps. When pulling it was fine, but when pushing the straps bowed just a little bit. It was a borrowed implement, but if it were mine, I would have welded some big steel to it. /forums/images/graemlins/tongue.gif

greg_g · Jun 12, 2006

( the straps bowed just a little bit. It was a borrowed implement, but if it were mine, I would have welded some big steel to it. )

The straps are supposed to bend. If there wasn't some built-in flex, cutting heights would be erratic - and something would (will) end up breaking. Sooner more likely than later.

//greg//

JerryG · Jun 12, 2006

See attachment. Are these the straps that you are talking about or have I missed something?

4x4sche · Jun 12, 2006

Mine does the same. It is the check valves. If you move it more quickly it won't do this, you can't feather pilot operated valves when there is a lot of load (weight) on the cylinder.

John

N80 · Jun 13, 2006

Jerry, I think he is talking about a Bush Hog brand box blade. But I'm not sure which straps he's referring to either. I have the SBX 720. The mast posts are pretty wide and triangle shaped. They might be stronger if they were gussetted but I don't think these flex. They might, but I haven't seen it. There is a T-shaped 'strap' that comes down from the top of the mast to the back edge of the blade. There are two L-shaped straps at the base of the mast that come back from the front edge of the box to the rear.

3RRL · Jun 13, 2006

N80,
( They might be stronger if they were gussetted but I don't think these flex. They might, but I haven't seen it.)
Yeah, I know mine dont flex at all. This Howse is completely rigid in it's fabrication.

greg_g · Jun 13, 2006

My mistake. He was talking boxblade, I was thinking rotary cutter. My BB is rigid as well - just like your photos show. My rotary cutter on the other hand, has long steel straps that flex to compensate for the changing geometry between the toplink and the lift arms.

//greg//

N80 · Jun 13, 2006

Wow, I've never seen a BB with hydraulic ripper adjustment. That's almost decadent. /forums/images/graemlins/grin.gif

Is that a full TNT or just a hydraulic top link?

Back to the OP, have you tried changing the top link attachment point on the tractor to see if changing the geometry eliminates the chattering?

Bob_Young · Jun 13, 2006

Not yet, George; been off the tractor for a couple of days. Might get a chance tomorrow evening. I'll report the results.
Bob

3RRL · Jun 13, 2006

Not sure that it matters much, but I was taught to use the lower attachment hole on the tractor for ground engaging inplements. I have no quams about trying another location like Greg mentioned (the middle or top hole for me) . As I said above, the groan doesn't concern me enough but I'd like to try the other holes just to eliminate the groan.

N80,
( Is that a full TNT or just a hydraulic top link?)
I wish...No it's only the top link. I really want to get the tilt cylinder(s) but I've been told they are back ordered to forever?? I thought about buying my own but I want the check valves on the cylinder.

Bob_Young · Jun 21, 2006

Follow up on the chattering toplink:

Today I moved the hyd. toplink down to the middle set of holes from the top set. I also put the left side 3pt. hitch stabilizer in a 'float' setting to eliminate any chance of binding. After these changes, I still got the 'Groan' noise when the toplink was extended with the BB off the ground.

It did seem, however, that the noise was slightly less and I noticed that if the toplink was extended very slowly, the sound was much 'softer' and not objectionable. On the other hand, extending the link rapidly was almost like blowing a horn. Improvement, if there was any, was small. With BB on the ground, extension & retraction were completely silent as before.

Was going to try the link in the bottom set of holes, but found that the PTO guard interfered with it and so left it in the middle set. Took a look at the Pat's EZ change and couldn't see where there was any binding....the hook's are fairly well aligned with the pins. Might hit 'em with some LPS3 though.

Looks like it's something I'll have to live with. Anyone know whether this will damage the cylinder over time?
Bob

greg_g · Jun 21, 2006

Bob_Young said:
Today I moved the hyd. toplink down to the middle set of holes from the top set. I also put the left side 3pt. hitch stabilizer in a 'float' setting to eliminate any chance of binding. After these changes, I still got the 'Groan' noise when the toplink was extended with the BB off the ground.

I assumed - maybe incorrectly - that the outside lever was draft control, the inside lever position control. If that's the case with your tractor, bottoming the inside lever means you're raising/lowering the TPH with the draft control lever. Don't know if that's contributing to the "groan", but it might not hurt to verify which lever is which.

Also, I thought the word used before was "chatter ", and chatter is reported as not uncommon if heard coming from the pilot/check valve. But when I hear the words hydraulic and cylinder and groan in the same sentence, bent rod comes to mind. Can you extend the cylinder to the max, and put a straight edge on the rod?

//greg//

4x4sche · Jun 22, 2006

The opening pressure of a pilot operated checkvalve depends on the pressure (applied by the load) behind the valve. This is why I said that you can't feather the control when under load without getting a rapid oscillation of the check valve.