Top Link attach hole

3RRL · Jan 9, 2006

( This is what happened when they delivered my brush hog. The top link was longer than the lift arms because they didn't mount the bottom pins on the brush hog to their lowest position. The lift would only move the front of the brush hog up about 1", whitch is all that was allowed in taking up the slack in the movable top link position on the brush hog.

Moving the lift pins down on the brush hog fixed the problem.)

I guess I didn't get this part? Not sure what you mean here.

CT_Tree_Guy · Jan 10, 2006

Rob, I think I get it, but I'm old, so I can never be too sure. It just seems that if the top link is "too long", it has no "choice" but to "push down" on the attachment as the lift arms rise, thereby tilting the rear of the attachment down. Lowering the pin placement on the attachment effectively "shortens" the top link??? Brain ... hurts .... must ... stop .... thinking ...... John out

3RRL · Jan 10, 2006

John,
I guess I should've been more clear on my question above. I get the principle but I couldn't figure why his tractor has a top link longer than his lift arms? It should be adjustable enough to become shorter than the lift arms? Mine is...
The other part was repositioning the the lower lift pins on the brushhog, because mine only has one spot for the lower link pins on it.
Just confused ...it's tough to be an idiot, ya know?

CT_Tree_Guy · Jan 10, 2006

Just confused ...it's tough to be an idiot, ya know? 

Actually, I kind of enjoy it! /forums/images/graemlins/smile.gif

3RRL · Jan 10, 2006

What...?? Did I read that right...???
You enjoy Me being an idiot...??? /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gifHA!
Well, you're not the only one. /forums/images/graemlins/grin.gif

Bob_Young · Jan 10, 2006

/forums/images/graemlins/grin.gif It's all relative. I enjoy being an idiot when I think of how much us idiots upset the really intelligent people. We've definitely got 'em outnumbered. /forums/images/graemlins/grin.gif

Anyway, I'm learning alot on this thread. Keep those thoughts coming.

3RRL, many of your thoughts echo my own with one exception. If the toplink were level and the implement, in normal operation, encountered a major obstruction; the toplink would be in compression as the implement tried to pivot forward around the lower lift arm attach points. This would place a forward acting (pushing) force at the tractor attach point while the lower lift arm attach points would be subject to rearward acting (pulling) forces. The implement might not pivot away from the obstacle.

If the toplink were angled up toward the implement the implement could rotate around the top link attach point and tend to lift itself over the obstacle. In so doing the lower lift arms would raise freely to help with this.

If the toplink were angled down toward the implement, I think it would be much like the level toplink case except the implement would definitely not pivot. The hitch mechanism would bind because the lower arms would resist being pushed down.

This talk about pivoting implements over obstructions might not be reality, however. I can remember hooking a 2 bottom moldboard plow on a big tree root once and the only pivoting was when the front of the Ford 4000 pivoted skyward. Come to think of it, the toplink may have been angled down toward the plow on the Ford.

But, as engineers often do, we may be overthinking this. Pick a hole that works and go with it has its appeal. That's pretty much how its' done with Ag tractors. But Ag tractors have beefy behinds compared to CUTs. The rear axle casting of my L4300 looks delicate compared with the Ford 4000.

Thanks to all for the insights.
Bob

Soundguy · Jan 10, 2006

I can tell you how this relates to a ford, with multiple holes in it's toplink rocker. The lowest hole is used for heavy implements, whether ground engaging or not... but specifically ONLY the lower hole for high draft implements.. like blows / box blades / rigid shank cultivators. The upper holes are used for very light draft implements, like spring tooth harrows, as these implements don't have enough draft to activate the draft sensing hyds.. the toplink rocker is a lever.. the higher up you go.. the more mechanical advantage.. thus more stress on the toplink rocker/pump sensing components. The ford manual is very specific about not putting high draft loads int he holes with more mechanical advantage.. as it can damage the valving and linkage that operates the draft control.. etc.

soundguy

RalphVa · Jan 10, 2006

On my LX4, it was not possible to adjust the top link to be shorter than the lift arms at the mowing height (about 3") that I wanted. When the lift pins were moved to their lower positions on the LX4, this kicked the top link attachment point forward, thus shortening the top link length needed.

Ralph

Gavman · Jan 11, 2006

3RRL

Sorry to change the subject, but how does your top and tilt work with your Pat's Easy change. I am wondering if it will bend any of the parts when I angle my box blade as far as it will angle? /forums/images/graemlins/confused.gif

3RRL · Jan 11, 2006

Hi Bob,
Just wanted to make a couple of points about my first post on the thread...
( 3RRL, many of your thoughts echo my own with one exception. If the toplink were level and the implement, in normal operation, encountered a major obstruction; the toplink would be in compression as the implement tried to pivot forward around the lower lift arm attach points. This would place a forward acting (pushing) force at the tractor attach point while the lower lift arm attach points would be subject to rearward acting (pulling) forces. The implement might not pivot away from the obstacle.)
Yes I agree with that principle as I tried in my feeble explanation. /forums/images/graemlins/grin.gif

( If the toplink were angled up toward the implement the implement could rotate around the top link attach point and tend to lift itself over the obstacle. In so doing the lower lift arms would raise freely to help with this.

If the toplink were angled down toward the implement, I think it would be much like the level toplink case except the implement would definitely not pivot. The hitch mechanism would bind because the lower arms would resist being pushed down.)
Well, at this point I would say the top link is a rigid brace and regardless of it's angle, it would not allow the implement to pivot, as you mentioned about the tractor front raising up.
( I can remember hooking a 2 bottom moldboard plow on a big tree root once and the only pivoting was when the front of the Ford 4000 pivoted skyward. Come to think of it, the toplink may have been angled down toward the plow on the Ford.)

In my first response I wanted to point out that on a boxblade the force to the blade causes a rearward pulling of the implement thereby making it WANT to pivot around the lower link pins, not that it actually does. The only way to really make the implement pivot on the lower link pins is to have swivel brackets such as used on a brushhog to keep the implement wheel in contact with the ground. Without the swivel bracket the brushhog moves up in the air when the tractor front dips down into a ditch or something.

In fact, a rigid top link will keep it from pivoting around the lower link pins. The implement raises up when it hits an obstacle because the lower link arms raise up....that is if it skips over and does not "dig into" it. I was referring to the stress the casting/tractor sees, that is reduced because of the angle of the top link (vector force) instead of a direct force, with the top link dead square to the casting.

As you said, we're probably making more of this than necessary, but when you opened the thread it really got me thinking about the forces and such, not so much what the manual says to do. ( Pick a hole that works and go with it has its appeal. That's pretty much how its' done with Ag tractors.)
That's pretty much how I feel about it too, although my manual also states to use the heavier ground engaging implements on the lower holes.