Three point linkage

Rooster1262 · Jun 29, 2013

Hey guys, I have just bought an older style fiat 500 tractor. I am having difficulties working out the mechanism where the top link connects to tractor. In particular where the pin locks to top link.

I have worked out arms need to be in up position to engage a lever which when arms lower the back plate I assume will come out to insert pin.

It is at this point is where I have been stumped. The back plate doesn't move at all therefore pin is unable to be inserted to lock in top link.

Now I know that my description probably a little vague, however I can email pics to give a better visual.

Your assistance Would be really appreciated.

Rooster.

rrlund · Jun 30, 2013

Is this kinda like what you're talking about? On this one,if the pin is the right diameter and length it slides in OK.

Pycoed · Jun 30, 2013

(quoted from post at 06:07:53 06/30/13) Hey guys, I have just bought an older style fiat 500 tractor. I am having difficulties working out the mechanism where the top link connects to tractor. In particular where the pin locks to top link.

I have worked out arms need to be in up position to engage a lever which when arms lower the back plate I assume will come out to insert pin.

It is at this point is where I have been stumped. The back plate doesn't move at all therefore pin is unable to be inserted to lock in top link.

Now I know that my description probably a little vague, however I can email pics to give a better visual.

Your assistance Would be really appreciated.

Rooster.

If it's the same as my UTB 445 (which is a Fiat 450 I believe) then you probably need to grind off the head of the top link pin at 30-45 degrees to be able to insert it. The "back plate", by which I assume you mean the mounting for the top link, is a hinged plate restrained by a large bent leaf spring on the left side. It is this leaf spring that prevents pushing a conventional pin into the top link mounting holes (there are 4 alternative sets of holes on mine). The reason for the hinged mount is to provide feedback for the draft control mechanism (Google Harry ferguson & draft control for a description & explanation).
Just grind the heel end of the standard toplink pin just enough so it can be inserted _ I think I knocked about 1/4" off mine.

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paul · Jun 30, 2013

Can't you just put the pin in from the right instead if from the left?

Paul

rrlund · Jun 30, 2013

No. Those bolt heads stick out too far.

vapet · Jun 30, 2013

Have found the spring to be bend back and would prevent even correct pin from going in. Have never tried to bend back to shape.

Rooster1262 · Jun 30, 2013

Without question that makes perfect sense. Now when I look back at this mechanism I can see how the Ferguson System Principal works. I read the article.
What it basically means I have the wrong pin. But as you have indicated by modifying pin it will slide into hole.

Thanks
It's been bugging me for a while. Nothing like thinking outside the box.

Three point linkage

Rooster1262

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rrlund

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Pycoed

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paul

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rrlund

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vapet

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Rooster1262

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