Flexible top link for bush hog?

[have_blue]

</font><font color="blue" class="small">( Now I know the rest of the world can't be all wrong, so what am I missing here? If the tale wheel will freely follow the ground then whats the point? /forums/images/graemlins/confused.gif )</font>


One thing I can think of: Without a top link to limit tail wheel drop, if you run over a sharp hill (like a levee) the brush hog's front end could really gouge in deep.

Other than that odd situation, as far as I know, the top link's only purpose is to lift the brush hog for traveling.

Unrelated to actual mowing, the top link is real handy for lifting the bush hog up nice and high for blade sharpening. So I'm keeping mine.

 

[Syncro]

I didn't explain this right, I did not mean that I left the top link out. I still have the top link connected, just that its connected directly to the bush hog with a solid pin and does not use a flexible link. My point was that even with this 'solid no flex' 3 point hookup the rear wheel can still move freely up and down and pivots about the lower links.

Sorry about the confusion. /forums/images/graemlins/laugh.gif

 

[beenthere]

"What's the point?" I think you missed it. /forums/images/graemlins/wink.gif But no offense, you will some day have an aahhhh soooo 'awakening', as I did once. /forums/images/graemlins/wink.gif

 

[Soundguy]

I think you are missing some of the geometry. The hog cannot pivot onthe bottom links witht he rigid toplink in place. up pressure on the tail wheel should 'lift' the mower as the 3 links will allrise together. If the mower did actually pivot on the lower links.. the toplink would be bending...

Soundguy

 

[Farmwithjunk]

I've been following this thread since day one, with some interest. Now that everyone has had their say, I'll weigh in.

I have a Woods BB840 mower. It has built-in "flex" that allows the top-link "mast" on the mower to move, allowing the mower great flexability. With the mower in "mowing position", I set the top link to allow as much up-and-down movement as possible. The rear wheel could DROP as much as a couple feet with no trouble. It can also RAISE a couple feet. (mind you, this is a 7' mower. It's LONG. That exagerates the up/down distance over, say, a 5' mower)

So as to be able to RAISE the mower SAFELY over obsticles without dragging the rear of the mower over them, I employ the use of a hydraulic top link. When I need to raise the rear of the mower up high, I merely shorten that top link long enough to raise the mower, then return it to the desired setting before continuing.

By allowing so much "flex" I eliminate stress and strain on the 3-point linkages when crossing irregular terrain. By using the hydraulic top link, I eliminate the problems associated with "too much top link slack".

Works great, mows safley, and doesn't destroy equipment.

 

[Syncro]

<font color="blue"> The hog cannot pivot onthe bottom links witht he rigid toplink in place. up pressure on the tail wheel should 'lift' the mower as the 3 links will allrise together. </font>

Yeah you're right, again I did not describe it right. Even so, the back wheel does move relatively easy up or down.

All this aside, its still probably a good idea to have a little flex so as to ease the effort. I'm going to make up a flex link when I get a chance, even though I've never had any problems in all the years I've mowed without it, I think my little tractor will be happier.

Hey, and thanks to all for the discussions, I learned a lot. /forums/images/graemlins/laugh.gif /forums/images/graemlins/grin.gif

 

[rambler]

</font><font color="blue" class="small">( I posted this original question a while back, as to why the need for a flex top link. Today I had to mow the last pasture on our land so I hooked up my bush hog sans any flex top link, and before I started I decided to try a little experiment. I parked the tractor on level ground and lowered the hog. I next took a wood lever and proceeded to raise the back tire of the hog. Well, the deck just pivioted on the 3 pt lower links any easily moved up and down. So to my dumb eye it looked like the tale wheel would do the same on uneven ground, that is move up and down without any flex top link.

Now I know the rest of the world can't be all wrong, so what am I missing here? If the tale wheel will freely follow the ground then whats the point? /forums/images/graemlins/confused.gif )</font>

I don't understand, but I would like to. What you did - use a solid top link so your mower is solidly connected to the tractor 3pt on all 3 points; _and_ be able to lift up the rear of the mower with a bar more than an inch or 2:

Should not be possible. Can't be done.

The only possiblitiy I can think of is that your mower is designed with a flex link from the upper 3pt arm socket to the rear of the mower???? In that, the mower itself will swing up & down? This could have been designed in, or some stablizer arms could have been removed by you or the previous owner?

_Most_ mowers are designed with a ridgid, hard, unmovable framework from the mower deck to the upper 3pt socket. If you use a rigid upper 3pt arm with this, then the mower cannot pivot up & down as you describe. Law of physics and all. (With the fre-floating 3pt hydraulics, you can raise the mower up of course, but that is a parrallel raising, not a true, helpful pivot action that we are looking for?)

Now I'm not doubting you, and not trying to open a can of worms. /forums/images/graemlins/smile.gif

I'm just trying to understand? What you describe as working - should not.

--->Paul

 

[GuglioLS]

Very interesting - Here is my 2 cents worth:

To solve the problem of a "flexable" top link when mowing I installed a hydraulic top link, the valve has a FLOAT position. When mowing I place the valve in float and the cylinder extends / retracts as needed when mowing up & down dips. Works great. No chains, no removing / installing / adjusting various top links. Just move the hydraulic lever into the float detent and all is good.

 

[Syncro]

<font color="blue"> GuglioLS.......I installed a hydraulic top link, the valve has a FLOAT position..... </font>

Now thats classy! Yup, a very good way to go. Trouble is though I don't have a hyd top cylinder.


<font color="blue"> --->Paul ... you can raise the mower up of course, but that is a parrallel raising, not a true, helpful pivot action that we are looking for?</font>

True again, it is more of a verticle lift rather than a swinging pivot, but it did seem to move pretty easily. I used a 5' 2x4 over a block of wood and it lifted up as far as I had lever space. As I said, it seems that would be enough.

OK, I think I've worked this thread to death, don't know if anything was truely resolved. Fun disscussion though. /forums/images/graemlins/grin.gif

 

[RobJ]

</font><font color="blue" class="small">( <font color="blue"> The hog cannot pivot onthe bottom links witht he rigid toplink in place. up pressure on the tail wheel should 'lift' the mower as the 3 links will allrise together. </font>

Yeah you're right, again I did not describe it right. Even so, the back wheel does move relatively easy up or down.

All this aside, its still probably a good idea to have a little flex so as to ease the effort. I'm going to make up a flex link when I get a chance, even though I've never had any problems in all the years I've mowed without it, I think my little tractor will be happier.

Hey, and thanks to all for the discussions, I learned a lot. /forums/images/graemlins/laugh.gif /forums/images/graemlins/grin.gif )</font>


Unless there is something else no the rear wheel won;t move up and down. Maybe the complete 3pt is moving up and down with draft control or something. Otherwise it'll pick up the back of te tractor. These guys are trying to explain it as simple (and nicely) as possible.

 

[rambler]

</font><font color="blue" class="small">( --->Paul ... you can raise the mower up of course, but that is a parrallel raising, not a true, helpful pivot action that we are looking for?

True again, it is more of a verticle lift rather than a swinging pivot, but it did seem to move pretty easily. I used a 5' 2x4 over a block of wood and it lifted up as far as I had lever space. As I said, it seems that would be enough.

OK, I think I've worked this thread to death, don't know if anything was truely resolved. Fun disscussion though. /forums/images/graemlins/grin.gif )</font>


Ok. In my experience without a flex-link, when the tractor goes through a dip:

The front wheels enter, & the mower is hanging in the air, parrallel with the tractor, not parrallel with the ground. Either the front of the mower is digging into the dirt with the whole weight of the mower on it, or the grass is not being cut well because the mower is no longer parrellel with the ground it is over.

The front wheels come out of the dip, the rear wheels go in the dip. The mower now compresses, the tail wheel taking all the weight of the mower, and there is a bit of sissors-type compression of the whole 3pt linkage with the front wheels & rear mower tail wheel compressing the mower, the rear wheels of the tractor dropping down. Typically the rear of the mower wants to press into the ground hard, the front of the mower is trying to raise & not cut - tho that tiny compression force binds it from raising freely. In the end, the tail wheel leaves a mark, the grass is not cut well, and it just is a yuky deal.

I understand you may be able to coax the mower up in a parrallel action with a bar & block of wood while standing still, but in actual use in the real world when motion & compression forces are happening, that upward motion does not easily happen, & the parrallel action of the mower (to the tracotor, _not_ the ground) prevents smooth cutting.

A flex-link, even a small flex, will _greatly_ smooth all this out, preventing dig/ scrape marks on the sod, and a leveler, smoother cut.

Just my experience, not saying that is how it is or should be for everyone. /forums/images/graemlins/smile.gif

--->Paul

 

[N80]

I think you got it right. And that makes me wonder, did early 3pt hitch bush hogs not have any flexible/floating links at all?

The reason I ask is that my brother-in-law, a farmer who has his own tractor shop, had strongly advised me to avoid 3pt hitch type mowers and to only consider pull-type mowers for uneven ground. We had a heated discussion here about this 3 or 4 months ago. He cited excessive stress on the hitch and the mower mast when moving over rough terrain. Well, he was coming from the perspective of very large mowers and very old mowers. All of his equipment is big and old. So when I went against his advie and bought my LX6 he came over and looked at the floating link (see picture several posts up) and seemed to think it was just brilliant. I didn't ask, but I just wonder if he'd been thinking about older solid top links all along.

In any case, I think the JD floating link arrangement works extremely well on rough terrain _IF_ you have it set up properly.

 

[Soundguy]

</font><font color="blue" class="small">( So when I went against his advie and bought my LX6 he came over and looked at the floating link (see picture several posts up) and seemed to think it was just brilliant. )</font>

Perhaps true. I havn't seen too many older 'larger' mowers that were not pull type.. that is.. I've never sene an 'old' 8' or 7' 3pt mower.. etc.

Now.. on my new 10' 3pt mower.. the hitch itself has a built in floating link.. that makes for a decent smooth mow over moderately rough land.

Soundguy

 

[Soundguy]

Update.. While reading my 8n manual.. I came across a section that 'verbatum' refers to the 3pt linkage as "a built in safety feature". That's word for word from the manual.

I knew I had read it somewhere..

Soundguy

 

[firemanpat2910]

Some pictures in here are relevent to a new thread so I dug this up