Top link off center?

[Jims1025R]

I'm modifying my front mount snowblower to be three point hitch rear mount (so adding three point hitch fittings to the blower box). The lower two are easy do, but the single top link is going to interfere with the chute if I center it. But, if I go off center somewhat, it'll clear the chute fine. Has anyone any experience with the top link being off to one side? I'm thinking that as long as it is at least somewhat inside/between the two lower links, it should provide the necessary geometry?

Thoughts?

Jim

 

[mcfarmall]

My thought is if the location of the top link didn't matter, then there wouldn't be a need for an ASAE standard for 3PH geometry. I think I would find a way to keep it centered, even if it means re-engineering the lower links.

 

[Grandad4]

I think if the top link is off-center, the attachment will not keep the same lateral adjustment as it is raised and lowered. So the snow blower will tip slightly from side to side at different heights. Maybe not a huge problem for a snowblower (I dunno ???). You probably could adjust it to be level at ground level and call it good. I would be tempted to give it a try before putting time and money into some metalwork.

 

[IndyJay]

I'm modifying my front mount snowblower to be three point hitch rear mount (so adding three point hitch fittings to the blower box). The lower two are easy do, but the single top link is going to interfere with the chute if I center it. But, if I go off center somewhat, it'll clear the chute fine. Has anyone any experience with the top link being off to one side? I'm thinking that as long as it is at least somewhat inside/between the two lower links, it should provide the necessary geometry?

Thoughts?

Jim

Pictures?

 

[Halftrack]

You might consider a loop of chain back to a single piece to the top link. Assuming your blower has or will have shoes to ride on, allowing the top link to compress, lets the blower ride over the uneven spots. You will have to be a little more observant of the height of the lower links, as too low would tip the blower back. Good Luck.

 

[TractorGuy]

Aren't you going to a lower input speed? Just asking. Does your tractor have a two speed rear PTO?

 

[npalen]

I don't think the offset top link would matter provided it isn't so excessive as to cause the ball joints to "bottom out" because off the pins angle. Also would want to carefully check that the toplink isn't hitting the sides of the mount on the tractor. Would probably need to have the lower links restrained laterally enough to keep the attachment reasonably centered.
It depends a lot on how much offset you're talking.

 

[Leejohn]

Better check and make sure the pto turns right for the blower.

 

[Jims1025R]

Yup, I checked, everything turns the correct direction. It is evident that what had been a front mount blower on my JD650, was a converted rear mount blower from something else JD had build previously. It had a special gearbox to reduce from front PTO speed to blower speed without changing direction (idler gear, not evident until you take it apart). So, instead of gearing down from engine speed (roughly 2.5:1), I'm going to sprocket and chain up from rear PTO speed to blower speed (roughly 1:2). The desired blower (fan) speed is 1000 RPM.

That's the easy part. The lower three point links are also easy, as I've already made a cross beam for two 360 degree swiveling castors to replace the skid shoes (they dug in). The lower three point links go perfectly to that beam. The top link should be a little off center, so as to be beside the chute, rather than a complex and spindly structure to try to hold a centered top link half way along and behind a still off center chute.

I will put up photos when I have it all figured out. As I didn't even mount the blower last winter, for lack of snow, I'm not interested in buying a whole new three point mount blower, when I have an otherwise unused front mount blower just sitting here waiting for some creativity to make it rear mount!

 

[Leejohn]

Can you just tilt the top mount link fwd just so it well clear?

 

[Jims1025R]

Can you just tilt the top mount link fwd just so it well clear?

Not practical, still too much structure would have to be added to get it out and around the chute swing cylinder. And, the top arm of the 1025 does not shorten as much as the JD650 did. My home made vertical log splitter, I made for the 650, had a closer top link to get around the push cylinder. It fit fine on the 650, but will not sit vertically on 1025, with the top link most shortened. The 1025 appears to depend upon the top and lower links all being in the same vertical plane.

I plan to make my offset top link attach a bold on, so if I have been horribly wrong, I can unbolt, and rethink!

 

[PILOON]

Yup, I checked, everything turns the correct direction. It is evident that what had been a front mount blower on my JD650, was a converted rear mount blower from something else JD had build previously. It had a special gearbox to reduce from front PTO speed to blower speed without changing direction (idler gear, not evident until you take it apart). So, instead of gearing down from engine speed (roughly 2.5:1), I'm going to sprocket and chain up from rear PTO speed to blower speed (roughly 1:2). The desired blower (fan) speed is 1000 RPM.

That's the easy part. The lower three point links are also easy, as I've already made a cross beam for two 360 degree swiveling castors to replace the skid shoes (they dug in). The lower three point links go perfectly to that beam. The top link should be a little off center, so as to be beside the chute, rather than a complex and spindly structure to try to hold a centered top link half way along and behind a still off center chute.

I will put up photos when I have it all figured out. As I didn't even mount the blower last winter, for lack of snow, I'm not interested in buying a whole new three point mount blower, when I have an otherwise unused front mount blower just sitting here waiting for some creativity to make it rear mount!

The desired blower (fan) speed is 1000 RPM.????

My CUT has 3 PTO speeds and I tried my blower at 1000 RPM's.
Bad news, it would have shook itself apart in short order as the fan was not suitably balanced for that speed.

I then use my 700(ish) PTO speed and that was OK. (10 years now)
I did that as the 500 RPM performance was pathetic.

Actually the whole design problem is that the fan diameter is too small which I guess was to accommodate a wider range of pto powers.

 

[sandman2234]

Ok, first...I have never seen a snowblower, so take that with a pound of salt (not a grain, but a pound!!) Is it possible to have two points of attachment on the implement and bring them together and then make a centered top link? Would require getting a seriously shorter top link.
If a snowblower isn't a heavy implement, I doubt offsetting the top link will matter, as long as it is less than half a foot.
David from jax

 

[Jims1025R]

I got the 1000 RPM from doing math on the gearbox I removed. That value was substantiated by a reply from a three point hitch snowblower manufacturer, who very kindly gave me guidance, in part saying:

The fan on the 700587 needs to turn approx.. 1100RPM. Direct drive will be too slow and will not through the snow very far.

So I'm just working with the information I have, but knowing that direct drive of 540 to the blower will not work well for me. Happily, I don't need to throw the snow far, just away from the driveway, so I don't need optimum performance, just move the snow 20 feet. I guess that if it shakes, I'll have some balancing to do!

The snowblower weighs around 500 pounds (and they shake!), so my fittings must be robust...

 

[Jims1025R]

Conversion complete. I had to offset the top link about 6" to the right, to clear the chute cylinder mechanism. I removed the original gearbox which reduced from front mount PTO engine speed, and made up a chain drive, which about doubled the 540 PTO to get the best fan speed. Everything works very well. If winter turns out the way I would like, I won't even use it!

Began with.....

Finished product:

 

[SmallChange]

I don't think it should be much of a problem generally. I think it'd create an imbalance of forces acting on the two lower links, but only along the horizontal dimension, along which everything is very strong and rigid, so that wouldn't matter. It could add some twisting stress on a wide implement that might experience unbalanced forces -- such as a box blade with its rippers adjusted to only scarify the earth on one side and not the other.

I had a counterweight built from two very solid slabs of steel, that sat side by side on a repurposed drawbar. I had to put the top link on one or the other, so that was off center, maybe by about your 6", give or take. The top link kept the weight from pivoting forward or backward, and I could never tell that being off center made any difference at all, in my case.

 

[PILOON]

I don't think it should be much of a problem generally. I think it'd create an imbalance of forces acting on the two lower links, but only along the horizontal dimension, along which everything is very strong and rigid, so that wouldn't matter. It could add some twisting stress on a wide implement that might experience unbalanced forces -- such as a box blade with its rippers adjusted to only scarify the earth on one side and not the other.

I had a counterweight built from two very solid slabs of steel, that sat side by side on a repurposed drawbar. I had to put the top link on one or the other, so that was off center, maybe by about your 6", give or take. The top link kept the weight from pivoting forward or backward, and I could never tell that being off center made any difference at all, in my case.

All the forces are transmitted to the bottom arms/links.
The upper is merely a stabilizing link to keep the tool (blower) properly oriented , e,g.: parallel to the ground

Very few, if any 3 point attachments exert forces on the top (stabilizing) link.

 

[RickB]

I don't think the offset top link would matter provided it isn't so excessive as to cause the ball joints to "bottom out" because off the pins angle. Also would want to carefully check that the toplink isn't hitting the sides of the mount on the tractor. Would probably need to have the lower links restrained laterally enough to keep the attachment reasonably centered.
It depends a lot on how much offset you're talking.

Agreed.

 

[npalen]

All the forces are transmitted to the bottom arms/links.
The upper is merely a stabilizing link to keep the tool (blower) properly oriented , e,g.: parallel to the ground

Very few, if any 3 point attachments exert forces on the top (stabilizing) link.

A moldboard plow, for example, introduces a compressive force in the top link. That force is what operates the hydraulic sensing for draft control.
A top link wouldn't be necessary if there were no forces exerted on it. Right?

 

[RickB]

Very few, if any 3 point attachments exert forces on the top (stabilizing) link.

You really should know better than that.