Grapple Design

[dtd24]

Alright, digesting all of your comments and re-thinking this project a bit. I have come up with a better design I think. I used a 2x6x1.125 Fieldmate Double Acting Clyinder from Surplus Center (Item # 9-6070-206) which is smaller than my first design by 4". I opened up the "mouth" of the grapple by about 9". This should clear the grapple from getting in the way when not using it, and still be effective. Do you think the pressure on the braket holding the arm at the bucket will be a problem since I pushed it out more?

Let em rip boys....... ( nicely please )

Scale is 1 1/2" = 1'-0"

DaveD

 

[dtd24]

Ooooooppppps
forgot to upload...... too excited!!!!!!

 

[woodlandfarms]

Moss Road in the PowerTrac group built one as well I think. The only thing I wonder is if your hydraulics are too close to the pivot point of the claw and will cause binding on the return motion... I know he had some issue with that I believe..

Carl

 

[3RRL]

Yeah,
I agree about cylinder position vs the pivot points. You might want to raise the pivot point on the bucket lip about an inch or so. That will give you a little better leverage to open. Right now, the centerline of the cylinder is pretty close to being in line with the 2 pivot points. I see the rear one is slightly above that line, but you want to make sure it pivots up and not just "retract" your jaw into the bucket. Raising that rear one should make just a little difference in jaw opening but will make it pivot better for sure.

I like the larger opening a lot! You can see now that any debris will most likely fall out of your jaw design much better. I'm still debating how well the jaw will perform with that rearward angle though. I don't recall any jaws that have that feature. There might be a reason for that? I've seen them with like a 90° angle though. In any case, you can always change the shape later if it doesn't do what you want.

Starting to look really good now.
Thanks for sharing.

 

[3RRL]

dtd24,
If it helps any, this is what my grapples look like.

 

[IslandTractor]

What concerns me is the geometry of your grapple jaw. Specifically, the shape where it comes backwards like that, and the sharp angle/corner in it. With the jaw going back like that, as it closes onto "stuff", it may not "drag" or "roll" or push the shrub, rocks, logs back into your bucket. I'm not sure, but it looks like the part going back (on the jaw) might get in the way of the stuff you are grabbing? Second is that if you do get stuff inside those jaws, like shrubs, they might stay there. It looks like it may be hard to dislodge the stuff once it's behind that sharp corner.

I second 3RRL's concern. I don't see any advantage to the acute angle you drew into the upper grapple jaw. A slightly bowed out upper jaw that does not protrude beyond the bucket lip would have the advantage of slightly increasing capacity especially on a bucket grapple set up where your bucket sides will limit your ability to load longer branches etc.

 

[IslandTractor]

dtd24,
If it helps any, this is what my grapples look like.

And, if I were to fabricate something for a bucket, I'd modify and simplify 3RRL's design to have just a single wider upper jaw that covered maybe half the bucket. There are a few times when two jaws would be helpful but almost anything can be securely held by a single jaw. Check out the ATI grapple kit GK-4866. That comes pretty close to what I'd do with a three pronged upper jaw that covers almost 50% of the bucket and is bowed out to increase capacity.

 

[dtd24]

do you guys think a 1x6x.5 cylinder would be OK. I have a JD 1070 w/ a 440 FEL. I'm not sure of the lifting capacity. The cylinder size is only 12.5 on above. Seems pretty small though.

Surplus Center Item Detail

 

[shaley]

do you guys think a 1x6x.5 cylinder would be OK. I have a JD 1070 w/ a 440 FEL. I'm not sure of the lifting capacity. The cylinder size is only 12.5 on above. Seems pretty small though.

Surplus Center Item Detail

I think that cylinder is too small. Most units use 2" or 2.5" because the geometry of the claw when closed cause the moment arm to dimenish to the point of almost zero force. Calc the moment arm length and see or post the layout and we can help you.

 

[IslandTractor]

do you guys think a 1x6x.5 cylinder would be OK. I have a JD 1070 w/ a 440 FEL. I'm not sure of the lifting capacity. The cylinder size is only 12.5 on above. Seems pretty small though.

I'd defer to MadRef or 3RRL on cylinder size but I will point out that all the cylinder needs to do is close the grapple jaw. That might seem obvious but the point is that you are not trying to match your FEL's curl power or anything like it. It is nice to be able to crush the brush but that would only require a few hundred pounds of pressure. Mostly you just want it to close and stay closed.