Grapple Design

[dtd24]

Let me know what you guys think. Still in the design stage, but she is close. I made this to fit my current bucket even though it's kinda small. I want this to be on and working for spring cleanup, so I figured in order to keep the budget down I will keep the small bucket for now and build a root bucket w/ grapple later down the road.

 

[shaley]

Why did you use such a long hyd cyclinder.

 

[kenmac]

It may be me ,but when I click on your picture link .nothing happens .as in I can't get your pics. to open

 

[dtd24]

shaley
that was the smallest I could locate. Maybe you have another source? I wanted to keep it to be 2500 psi. I went to TSC and measured this one all up. I did search on the net a bit, but that was awhile ago. A smaller cylinder would help me straighten that arm out.

kenmac
the files are adobe files. If your computer doesn't have it you can get it for free @ Adobe - Adobe Reader Download - All versions

DaveD

 

[moeh1]

I haven't gotten serious yet , but want to fab one also. You might want to mock that design up in cardboard or pine and see if that gives you the area you want to grab. I am mostly interested in brush piles, and I would have (naively) thought that the "area being captured" would be bigger. Would have arced the arms and used a shorter cylinder fmounted farther back. Would be great to have someone who is highly familiar with them weigh in.

Shaley - love your end quote! Hope you last a long time, but hoping to eventually see your wife's garage sale sign!

 

[jinman]

The problem I see with your grapple is that the front claw portion may get in the way of your using the bucket for normal dirtwork. I think you will be hitting it on a lot of things unless you detach it for normal FEL uses.

That's just my opinion from your side elevation drawing. The other PDFs were too large and slow to download on my machine.

 

[MadReferee]

You are going to have a difficult time finding an off the shelf 2" x 6" cylinder with a retracted length of 20". The closest you will find is a 2" x 8" tie rod cylinder with a retracted length of 20 1/4".

I would suggest that you redesign your grapple around the commonly available cylinders. Most grapples use a 2" x 6" cylinder with a 16 1/4" retracted length. I tried the 2" x 8" on mine and went back to the 2" x 6" as it offered better opening and closing geometry.

Price shouldn't be an issue as they will cost between $65 and $100 each from Surplus Center. They have both 2500 and 3000 psi cylinders.

 

[shaley]

Here is the link Mad is talking about.
Surplus Center Item Detail

Poke around on the Hydraulic page and see what fits.

 

[3RRL]

dtd24,
I don't see a big problem with the basic concept. As mentioned, in order to use a stock hydraulic cylinder you may have to mess around with the pivot point locations is all. And like Jim pointed out, the jaw should open more so it won't get in the way when you are not using it.

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.

Please don't take offense but this is my observation....I know how hard it is to hear about what you are making ... believe me. I think you need to use a more conventional shape jaw like the curved ones or angled ones that don't go towards the back so much.

 

[dtd24]

I never take offense to constructive criticism. I have never even used a grapple, so I am using the information from this site and from grapple equipment website for my design. I looked at it in depth last night (so I could sleep !!) , and I agree with alot of your comments. I am working on a revised design. I will post soon. My job has been stealing alot of my design time. I was most concerned about the mouth opening being too small. My new design is wide open. I love the weapon look of this thing !!!! Drawings are on the way.

 

[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.