Mounting pivot points?

[perry]

I'm installing a grapple arm and hyd. cyl. on my homemade stump bucket, Is there a formula for mounting the pivot points?. I have the grapple arms mounted with just a tack weld, have not tack welded the cyl. mount as yet.
I took measurements from a friends grapple bucket and here is what I came up with.... The rear mount for the hyd. cyl. is 3 in. back and 7 inches up from the grapple arms mounting position. I used these measurements when I raised and lowered my grapple arm trying to determine correct cyl. mounting position. but something is not quite right as there is only a 8 in. difference between raised arm and lowered arm?. I guess??.
My (good) grapple arm came from a half damaged bobcat grapple bucket.

 

[Tazza]

Is it because your rams have a smaller stroke? thats the only reason i can think of that would cause the grapple arms to not open up far enough. 3" out from the pivot point should provide some decent opening and more than enough down force.

 

[perry]

Is it because your rams have a smaller stroke? thats the only reason i can think of that would cause the grapple arms to not open up far enough. 3" out from the pivot point should provide some decent opening and more than enough down force.

His hyd. cyl. is a 10", I have a older 10" I am using to determine correct position but, It won't extend the full 10" between mounting points?. Now, the original cyl. mount my grapple arm was not touched which might be the problem?.

 

[perry]

His hyd. cyl. is a 10", I have a older 10" I am using to determine correct position but, It won't extend the full 10" between mounting points?. Now, the original cyl. mount my grapple arm was not touched which might be the problem?.

Here ya go Tazza, sorry I forgot how to attachment pics?. Don't mine the rust, it rained right in the middle of working on it.

http://i170.photobucket.com/albums/u253/perrynboo/004640x480-1.jpg
http://i170.photobucket.com/albums/u253/perrynboo/003640x480-1.jpg
http://i170.photobucket.com/albums/u253/perrynboo/002640x480-1.jpg
http://i170.photobucket.com/albums/u253/perrynboo/001640x480.jpg

 

[Tazza]

Here ya go Tazza, sorry I forgot how to attachment pics?. Don't mine the rust, it rained right in the middle of working on it.

http://i170.photobucket.com/albums/u253/perrynboo/004640x480-1.jpg
http://i170.photobucket.com/albums/u253/perrynboo/003640x480-1.jpg
http://i170.photobucket.com/albums/u253/perrynboo/002640x480-1.jpg
http://i170.photobucket.com/albums/u253/perrynboo/001640x480.jpg

I understand you now, the problem i see could be because you need to attach the base of the cylinder a little further back on the top of the bucket. The pivot point you have on the graple looks ok, i would just adjust where the base of the cylinder mounts, you need it further back to the machine than the pivot point for the graple arms. Does that make sense?
I'm in no way an expert on graples.... Hopefully thats the information you need.

 

[perry]

I understand you now, the problem i see could be because you need to attach the base of the cylinder a little further back on the top of the bucket. The pivot point you have on the graple looks ok, i would just adjust where the base of the cylinder mounts, you need it further back to the machine than the pivot point for the graple arms. Does that make sense?
I'm in no way an expert on graples.... Hopefully thats the information you need.

Yes, the cyl. pivot mounts 3'' further back than the grapple mounts, and 7'' vertical. I'll play with when it dries out a little and see what I come up with?.
Thanks

 

[skidsteer.ca]

Yes, the cyl. pivot mounts 3'' further back than the grapple mounts, and 7'' vertical. I'll play with when it dries out a little and see what I come up with?.
Thanks

It looks to me that your losing the 2" because the grapple arm does not close enough. On the original grapple, I'd think that the top of the grapple arm and the floor of the bucket are parallel when the grapple is closed.
On you bucket the grapple can't close as far because the tines are contacting the edges of your bucket which are curved up.
I'd trim the points on the grapple to where it closes to give the 10" stroke, and maybe weld some small stoppers on the floor of the bucket to prevent over extending the cylinder.
Ken

 

[perry]

It looks to me that your losing the 2" because the grapple arm does not close enough. On the original grapple, I'd think that the top of the grapple arm and the floor of the bucket are parallel when the grapple is closed.
On you bucket the grapple can't close as far because the tines are contacting the edges of your bucket which are curved up.
I'd trim the points on the grapple to where it closes to give the 10" stroke, and maybe weld some small stoppers on the floor of the bucket to prevent over extending the cylinder.
Ken

You are correct Ken, that didn't dawn on me?. I knew there was a formula so I called one of the major attachment manufactures and ask for the engineering department. The guy was very helpful and provided the following....
He said to pay attention to the 4.60 and 2.10, when you increase these numbers the clamping force increases as well.
http://i170.photobucket.com/albums/u253/perrynboo/img014.jpg