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log grapple design

Started by Case, February 02, 2012, 08:48:57 PM

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Case

i need to build a small grapple with around a 5000-6000 lb capacity.  After searching through the different styles I notice that there seems to be 2 main designs. 
One has the hydraulic cylinder set up so it only pushes on the top of one tine, and a link arm attaches to the other arm causing it to close.
The other has the hydraulic cylinder attach to the top of both tines, again a link arm attaches each tine so they close at the same rate.
Is there any reason to use one design over the other?  And can anyone get pics of grapples that they have, i need some more ideas on how to design everything so it actually works. Also, i am designing this in Inventor which so far is pretty easy.

Autocar

Case eather one are good grapples I believe John Deer has one cylinder and Essco has two cylinders. What are you going to put it on ?
Bill

Case

its going on a Hiab 174 knuckle boom, which is going to be mounted on a gooseneck dump trailer that I still need to get, but I need to sell my bumper pull dump first.
made more progress designing the grapple, just lots of trial and error.

Autocar

Case a grapple off of a 110 Prentice would work great on your Hiab, not sure where your located but Upper Michigan use to be loaded with them. Check some wreaking yards in your area ,alot of older junk yards here in Ohio have old Prentices they use to load junk with.
Bill

redlaker1

I have a valby grapple and rotator for my mini excavator,   its the single cylinder bypass style..     havent had a chance to use it too much yet,  but from the little bit I have I found it worked really well.    it will squeeze down to a 1.5inch round stick which is nice.   
seems to be well built too,   would be a good one to look at for ideas if you are building your own.      mine is the 36inch model

Piston

I'm glad you posted this, I was curious about the reasons for the differences as well.  There seems to be a lot of talk about grapples on here lately  ;D

Redlaker,
Do you think your grapple could be used as a small scale log skidder grapple?  for lifting and skidding?  I was told by valby that the GR36 may not hold up under pulling forces. 

-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

redlaker1

I think the grapple could be used for skidding..   it seems tough enough,    doesnt baileys sell tractor grapple setups with the valby grapple?   

I am not sure about the rotator though,   not sure if the internals of that would be strong enough for the side loads that skidding would bring.     but I dont think you would need a continuous rotator for skidding anyway.

as for building a DIY grapple,   the valby design looks to be the most complicated   with more joints and pins and bushings than the other style


Stephen Alford

   One consideration is tractor hydraulics are not touch sensitive. When lowering over a log or tree stems you are trying to close and lower at the same time.  You will likely be using different levers but trying do do it with one hand as your in the half pike position looking over your shoulder.  This can be a bit awkard and with the quick hydraulics often times you will grab roots or part of the stump. The terrain is mound and pit here even more so around the stump.
   The continous grapple has to holes drilled the length of the shaft  for the oil to travel allowing for the rotation. These shafts can be bent. This is evident where the hoses go  into the shaft for rotation, they will weep when the shaft gets tweaked, the holes go oval. This may not be an issue with the bigger rotation grapples.
    To make it easier to pick up a grab and  work in a thinning without damaging residuals  a piston was put on the backbone.  :)

 
logon

Piston

Case,
What are you going to put the grapple on?
-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

Case

my grapple is going to be mounted to a Hiab 174 knuckle boom. That will be mounted on a yet to be purchased goose neck dump trailer.  The whole think will be powered by a 10hp (i think) kohler gas engine driving the hydraulic pump.  the knuckle boom came with the engine and pump and I have not had a chance to look it over very well.
I am located south of Grand Rapids, MI so there is not to much logging go on around here, so i have been looking all over the net for different designs to get ideas off of.
thanks for all the help so far.

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