keep breaking pins in my grapple

[grapple man]

Thanks, I have a lot of pictures of this fantastic machine.

Since you are breaking pins from the cylinder force while clamping, I would plug a gauge into the extend coupler and see what the pressure is. 3600 psi on my 6 tine 5" cylinder is 70,686 pounds of push.

Does the 10 tine wide use a 5" cylinder?

No ten tine is still the 4x8 same cylinder on the 6 tine. what make is your monster grapple. i would like something like that to use for cleanup of small sticks and little brush

 

[Xfaxman]

No ten tine is still the 4x8 same cylinder on the 6 tine. what make is your monster grapple.

Loflin Fabrication: Loflin Fabrication

i would like something like that to use for cleanup of small sticks and little brush. Yep, that is why I got it, I had the 6 tine, but it won't do the little stuff.

This was the best deal at the time I bought mine.

New Loflin Large Monster 84" 7' Grapple Root Rake Skid Steer Loader Bobcat Cat | eBay



My 72" weighs 1184 pounds, according to the crane scales.

 

[Xfaxman]

You may not want the 7' grapple, I was thinking of another thread with a 7' wide tractor.

Here is the 6' link: New Loflin Extrem Monster 72" 6' Grapple Root Rake Bucket Skid Loader Holland | eBay

 

[grapple man]

You may not want the 7' grapple, I was thinking of another thread with a 7' wide tractor.

Here is the 6' link: New Loflin Extrem Monster 72" 6' Grapple Root Rake Bucket Skid Loader Holland | eBay

No I am interested in the 7 or even 8 foot grapple. I need something to sweep areas clean as fast as possible. I get called quite abit to clean up after dozer work.

 

[TomSeller]

As expected you are working the grapples as designed. If they are designed to crush concrete they should be able to crunch brush and trees. Curious if Sidney Manufacturing got back to you on their advice. If the pins are the intended point of failure then I might switch to a lynchpin style pin, grease up periodically and keep plenty on hand and swap them out on the fly without having to get the wrenches out. There is a common line of thinking that grapple hinge points will never wear out a without grease zerk pin, kind of like the balls on the end of 3 point arms.

 

[Coyote machine]

I'm thinking you need a different machine, say a trackhoe with thumb, or similar. Breaking pins on a regular basis is a time and money waster, whether you or someone else is the operator. If you truly seek efficient operation of your equipment to the task at hand you need to select a piece of equipment suited to and capable of doing so with limited to no component failure as a goal. JMHO. YMMV.

 

[SPYDERLK]

View attachment 343688
I think with two cylinders on the single lid, the force at the pins from the cylinders would be the same as if it had one cylinder. The cylinders are in parallel, so the pressure is the same in each one. Any force transferred back through the lid would still be the same in each cylinder.

I have had the Six Tine version since January 2011. It has pins with grease zerks, guess I need to check for slop.

It will break concrete! Squeezed too hard.
View attachment 343700 View attachment 343701

This is the other half, notice the fresh break.
View attachment 343702 View attachment 343703

Here is a lot of force on one upper tine.
View attachment 343704

It has never broken a pin.

Thanks, I have a lot of pictures of this fantastic machine.

Since you are breaking pins from the cylinder force while clamping, I would plug a gauge into the extend coupler and see what the pressure is. 3600 psi on my 6 tine 4" cylinder is 45,239 pounds of push.

Does the 10 tine wide use a 5" cylinder?

You must be assuming that supply pressure is breaking the pins. Yes, that would apply equal force to eachcyl. Clamping force would double but would be shared equally by the 2 cyls. Thus pin force would be the same ... and any increase from prying would be shared.

However 45000# from a 4" cyl will not double shear even a low grade 1" pin much less Gr8. Pry forces due pushing and lifting things causes forces to go higher. Still, with double shear around 160000# on 1" Gr8 youre going to have to have a pretty poorly designed shear joint to fail the 1" pin on a single cyl unit prior to pretzling the grapple. A solid pin extending completely thru a joint that has closely spaced shear points will stand the strain. If the shear points are not closely spaced a larger pin is surely called for.
larry

 

[Xfaxman]

i will answer the questions in no particular order. When we break the pins we are doing various things. I am usually the operator and I am also the owner. So with that said I have to pay for my repairs, but i also have to pay for my repairs. What I mean by that is I work my equipment ten times harder than I would expect anyone else to do. So I break pins at different times. Sometimes crushing a tree into submission so I can pick up one or two more and take to the burn pile. Other times when I have ten hedge posts in the grapple and squeezing them so i can take off from the pile to the trailer. Time is important to me and i buy the heaviest attachments I can find to handle the abuse. I know I am going to abuse them, and I buy from a company that assures me they build them to take the abuse. Yes I have the grapples mounted on T770s which are within spec for the grapples. The holes are not egged out, just a little over drilled I will mic them this weekend to see what size specifically i need to fill the void. I appreciate all the input and ideas. The reason it bothers me so much is that when i had the more narrow grapple which we still use 7 years later we rarely break pins, but getting almost twice as wide would add amazing amounts of flex and torque when hauling hudge loads which is my goal with every grab.

You must be assuming that supply pressure is breaking the pins. Yes, that would apply equal force to eachcyl. Clamping force would double but would be shared equally by the 2 cyls. Thus pin force would be the same ... and any increase from prying would be shared.

However 45000# from a 4" cyl will not double shear even a low grade 1" pin much less Gr8. Pry forces due pushing and lifting things causes forces to go higher. Still, with double shear around 160000# on 1" Gr8 youre going to have to have a pretty poorly designed shear joint to fail the 1" pin on a single cyl unit prior to pretzling the grapple. A solid pin extending completely thru a joint that has closely spaced shear points will stand the strain. If the shear points are not closely spaced a larger pin is surely called for.
larry

I am going by what grapple man said in post #25, he hasn't indicated any external pushing or lifting forces are involved.

These grapples are very heavy duty, the 6 tine is 44" wide and weighs 945 pounds.

the tines are 1 inch thick.

Mine was a demo, here is is on the pallet, the day I received it.

It uses pins, not bolts, on the cylinder clevises.

The 10 tine only has 1, 4" diameter cylinder, same size and geometry as the 6 tine.

 

[TomSeller]

Cylinder diameter the same?

 

[Midniteoyl]

Well, main thing to do first is get rid of the slop..

A 'weaker' bolt like a grade 5 would tend to distort and bend before shearing suddenly like a grade 8 and would give you a chance to inspect and replace it during down times instead of in the field.