keep breaking pins in my grapple

grapple man · Oct 31, 2013

TomSeller said:
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.

yes i noticed this immediately with the grapples. And when i started breaking the pins, and the company wanted $30 a piece for them i started buying my own grade 8s drilling a hole in them and putting a lynch pin in. i grease them about every two days if they ever manage to last that long.

grapple man · Oct 31, 2013

Midniteoyl said:
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.[/QUOT

I have tried some grade 5 pins, and no they did not break trouble is just as you said they bend. And beating a bent bolt out in the field is a major pain in the ***** so back to grade 8s.

grapple man · Oct 31, 2013

everyone,
I just wanted to take a minute on this rainy morning and tell everyone how impressed and grateful i am for the warm welcome and great responses i have received from this site. I truely do appreciate it. I will be measuring hole this weekend. If i need a bigger bolt and need to drill out the cylinders i will get that done as soon as we finish this job and get back to the shop. Then i will be bolting it down tight and try that. i will let everyone know how it works over the next few weeks. look forward to helping others with issues if my expertise allows. thought you guys may be interested in this little trick we tried the other day while cutting. this was a really thorny -thorny locust. we had killed it the year prior during tsi work. my partner stuck a few peices of feed sack into the thorns about 2 cups of diesel which weren't needed and lite it. was pretty fast i couldn't get camera going fast enough

CJONE · Oct 31, 2013

CJONE said:
Install a cross over relief for the clamping cyls. Adjust it down to where it clamps with enough force. But it will allow the grapple to release when the operator gets it into a bind. My guess is this is what is happening with the wider grapples. Cheap fix and gives you insurance as to abuse. CJ

Does this not make sence?

Xfaxman · Oct 31, 2013

CJONE said:
Does this not make sence?

It did to me, I put one on my old tree shear, set it to not go over 2500 psi.

I suggested that he should check the pressure, no tellin how much is there!

Its got to be too much if it is breaking the bolts.

grapple man · Nov 1, 2013

Xfaxman said:
It did to me, I put one on my old tree shear, set it to not go over 2500 psi.

I suggested that he should check the pressure, no tellin how much is there!

Its got to be too much if it is breaking the bolts.

the pressure on my system runs from about 3425 to 3490. the pins rarely if ever break when i am clamping down on stuff they break when carrying or pulling. im sure they are being weaked all the time by varying aspects of the grapple functions, but when i am chrushing limbs together on a tree it doesnt' pop at that instant.

CJONE · Nov 1, 2013

grapple man said:
the pressure on my system runs from about 3425 to 3490. the pins rarely if ever break when i am clamping down on stuff they break when carrying or pulling. im sure they are being weaked all the time by varying aspects of the grapple functions, but when i am chrushing limbs together on a tree it doesnt' pop at that instant.

That is exactly what my post stated, a crossover relief will allow the cylinder to relieve even with the lever in nutral or locked position. That is why I suggested it. You can set the relief at 3500psi and when you load the cyl beyond that it will relieve, the way your setup is now it will not, so something has to give. CJ

SPYDERLK · Nov 1, 2013

CJONE said:
Does this not make sence?

Yes. It does when you can find a "good" pressure to set the cross port relif at ... AND it has no leakage. Otherwise you will get relaxation of the clamp force and be dropping things. Absent some seepage at the cross port relief, a setting of roughly twice the relief pressure used on the supply side would probably prevent most nuisance relaxation during pressure spikes caused by pry forces on the grapple.
larry

Xfaxman · Nov 1, 2013

grapple man said:
the pressure on my system runs from about 3425 to 3490. the pins rarely if ever break when i am clamping down on stuff they break when carrying or pulling. im sure they are being weaked all the time by varying aspects of the grapple functions, but when i am chrushing limbs together on a tree it doesnt' pop at that instant.

Where does it break?

Always in the same place?

CJONE · Nov 4, 2013

SPYDERLK said:
Yes. It does when you can find a "good" pressure to set the cross port relif at ... AND it has no leakage. Otherwise you will get relaxation of the clamp force and be dropping things. Absent some seepage at the cross port relief, a setting of roughly twice the relief pressure used on the supply side would probably prevent most nuisance relaxation during pressure spikes caused by pry forces on the grapple.
larry

These "pry" forces are what is breaking the bolts, so he will have to experiment a little to see where the setting would have to be. As far as leakage most units are rated a drips per min. And I believe the units I have are zero to 1. So a non issue with a grapple. CJ