Help with cylinder placement on grapple

   / Help with cylinder placement on grapple #1  

Stomper

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Saskatchewan, Canada
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2017 Kubota L2501
I am looking for help in trying to find the locations to mount a cylinder on my grapple. I have a 12” c to c closed cylinder with a 4” stroke. What is the best/easiest way to figure this out without using a computer.
The top cylinder mount and the grapple cross brace are only tack welded and can be moved easily if needed
 

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   / Help with cylinder placement on grapple
  • Thread Starter
#2  
I have found this, specifically post #4 but I don’t fully understand what he is saying. If someone could help explain it that would be great
 
   / Help with cylinder placement on grapple #3  
Either you have to do a bunch of math to calculate open and closed positions or take a piece of wood with pin holes to simulate a fully extended and fully retracted cylinder and use those for your gauges.
 
   / Help with cylinder placement on grapple
  • Thread Starter
#4  
Either you have to do a bunch of math to calculate open and closed positions or take a piece of wood with pin holes to simulate a fully extended and fully retracted cylinder and use those for your gauges.
What’s the math way. Is there a formula for this
 
   / Help with cylinder placement on grapple #5  
That cylinder is way too short to give you a half decent opening height and still close all the way.
 
   / Help with cylinder placement on grapple #6  
When I built my grapple or thumb for my loader I calculated the open and closed angles using sine, cosine, tangent formulas based on knowing two of the sides of the triangle.

You should have distance from lid hinge to cylinder mount pivot points. Now it becomes a matter of determining what positioning of the cylinder provides max opening movement and adequate clamping force.

After multiple calculations I got a rough idea on the amount of movement possible and then used two pieces or wood representing extended and retracted cylinder length to very my math was close.

The huge unknown for me was clamp force required.

Probably better ways to calculate but I do not what the formula would be.
 
   / Help with cylinder placement on grapple #7  
Either you have to do a bunch of math to calculate open and closed positions or take a piece of wood with pin holes to simulate a fully extended and fully retracted cylinder and use those for your gauges.
Or you make a drawing to scale, and use a pair of compasses to determin where two radii meet at min and max stroke.
 
   / Help with cylinder placement on grapple
  • Thread Starter
#8  
Or you make a drawing to scale, and use a pair of compasses to determin where two radii meet at min and max stroke.
Can you please elaborate on this please. This sounds like what 3RRL was talking about in the link that I provided
 
   / Help with cylinder placement on grapple #9  
There is the time tested trick of using a couple pieces of PVC that emulate a cylinder...just get similar sized pieces of PVC where one fits in the other and drill some holes...

HD sells 2' sections of PVC...

Good Luck...
 
   / Help with cylinder placement on grapple #10  
What’s the math way. Is there a formula for this
 
 
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