Calculating FEL Lift Capacity

[LD1]

I believe you are correct on the metric size cylinders with 45mm probably spot on.
Here's one of many FEL spec charts showing the various nomenclature:
Farm King - Front-End Loaders
The "breakout force" seams to be misunderstood in some cases.

Yep, and all of those loaders show a breakout force of about double the max height rating. And a lift spec to 59" being somewhere in-between.

So your loader is roughly twice as strong down low as it is up high. People always look at the up high spec. And somehow when their loader exceeds expectations downlow that gets conveys as the loader being "underrated" instead of just realizing the fact that they were reading the wrong spec to begin with

 

[davedj1]

You guys are way better at the math than I am. I use this calculator.
Hydraulic Cylinder Calculator (Angle Calc)

 

[gladehound]

So I'm getting about 1350 pounds at the bucket pin in the top position at 1600 psi using the 45mm ID. Subtract the bucket and loader arms and the ~800 pound spec seems about right.

 

[LD1]

So maybe I overlooked it. And do really enjoy these threads where we talk physics, trig, geometry, math, etc......but just what were you questioning? And what was the reason for taking the time to draw all this out in cad and doing the math?

 

[gladehound]

You guys are way better at the math than I am. I use this calculator.
Hydraulic Cylinder Calculator (Angle Calc)

After you use that calculator I think you still need to multiply by 2 (number of cylinders) * the ratio of the distance to cylinder over the distance to the bucket pin.

 

[npalen]

So I'm getting about 1350 pounds at the bucket pin in the top position at 1600 psi using the 45mm ID. Subtract the bucket and loader arms and the ~800 pound spec seems about right.

Yes. The difference between the 2.000" cylinder bore and the 1.770" (45mm) reduces the force down to about 62% as you probably calculated. Big difference!

 

[gladehound]

Thanks npalen for starting this thread. I never used the moment arm method for this type of calculation before and like it much better than using the "sin" function. So thanks for showing me a new method.

LD1 - I think npalen's original question was because the ~2700 pounds he calculated wasn't close to the ~800 pound spec. We learned that loader position and cylinder ID (and weight of the loader / bucket) were the culprits.

 

[npalen]

So maybe I overlooked it. And do really enjoy these threads where we talk physics, trig, geometry, math, etc......but just what were you questioning? And what was the reason for taking the time to draw all this out in cad and doing the math?

As mentioned in my post #1 above, I was trying to figure out the factory relief valve setting on the loader. After doing all the drawing and using 1500 psi as a starting point, I found the relief setting of 1638 psi (IIRC) for the loader in the B9200 tractor manual.
Incidentally, I did up the relief to 2000 psi by putting a .012" shim under the relief valve spring. I know, this may not be wise as far as loader and tractor longevity, but the bucket is so small that it doesn't require that much psi. It's not going to take any more psi to carry a full bucket now than before changing the relief. Trying to lift too much weight with a chain, however, is a different story and requires some judgement. Guess who gets to fix it if I break it.
What it does is give me more "breakout digging power" when loading the bucket and also sends this higher psi on to the rear remotes via power beyond where it can be utilized.

 

[oosik]

I've lifted a chunk of pine log - 20' x 24"(ave) - weighing around 2900# -with my grapple with no difficulty. The only problem was - I didn't want to lift it high enough to clear a gate in my barbed wire fence. I get real nervous when dealing with heavy loads and soft ground. My chain saw made this situation manageable.

I would guess you could get a pretty close "real life" max lift by putting bags of a heavy material(sand, gravel, cement) in your FEL bucket - if your bucket is big enough to hold that much. I really doubt I could get 30 bags of dry cement in my bucket. Besides, lifting a pine log with the grapple is so much easier than loading/unloading 30 bags of anything heavy.

 

[npalen]

Thanks npalen for starting this thread. I never used the moment arm method for this type of calculation before and like it much better than using the "sin" function. So thanks for showing me a new method.

LD1 - I think npalen's original question was because the ~2700 pounds he calculated wasn't close to the ~800 pound spec. We learned that loader position and cylinder ID (and weight of the loader / bucket) were the culprits.

You are welcome. I've always used the moment arm method as it's just easier for me even when doing some fairly complex mechanisms.