How are FEL lift capacities measured?

[toxcrusadr]

I was talking to my dealer about the L4600 I recently bought (not from them, bought direct from orig owner). This all started when I was looking at pallet forks and the dealer said I should get the 3000 lb cap ones they sell and not 2000 because I could bend them with a load that the tractor can actually lift. I thought the lift capacity was something like 1800 lb but he said it was over 2000. I probably don't understand the terminology. It has an LA764 loader.

The specs say:

Pivot Pin, Max Height 1684 lb
500 mm Forward, Max Height 1263 lb
Pivot Pin, 1500 mm Height 2154 lb
500 mm forward, 1500 mm height 1726 lb

I am not sure what the 'pivot pin' actually is. I did a little web searching on how these specs are determined, hoping to find a diagram, and did not. Is it at the end of the loader arms, where the bucket is attached?

Why do some tractors have a rating for '___ inches behind the pivot pin' ? How do you lift from behind the attachment point?

And once I have all that straightened out...this seems to indicate I can lift 2154 lb off of the pivot pin location but only to a height of 1.5m, correct? I assume the lift capacity drops as you go higher because of the geometry of the arms as they stretch up?

 

[toxcrusadr]

You know, that was kind of a dumb question on my part. I have a manual for the loader and it does identify where the pivot pin measurement is made. Duh. (for anyone else wondering, yes it is the attachment point at the bottom rear of the bucket.)

That leaves only the questions about why the capacity changes with height, and why some tractors have a 'behind' measurement.

 

[Aluthin]

It's to do with the lever affect the fulcrum is your front tyre the closer the load is to the fulcrum the more you can lift without tipping the tractor the higher you lift the load the big the lever effect as you have increased the distance of the load from the fulcrum so the same load would then tip the tractor. The max weight rating of the front axle also comes into effect as if I remember my physics correctly a force pushing down on a lever is increased the further away from the fulcrum the greater the force at the fulcrum ie front wheel......hope that helps [emoji41]

Sent from my MotoG3 using Tapatalk

 

[toxcrusadr]

That sounds like a reasonable explanation to me. Thanks!

 

[bxray]

You can use the torque formula to calculate weight lift.

Multiply the weight at the pin by the distance to fulcrum.

Now if you add forks or boom to the bucket just divide the new length using the same scale (i.e. inches) by the new distance and you will get your weight at that point.

Ray

 

[toxcrusadr]

Ah, very clever.

Someone said "Give me a proper lever, and a fulcrum, and I can move the world." I wonder if that was Mr. Kubota?

Well, it coulda been!

 

[scdeerslayer]

Assuming the loader will only lift 2154 lbs (could lift more??), by the time you add the weight of the forks & frame you'll lift less than 2,000 pounds on the forks, plus add the width of the frame that pushes the load out a few inches and you're even less. Just for lifting 2,000 is probably all you would need, but you might want the heavier forks if you may use them as a lever for prying out stumps or rocks. If the weight and price of the 3,000 isn't much more just go with them for good measure.