Calculating FEL Lift Capacity

[PILOON]

Don't know all the math but my CUT will lift the rear clear of the ground when I have the bucket teeth jammed under a big rock or tree roots.
Tractor is 3000# plus loaded tired plus 300# rear weight so I presume loader is under 3000# range but close if I can flip the rock but not lift it.
How's that for critical math?
But I can always lift a full bucket of crushed stone or wet sand.

 

[JCByrd24]

A new-school loader may start at 15.....and at max height only be down to 7.5 degrees. Only a 7.5 degree loss of angle vs the 15.

But as a percent, They both lost 50 percent of their initial angle. And thus, both will have lost 50% of their power. Without having dimensions of several different loaders, of each design, and plotting them out to see what they do....its hard to say.

Mathematically your first statement that both lost 50% is not accurate, making your second statement very accurate. The nature of the trigonometry involved here is not linear and requires more math than comparing the percent change of angle, but you are on the right path comparing percent change, it is often more telling then raw numbers.

 

[LD1]

Mathematically your first statement that both lost 50% is not accurate, making your second statement very accurate. The nature of the trigonometry involved here is not linear and requires more math than comparing the percent change of angle, but you are on the right path comparing percent change, it is often more telling then raw numbers.

Splitting hairs at those angles.

Sin 30 = 0.5
sin 15 = .259
sin 7.5 = .131

Going from 30 to 15 .....you loose 48.2% of force. Going from 15 to 7.5, you loose 49.5 %

 

[davedj1]

Thanks for th e feedback. I had a very long day and can't wrap my head around this at the moment. I did look at a new 2501 I think it was Kubota today, the lift cylinders measured just a hair over 2" on the outside with the shaft measuring a hair over 1". That loader is only rated for like 800 lbs and the angle is fairly flat for the lift cylinders.

 

[npalen]

Anyone reading this thread will never look at a front end loader the same.:confused2:

 

[gladehound]

Thanks for th e feedback. I had a very long day and can't wrap my head around this at the moment. I did look at a new 2501 I think it was Kubota today, the lift cylinders measured just a hair over 2" on the outside with the shaft measuring a hair over 1". That loader is only rated for like 800 lbs and the angle is fairly flat for the lift cylinders.

I guess that's another way to go... just find a loader on a factory machine that does what you want and copy the geometry and cylinders. But then you still have to know your pressure. System pressure on that 2501 is around ~2,200 psi. If your system has and is designed for lower pressure, you may need bigger cylinders to do the same thing.

 

[gladehound]

If anyone wants another fun problem to work on... my KL402 loader on my Kioti DS4510HS has a roll back spec of 2990 pounds at 19.5" past the pin. I believe this is a mistake in the literature. This is about what my math works out to for one cylinder if you subtract a little for the bucket.

Here is some information to figure out the problem of how much roll back there actually is at a given point past the pins...

Bucket cylinder bore 2.16"
Bucket cylinder length 20.67"
loader relief pressure 2556 psi
Rod diameter 1.18"
Range of travel over full cylinder stroke 115 degrees
Number of cylinders = 2

The retract force of the cylinders combined should be 13,135 pounds (surface area cylinder ID minus surface area of rod multiplied by psi). Given cylinder length and degrees of travel it should have 136,166 inch pounds of torque, average, realizing that it wont be the same throughout range of travel based on geometry. At 19.5" getting 6,983 pound of roll back force average. Not even close to the 2990 pound spec at 19.5" at ground level.

The loader has an extra linkage like most modern loaders do and that makes the geometry a little more complicated. I realize that at ground level the loader curl is in the upper part of the range and therefore will be a little weaker. But going from ~7000 average (not peak) to ~3000 seems too extreme a difference.

This has me perplexed. I actually do have an 1,100 pound hanging scale coming in the mail next week. So I can weigh enough heavy stuff to actually do a real world test with measured weights.

But if anyone wants to take a crack at the math and tell me what I'm missing, I'm all ears.

 

[4570Man]

I think the extra linkage hurts you a lot at the upper end of the stroke. The rating is likely at the weakest part.

 

[npalen]

If anyone wants another fun problem to work on... my KL402 loader on my Kioti DS4510HS has a roll back spec of 2990 pounds at 19.5" past the pin. I believe this is a mistake in the literature. This is about what my math works out to for one cylinder if you subtract a little for the bucket.

Here is some information to figure out the problem of how much roll back there actually is at a given point past the pins...

Bucket cylinder bore 2.16"
Bucket cylinder length 20.67"
loader relief pressure 2556 psi
Rod diameter 1.18"
Range of travel over full cylinder stroke 115 degrees
Number of cylinders = 2

The retract force of the cylinders combined should be 13,135 pounds (surface area cylinder ID minus surface area of rod multiplied by psi). Given cylinder length and degrees of travel it should have 136,166 inch pounds of torque, average, realizing that it wont be the same throughout range of travel based on geometry. At 19.5" getting 6,983 pound of roll back force average. Not even close to the 2990 pound spec at 19.5" at ground level.

The loader has an extra linkage like most modern loaders do and that makes the geometry a little more complicated. I realize that at ground level the loader curl is in the upper part of the range and therefore will be a little weaker. But going from ~7000 average (not peak) to ~3000 seems too extreme a difference.

This has me perplexed. I actually do have an 1,100 pound hanging scale coming in the mail next week. So I can weigh enough heavy stuff to actually do a real world test with measured weights.

But if anyone wants to take a crack at the math and tell me what I'm missing, I'm all ears.

Can you show us the geometry of the compound linkage between bucket and cylinders? I would have thought that this linkage would tend to maintain a more consistent lever arm advantage thru the full motion. Is there another reason for the compound linkage?
We used that type of linkage extensively in farm tillage equipment design for folding wing sections to near 180 degrees.

 

[LD1]

If anyone wants another fun problem to work on... my KL402 loader on my Kioti DS4510HS has a roll back spec of 2990 pounds at 19.5" past the pin. I believe this is a mistake in the literature. This is about what my math works out to for one cylinder if you subtract a little for the bucket.

Here is some information to figure out the problem of how much roll back there actually is at a given point past the pins...

Bucket cylinder bore 2.16"
Bucket cylinder length 20.67"
loader relief pressure 2556 psi
Rod diameter 1.18"
Range of travel over full cylinder stroke 115 degrees
Number of cylinders = 2

The retract force of the cylinders combined should be 13,135 pounds (surface area cylinder ID minus surface area of rod multiplied by psi). Given cylinder length and degrees of travel it should have 136,166 inch pounds of torque, average, realizing that it wont be the same throughout range of travel based on geometry. At 19.5" getting 6,983 pound of roll back force average. Not even close to the 2990 pound spec at 19.5" at ground level.

The loader has an extra linkage like most modern loaders do and that makes the geometry a little more complicated. I realize that at ground level the loader curl is in the upper part of the range and therefore will be a little weaker. But going from ~7000 average (not peak) to ~3000 seems too extreme a difference.

This has me perplexed. I actually do have an 1,100 pound hanging scale coming in the mail next week. So I can weigh enough heavy stuff to actually do a real world test with measured weights.

But if anyone wants to take a crack at the math and tell me what I'm missing, I'm all ears.

As someone else said, that ~3000 is probably the minimum.

As to your extremely high number.....where did you get the 115 degrees from. I think that is a bit on the low side.

My LA844 loader has the same size cylinders. And they list 3 rollback measurements. 4400# at ground level, 4300# at 1500mm and 2800# at max height.

Not sure why that correlate the rollback with a lift height. I assume at each height, it is measured with the bucket bottom flat. So at the 3 different points, the bucket cylinders/linkages are extended more and more as the loader is raised.

Kubota also has a chart in the manual illustrating the curve. Fully dumped bucket is gonna be the weakest on rollback. The more it rolls back, the stronger it gets.....to a point. Then will start to get weaker again before being curled all the way. The strongest point is somewhere around bucket level on the ground. What is the distance between the bucket pins. (pin in loader arm to pin in 4-bar linkage that attaches to bucket.)