lift capacity vs. breakout force

[Eagleview]

No mate , it's 8.00am Friday morning . This is the best time to have a yarn . You guy's are finished for the day and i'm just starting .

 

[IslandTractor]

No mate , it's 8.00am Friday morning . This is the best time to have a yarn . You guy's are finished for the day and i'm just starting .

I was way off. I thought there was about a 11-12 hour time difference to the US East Coast. Have a good day.

 

[IslandTractor]

No mate , it's 8.00am Friday morning . This is the best time to have a yarn . You guy's are finished for the day and i'm just starting .

I was way off. I thought there was about a 11-12 hour time difference to the US East Coast. Have a good day mate.

 

[Eagleview]

My mobile phone tells me it is now 8.19PM in New York and it is 11.19AM here in NSW Australia .

 

[Farmerford]

Iron Horse:

Nice machine. What is the lift capacity of your excavator with he stick pulled bacK to vertical? Do you dig around the trees first, or do you just pull them out without digging?

 

[Eagleview]

No digging of trees this size . It would be too time consuming to keep removing the grab and fit a ripper or bucket . It has a lift capacity of 11,000 kilograms (about 12 tons) but does not rely on this function when extracting . It is a combination of all functions to pluck a tree out . Mostly i pull the dipper arm in while rolling the grab back . This tilts the tree towards me and breaks the roots . I keep on pulling with the arm which drags the tree through the soil 8" or so (the top ram pushing on the short arm extension does this) , then i lift which pulls it out of the hole . I bang it up and down a few times to get the soil off of the roots and back into the hole . I then use the root system like a big paint brush to smudge the soil and grass surrounding the hole which covers it over . 3 weeks later the grass has grown back and you cannot see where the tree was .

On edit .
The tree in the picture was a little stubourn , i had to grab it a bit higher for leverage and push it away first to loosen before doing the above proceedure . Also this particular tree had a branch that looked like it would break off if i banged it up and down and land on my cab so i did'nt , that is the reason there is soil still on the root ball .

I did'nt know i could click on the photo to enlarge it , i just did and i can nearly read my phone number on the boom .

 

[Window Geek]

I believe that they build or order a certain bucket, and then figure the cylinder size that will give a reasonable breakout before the bucket is destroyed. (SNIP) A shorter bucket on the same frame, will have a greater break out force, due to mechanical advantage. The same thing applies to the lift cylinders also. You could go to a larger cylinder, but you might place your front axles at risk, by overload. Just enough is what they settle on.

You're right there, JJ. The breakout is usually higher than lift capacity. You can use that to your "advantage" for lifting things heavier than your lift capacity. When trying to unload my log splitter and PHD off the pickup truck at the same time, I learned that Kubota folks knew about guys like me and set the pressure relief to keep me from bending the loader.
BUT, with the breakout force at about 850 pounds, I was able to curl back on the bucket just enough to get the crates off the pickup and drive the truck out from underneath. Cool! This was during the first few days of owning my slightly used machine. (I bought it with less than 50 hours on it.)

Later when I tried to do a little grading, the left-hand edge of the bucket seemed to hit the driveway about a half inch before the right-hand edge.
I'm sure the first owner must have bent it!

We've all seen that bucket edge flex with fork attachments or picking up that slightly too big rock in the back yard. It's the breakout of the bucket, with its shorter, stronger mechanical advantage, that lets you get it off the ground. You can move it, but you'll never pick it up.

 

[Eagleview]

You're right there, JJ. Later when I tried to do a little grading, the left-hand edge of the bucket seemed to hit the driveway about a half inch before the right-hand edge.
I'm sure the first owner must have bent it!

Do the oposite to what you did to twist it . I'm allways twisting my loader , hitting unseen stumps etc . I just put the other corner against a stump , select low low and give it a push , sometimes while lifting . It will go back , it's not bent , only twisted .

 

[fitterski]

This may seem like a dumb question, but ....

There is no such thing, only answers can be stupid and Picasso discovered that much in spite of his handicaps when he said "Computers are useless, they only give us answers"

So I feel at ease jumping in here albeit a little late. My Cat-426 has a breakout force of around 6000 lbs against a max lift of maybe 4000. I always presumed that maximum lift was load lifting capacity before the rear goes airbone, and that breakout force was total bucket upward force limit that can be exploited when the bucket is higher and nosing over becomes mostly impossible. One ezample of this is when forcing with the bucket at a high angle against a wall of cooked stone (once blew a front tire doing this). I just can't see that single tilt cylinder pumping more than the dual bucket lift cylinders, superior geometry and all. Correct me if I'm wrong, it wouldn't be the first time.

I now have a more or less 12000-16000 lb 5 foot high retaining wall to lift 3 inches, the amount it has settled toeing-under in more than 20 years. The 50 ton chinese jack I bought isn't doing it because it's pushing the 16x16 inch square plate under it into the ground instead. This may improve as I ram more material under the plate but it may also prove to be limiting in the end.

So how does this tie into the topic? I plan to maybe borrow a big loader to try it with, I can get to the wall from above with the bucket lip easily right over the lift point approaching it on the high refill side of the wall. I'm thinking 2 chains with L shaped clips made from 1 inch plate. My 426's breakout of 6000 lbs is sure to be inadequate (from experience) but I'm curious as to what a bigger loader might be capable of.

 

[dadohead]

The breakout force is the amount the bucket can exert in it's crowd back function ie. tearing out a tree root while rolling the bucket back , as opposed to trying to lift it with the loaders lift arms (lift capacity).

Dead on... The bucket force is designed to overcome the crowd which can in-turn overpower the boom. That way the operator always has one more trick in his bag and doesn't get the bucket stuck.

 

[Oz_Kioti]

I'm trying to understand the figures here.

Breakout Force is quoted for the pivot pin. So does this assume that with the pivot pin stationary, the breakout force is that which is applied by the bucket cylinders?

And if so, by extrapolation, can one then calculate the breakout force at the lip of this particular bucket?

 

[LD1]

Well this thread came back from the dead after 12 years...lol

What applies to larger loaders may not apply to compact tractors.
For example, the SAE J732 that was quoted in post 17 says that the rear cannot be chained down and if the rear of the machine lifts off that ground you have arrived at your breakout force. And that if BOTH lift and Curl are used that the dominate pivot point must be specified.

Well they dont list a dominate pivot point. They simply list at pivot pin. The loader has several. And no tractor would come close to its rated capacities without tying the rear down or adding significant counterweight.

What does it all mean for compact tractors....simple.

Breakout force is simply what the loader can lift at or near the ground level.

Loaders geometry is such that the the higher you go, the angle of the cylinder in relation to where its pushing on the boom becomes more acute. And since in its basic form.....figuring out a cylinders force when mounted on an angle is the SIN of said angle....the higher you go, the hydraulics have LESS lifting capacity.

Some manufactures list capacity at both max height and at ground level (which is breakout force). Some offer a 3rd point of reference and list lift capacity at 1.5M (59") Which would be representative of unloading pallets off a flat bed.

Think of the loader lift capacity as a curve (cause it usually isnt exactly linear but close). In the above example of the kioti KL701 loader....at ground level the loader lifts with a force of 5359#. As soon as you start raising the capacity starts dropping. The higher you go the more it drops up until max height where its down to 3384#.

Which is why, if you are lifting something at or near capacity....you may find it will lift off the ground and get to a height of maybe 4' then stall out and wont lift any higher.

Some manufactures even give a graph representing this lift vs height curve I eluded to.

 

[fitterski]

I'm trying to understand the figures here.

Breakout Force is quoted for the pivot pin. So does this assume that with the pivot pin stationary, the breakout force is that which is applied by the bucket cylinders?

And if so, by extrapolation, can one then calculate the breakout force at the lip of this particular bucket?

View attachment 717781

I just looked at some more recent Cat specs and noticed a trend to cite breakout in terms of torque rather than force (i.e. ft-lbs). Still my 426's supposedly 50% above lift capacity breakout force means that, if I hit a bump in the road while transporting, my snow blower kept comfortably aloft will untilt the bucket holding it level as well. So I'm confused too, although only academically cause it isn't of any other interest in my case. I could in fact do more with math if Cat had quoted a torque value instead of a 6000 lbs force.

 

[LD1]

I just looked at some more recent Cat specs and noticed a trend to cite breakout in terms of torque rather than force (i.e. ft-lbs). Still my 426's supposedly 50% above lift capacity breakout force means that, if I hit a bump in the road while transporting, my snow blower kept comfortably aloft will untilt the bucket holding it level as well. So I'm confused too, although only academically cause it isn't of any other interest in my case. I could in fact do more with math if Cat had quoted a torque value instead of a 6000 lbs force.

Actually, if you look at the more recent specs...they are in lbf...which is NOT ft-lbs.

And if you care for an education in physics...lbf is technically the CORRECT way that it should be published. because lb is simply weight whereas lbf is a force (which also allows them to convert it to Newtons).

Think of it this way....a pound in space or a pound on the mood is NOT the same as on terra-firma.

Yet in a hypothetical scenerio....if the backhoe were on the moon it would still only be capable of the same force (lbf).

So for all intents and purposes....if you see lbf on a loader or backhoe spec sheet....it means the same as if it just said lb