lift capacity vs. breakout force

[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