I don't get leverage

[jimmysisson]

Don't know if this is Hydraulics or not:
Just looking at Joe's NH55 loader pix. It illustrates something I don't get. Now that loader looks plenty stout, and it's on a tractor somewhat bigger than mine (Ford 2120). But the lower end of the lift cylinders is real close vertically to the loader arm pivots. In other words, the lift cylinders mount rather high up on the vertical loader frame towers. Mine mount near the bottom.
Sense tells me the farther they were mounted from the arm pivots the more lift power they'd provide, though more slowly, cylinder diameters being equal. My 7109 loader there's 26" between the arm pivots and the lower lift cylinder pins, there's 7' between the loader arm pivots and the bucket pins, and it's 44" from the upper loader arm pivots to where the lift cylinders pin on to the arms. My spec is 1800 # lift and 2950# breakout, at the pins, I think.
Joe's loader looks longer than mine to the bucket pins (is it a supersteer?). Maybe the cylinders are bigger? Mine are 2". His must be bigger dia. to get the same lift force, or I'm missing something? The 270TL loader (I think that's what Joe has) has about 2500# lift and 5000# breakout, substantially more. I've seen lots of Kubotas, etc. with the cylinders looking quite horizontal like Joe's. It's just physics, right?

 

[diyDave]

I'm sure this is a question for the engineers among us. Just from my mind's eye, the cyl's are mounted nearly the same, it's the curved shape of the newer loader that may be throwing the analysis. Someone with more computer skills than I probably could analyze where the pins are in a 3 dimensional position, and tell which is strongest. I place my bets on the curved shape, although it could be that the curved shape of the new design is 3 cents cheaper to produce, or a percentage point safer, on the lawsuit side, one never knows in today's sue happy society! (I would have said letigeous but according to my mac, I don't know how to spell it! )

 

[RobS]

Interesting observation. I'd have to run the math but the variables are the geometry of the loader (the loader is a "four bar linkage" with the bars being the distance from the lower cylinder pivot to the arm pivot, arm pivot to upper cylinder pivot and the cylinder acts as two links), cylinder diameter, hydraulic pressure and the leveraged arm of the loader (from upper cylinder pivot to load center). It is likely that many, if not all, of those variable differ between the two machines.

 

[6sunset6]

I had a 7308 loader Str arms , now I have a 240 curved arms both NH. I believe the cylinders were the same size. The relief valves were close . The 7308 was on a 20hp and the 240 is on a 34hp but I don't think that makes any difference. What I know is I can lift more with the 240 curved arms than I could with the 7308. This is with forks and pallets of firewood.