3pt vs fel lift

[kossetx]

Help me understand this. I know a 3pt can lift more than a fel, but...

My tc 40 a has abou (all weight rounded off) 2300# of lift 24" behing th balls to a total height of about 24". My 17 la lifts @20" forward of the pins the following, 1400# at full height (98" at level bucket), and 2100# at 59".

If I brought the 59" down to 28" (700+#)and sutracted for the added 4" in length for the 3pt measurment, wouldn't that make the fel have roughly the same lift capacity than the 3pt? I didn't do the math, I'm just reasoning.

Whatcha think?

 

[Bob_Skurka]

I thought I would know this answer. But I don't have a clue!

However, you should be able to find the answer. Many loaders have a graph that shows how much capacity they have at various points. Using the graph (which is probably in your FEL's owners manual) you should be able to pick any lift height and graphically determine the capacity at that height. Generally speaking a FEL has a lot more capacity lower to the ground that it does higher in the air (due to the geometry of the loader), while there is no practical difference in the capacity of a 3pt lift as it cycles.

 

[schmism]

Generally speaking a FEL has a lot more capacity lower to the ground that it does higher in the air (due to the geometry of the loader),

i know its the exact oppisite for my FEL due to geometry.

when at ground level the cylinders push almost horzontally.

when fully raised they are amost vertical.

we could bust out the free body diagram if you wish

 

[daTeacha]

Do we really wanna go there? You'll need to include all the angles and changing theoretical lever arm lengths, too If you do bring them up, how about including some stuff about attaching at different points on the loader arms and increasing your maximum lift that way?

My Case (NH) loader bucket is very far out in front of the tractor throughout its cycle, probably a foot or more farther than a non-factory loader. If I put a chain about where the parking leg is connected to the arms I could lift more weight than with the ends of the arms, but what good would it do unless I had a big rock to move or something like that?

Then there's the weight of the bucket itself. Mine is 285 lb, I think and the grapple adds another 150 to that. If I'm just after maximum weight lifting ability, I should take the bucket off and just hook a chain to the ends of the arms.

And lets not forget that putting a boom on the 3 point will not let you lift as much at boom end as nearer the tractor.

 

[jinman]

Whatcha think?

I think my hydraulic toplink on my 3PH is like the curl cylinders on my bucket, but with a lot less breakout force than the FEL.

Actually, I think you might be right on the other numbers, but since you know the basic numbers, what is the reason for the critical calculation? Since there is only one hydraulic pump, the pressure is exactly equal at either end. Both ends have the capability of being in such different positions that you really can't make more than the most general comparison in my opinion.

 

[kossetx]

Bob, Thanks!

Schmism, My numbers came from NH. I don't understand how your NH could be the opposite.

Dateacher, I have no idea what you are talking about. I was simply using NH numbers, not adding anything, and yes, I did want to go there.

Jim, Well, The purpose is I'm trying to decide to build a tool and whether to build it for front or rear mount. I was also always under the impression that the rear lift was much stronger than the front lift is. When I looked at the numbers, it just didn't seem to be that way. I'm not an mechanical engineer. I am simply using reason and I wondewred if anyone else saw what I saw in these numbers. General comparison was the intent though.

 

[Bob_Skurka]

i know its the exact oppisite for my FEL due to geometry.

when at ground level the cylinders push almost horzontally.

when fully raised they are amost vertical.

we could bust out the free body diagram if you wish

I'm pretty sure you misunderstand the loader capacities. Pull up a manual for any brand that shows capacity at multiple measurement points.

• Some show only the capacity at "Maximum Lift Height."
• Some show capacity at "Maximum Lift Height" and also at "59" above ground."
• Still others show capacity at "Maximum Lift Height," and at "59" above ground" and also at "12" above ground."

You will clearly see that capacity at "Maximum Lift Height" is the lower than the capacity at "59" above ground" and that is similarly lower than the capacity at "12" above ground." In fact, at least one manufacturer now is not showing the capacity of their loaders at the maximum lift point in their marketing materials. They now are showing the "59 inch" capacity on their marketing materials, I suspect because it makes their loaders look stronger. An unsuspecting and uninformed tractor buyer will probably presume that their loader is stronger than it really is.

 

[Soundguy]

Some loader valves also employ a second relief valve that is set lower than the main system relief. I've seent hat many times... thus meaning the 3pt could get more pressure than the loader.. etc...

soundguy

 

[daTeacha]

Unless I'm totally misunderstanding the way hydraulics work, the maximum force a hydraulic cylinder can exert is a function of two things -- the pressure from the pump and the surface area it pushes on. If your 3 point cylinders are not the same diameter as your FEL cylinders, you will get a different amount of push on the levers making up the rest of the mechanism. If someone doesn't do their homework carefully, there is little chance that the two will lift the same amount. A manufacturer can decide how much each end of the tractor can/should lift safely and build it to suit.

So what are you trying to build? Is it something that would be handier to use on one end of the tractor over the other? We got off topic somewhat and this thread hasn't been much help with what you're trying to do. If it's something like a post driver, I'd be looking at the front end just because it would be easier to position accurately.

 

[Bob_Skurka]

Rich, in addition to what you wrote, there is also the issue of mechanical advantage that can be added to your list. Realize that HOW and WHERE the hydraulic cylinders are attached to any given thing will also affect capacity. Think in terms of a child's see-saw on a playground. Two equal weights and the see-saw is level. However if you lengthen one side you gain mechanical advantage and that side now requires less weight to hold up a heavier weight on the opposite, shorter side. So there is some margin that must be factored in for the engineers who design the systems because they will typically utilize mechanical advantage when they are able.