Lift Capacity @ 24" for SubCompacts

[LD1]

I have tried explaining it everyway I can with the given examples. I guess the only way to really solve this is to have someone with a carryall hook it up to their tractor with the toplink in the highest position, ballast the front, and start stacking on blocks or whatever for weight until the 3PH can no longer lift the load. And then, do nothing else but change the toplink to the lowest position and see how much weight has to be removed until the 3PH can lift the load again.

Or if someone has a spring scale or load block or whatever to anchor to the ground and hook to the back of an implement like a blade of bushhog and see what the lift force is at carious toplink positions.

If I had a 1k spring scale, I would hook up my bushhog and chain the tail wheel to something it wont lift, and see what the max force is at the top position vs the bottom.

Any volunteers have a large enough spring scale be willing to give this a shot??????

 

[arrabil]

It adds to the load because it is a physical connection point in which makes the lift arm NOT lift the load straight. The toplink is FORCING the implement to rotate about the lower pins, thus causing the tail wheel of a bushhog for example, to be lifted proportionally higher than the lower links. Thus a proportionally lower rating. It will require more force the higher the tailwheel is lifted in relation to the lower arms. Which is exactally what changing the toplink position does.

So the toplink does not add load. You have to agree with that then. The toplink REPOSITIONS the load, possibly changing the center of gravity of the object, which could affect the lift capacity of the rockshaft. But in no way EVER does the toplink ADD load. Right?

And then, do nothing else but change the toplink to the lowest position and see how much weight has to be removed until the 3PH can lift the load again.

The lower 3pt mount is the fulcrum against which the rockshaft lifts the object. Until the toplink becomes a fulcum, at horizontal or higher, it has no effect on the lift capacity (as long as the object can rotate). So at the exact moment when the rockshaft fails to lift an object, you can switch the toplink position and the rockshaft will still not lift that object.

 

[LD1]

It can be worded anyway you like. But the toplink position DOES affect the lift capacity at points BEHIND the lower arm pins.

Wether you cal it lifting, rotating, or what, force is required to do the work.

If you would like, I can word it this way, the toplink causes the implement to rotate, which requires a given force . If the toplink is lowered, it causes the load to rotate MORE, which requires MORE than force than trying to rotate the load less if the toplink were in the top most position.

either way, the 3PH cannot "CREATE" work. It can alter and change the forces applied to it. You are trying to say that it doesn't take anymore force to raise the implement higher (toplink in lower position), which is absolutly false.

 

[tsteahr]

Explain how this is possible. How can the toplink add to the load being lifted outside its own mass?.

A non parallel top link adds or subtracts (changes) to the load lifted through the vector decomposition described numerous times above. I think it's clear you have not grasped this. This is at the core of your not understanding this issue. I am out of ideas how to convey this to you and I suspect LD1 is running out of ideas as well.

I was responding to what you brought up. Post #37 since you have no memory of it.

I remember it. When I said "Imagine yourself standing on the implement holding on to the top pin." I was trying to create a visual, conceptual aid. Not a literal example. Sorry you misunderstood this.

That cannot be true as in the same exact situation you are saying the link is compression while LD1 is saying its in tension. In fact you have compression and tension reversed in every one of your examples.

I have never said the top link is in compression. I have always referred to tension in the top link.

LD1 and I are not arguing. I don't see why you are being argumentative with this subject. There is nothing to argue. We have tried (and failed) to teach you how this linkage system works. The forces throughout a linkage system are clearly defined by basic engineering principles. If you don't understand those principles I can't help. I'm not going to spend the time or effort to try and teach you when I believe your mind has been made and is closed to learning this subject. You could find another engineer and shop for a answer you like better.

 

[tsteahr]

So the toplink does not add load. You have to agree with that then. The toplink REPOSITIONS the load, possibly changing the center of gravity of the object, which could affect the lift capacity of the rockshaft. But in no way EVER does the toplink ADD load. Right?.

The toplink transfers load. The position of the toplink impacts the mechanical advantage (leverage) of the linkage system. The toplink changes the load distribution within the linkage system. You are correct that the toplink does not Add load in the sense it does not make a 350lb cutter magically weigh 400lbs.

The lower 3pt mount is the fulcrum against which the rockshaft lifts the object. Until the toplink becomes a fulcum, at horizontal or higher, it has no effect on the lift capacity (as long as the object can rotate). So at the exact moment when the rockshaft fails to lift an object, you can switch the toplink position and the rockshaft will still not lift that object.

These sentences make no sense.

Incorrect At the exact moment the linkage system can no longer lift the object, if you raise the connection point B the load can now be lifted. You have increased the mechanical advantage of the linkage system.

 

[rjkobbeman]

The length and/or position of the toplink changes the leverage the implement has against the lower arms. The more leverage the implement has, the greater force exerted on the arms. The more force exerted on the arms, the less weight can be lifted.

How far the weight is behind the lift arms is also part of the equation.

Another way to think about it is looking at my FEL. My FEL has two different attachment points for my boom cylinders. One is for max height and one is for max lift capacity. Moving the lift points changes the leverage.

The force against my hydraulic system is more when my cylinders are in the max height position than when they are in the max lift capacity position with the same weight in the bucket.

 

[arrabil]

It can be worded anyway you like. But the toplink position DOES affect the lift capacity at points BEHIND the lower arm pins.

Oh come on. You said the toplink adds force three times and then said the 3ph can't create work and yet you think the problem is me being picky with the wording? Clearly you have the right words here, but I can't believe you think both of your previous statements mean the same thing to anybody.

You are trying to say that it doesn't take anymore force to raise the implement higher (toplink in lower position), which is absolutly false.

I did not say that. I said the lift capacity of the rockshaft, ie where it won't raise the object off the ground, is not affected by the position of the toplink. I do agree with you that an object that rotates, and significantly changes its center of gravity from this rotation, is affected by the toplink. Obviously. BUT, not because the toplink acts on the lift capacity. The toplink acts on the distance the CoG is from the ball eyes which in turn affects the lift capacity. The toplink fundamentally changes the geometry of the lift (by moving the CoG to 25" for example), not the lift capacity @ 24".

 

[tsteahr]

Oh come on. You said the toplink adds force three times and then said the 3ph can't create work and yet you think the problem is me being picky with the wording? Clearly you have the right words here, but I can't believe you think both of your previous statements mean the same thing to anybody.


I did not say that. I said the lift capacity of the rockshaft, ie where it won't raise the object off the ground, is not affected by the position of the toplink. I do agree with you that an object that rotates, and significantly changes its center of gravity from this rotation, is affected by the toplink. Obviously. BUT, not because the toplink acts on the lift capacity. The toplink acts on the distance the CoG is from the ball eyes which in turn affects the lift capacity. The toplink fundamentally changes the geometry of the lift (by moving the CoG to 25" for example), not the lift capacity @ 24".

This is false. If you lift the toplink from B' to B AND shorten the toplink such that the position of A is unchanged (The CoG remains unchanged) the lift capacity has improved. Because the mechanical advantage of the linkage system has been improved. The tradeoff is that the linkage system will not be able to lift the load as high.

 

[LD1]

Oh come on. You said the toplink adds force three times and then said the 3ph can't create work and yet you think the problem is me being picky with the wording? I am trying to do you and everyone else willing to learn a favor by trying to simplify things in laymans terms. Exuces me if my "dumbed down version" is not politically correct.
Clearly you have the right words here, but I can't believe you think both of your previous statements mean the same thing to anybody.
It seems everyone else is understanding except you. Again, I am trying to come up with different ways to explain/describe the same thing hoping one of them may get through. But I too am out of Ideas.
I did not say that. I said the lift capacity of the rockshaft, ie where it won't raise the object off the ground, is not affected by the position of the toplink.Sure I could agree with you here that if you are trying to lift something that is just TOO heavy to even get off the ground for the toplink not to matter. But again, why would someone be trying to lift a 1000lb 8' bushhog with a subcompact?? I do agree with you that an object that rotates, and significantly changes its center of gravity from this rotation, is affected by the toplink. Obviously. BUT, not because the toplink acts on the lift capacity. The toplink acts on the distance the CoG is from the ball eyes which in turn affects the lift capacity. The toplink fundamentally changes the geometry of the lift (by moving the CoG to 25" for example), not the lift capacity @ 24".

I'll actually try one more way to get the point across here. Imagine if you could lower the toplink low enough where it were at the same height as the lower arms connect to the tractor. (in the examples above, points A and C on the tractor being on the same plane.)

This would make any implement rotate on the same angle as the lower arm. Completely getting rid of the //ogram linkage. this would make any implement on the 3PH act exactally like a lever. If the loer arm is level, the implement will be level, if the lower arm is @ a 30* angle, so is the implement. Again, Just a basic lever. If you can picture this, would you now agree that the farther back you go, the capacity is reduced proportionally????

 

[arrabil]

1) WELD a 550lb object to the lower hitch arms. Put it's CoG 24" behind the ball eyes.

2) WELD an 1191lb object to the lower hitch arms. Put it's CoG even with the ball eyes.

Do NOT attach the toplink for either.

Tell me, will the MF GC2400 lift these loads to its maximum rockshaft height?