Welded some hooks on my FEL

[Elkoboy]

Here's an example of the forces I'm thinking of (and of which Kevin refers to in his post):

You lift the 500 lb. object with a chain and hook, attached to the loader which can lift 500 lbs. You then proceed to drive your tractor with that load, and drive into a shallow hole (or otherwise hit a bump) as you go. The dynamic forces you would place on the chain, hook, your front axle, the loader, and other parts of the tractor would exceed that static 500 lbs, depending on how fast you were going, how deep the hole was, etc.

And wouldn't you rather the chain or hook break when those excessive forces hit, or would you rather risk stressing or breaking the loader, the front axle, or some other part of the tractor that would absorb those forces?

What's the established logic on this?

Does the relief valve come into play here at all?

 

[Hydraman]

If you can tie the irresisable force to the immovable object with out breaking something --so what!!! If the rear wheels of the tractor come off the ground before something breaks; you have it strong enough. If something breaks before the rears come off the ground......you got problems.. somehow, sometime, somewhere, somebody's gonna get hurt!!! Hope it is not someones little one standing nearby, just watching!!
When the rears start to come up---I guarantee that most people WILL set the load back down, and either lighten the load, or regroup, in some way!!! Thereby lowering the risk factor!!! The loader should always be stronger than the tractor!! Bye now. Don

 

[Hydraman]

The relief valve only comes into play when the lever is in the lift or lower position... It has nothing to do with holding the static load!!

 

[MikePA]

<font color=blue>The relief valve only comes into play when the lever is in the lift or lower position...</font color=blue>
True.

<font color=blue>It has nothing to do with holding the static load!! </font color=blue>
If you can't get the load off the ground, because the relief valve opened, there wont be any static load to hold.

 

[kevinro]

<blockquote><font size=1>In reply to:</font><hr>

Just out of curiousity, why would you want to overbuild at one point, moving the possible point of failure (the weakest link) to another part of the tractor, like the loader arms for instance?

<hr></blockquote>



Great point. When you design something, especially a modification to someone elses design, how it affects the rest of the system is something to consider. A system is only as strong as its weakest point.

The loader has a weak point. That weak point is more than likely the hydraulic piston, and is the weak point by design. By not allowing the end user to exert more force than the arm can handle, the issue of over stressing the loader is mostly removed. Therefore, it makes sense to keep the force producing element of this system as the weakest point.

Part of designing products is doing something called a failure mode analysis. It basically means: What if the user does something to overstress the unit. What happens? What can be done to make it safer? Though I don't design tractor parts, if I did, the obvious thing to do in failure mode analysis is to limit the amount of power and insure the rest of the system can withstand whatever can be put into the system.

Adding a weaker component, such as the chain hook, is a poor idea because you are prone to failure. Adding a stronger element, such as a real chain hook, would be a safer thing to do since the failure mode of the piston is to not move. The failure mode of the chain hook is to drop something, or potentially send bits of metal flying.

Kevin

 

[mrcaptainbob]

I absolutely agree 100%. Besides the 'heft' there's also the difference in type of steel used. As I mentioned before with the vise-grip test...if you can bend it by hand then how would it be expected to hold a load heavier than that? Try twisting even a low grade chain hook with vise-grips.....Mild steel is just a not a good choice to use in stretching/twisting situations.

 

[Hydraman]

Even the old 'low pressure' hydraulic systems of yesteryear had no problem lifting more than the weight of the tractor was able to hold with out opening the relief valve; thereby picking the rear wheels off the ground. This was with small farm tractors such as the JD model A and the Farmall H and M; which are a lot heavier than the CUT's of today, which use hydraulic pressure of 2000 PSI or more.
The loader arms of the old 'Farmhand F-11' loaders were a weak point,and many of them have been reinforced and welded on big time. Second thought--the whole F-11 was weak.
But why does anyone want to have a nice machine-- then get chincy with a couple of chain hooks is beyond me. Make it strong enough that there are no problems. Don

 

[bgott]

Anybody give a thought to designing a set of fold -down hooks? I've got a design floating around in my head, now I just have to put it on paper. I use my loader on a lot of stuff that would get wrapped up in regular hooks and give me a pain when it's time to dump. I throw stuff up on the loader arms, like old mattresses, that gets hung up on the bucket level indicator so I'm sure anything protruding lower down than the loader arms is a sure recipe for disaster.

 

[gmason]

How about something like these??

 

[Loges1]

If you hook to just one hook on the outer end of the bucket like that bad things can happen to your loader way before a chain breaks. Bent arms and/or bent cylinders are a possibility. One hook in the middle or a hook where each arm attaches to the bucket would probably work better. Still I have heard about bent cylinders just from over loading. Just my .02 worth.