Welded some hooks on my FEL

kevinro · Nov 17, 2002

My $0.02: Take extreme care with your hooks. Your test of lifting the tree doesn't cut it.

There are several things to consider here. There are static and dynamic loads. Just because you can lift the tree doesn't really clear you to say that this hook is strong. Lifting the 500 pounds is only part of the story. As you start to move your 500 pound tree, it gains energy. Depending on how fast you are travelling, it can gain a suprising amount of energy. The basic formula is

F = 1/2 * M * V^2

The important thing to see is the v^2, which means as the speed increases, the energy goes up as the square of the speed. Bottom line is the forces involved get really big in a hurry. When you get that energy created by moving the object, it will eventually need to be disapated.

The true killer is starting and especially stopping. This is where the forces involved are at their maximum. The sum of the forces become the 'weight' of the object (500lbs) PLUS the mass of the object times its acceleration. Just as an example, say you go from a walking speed (4mph) to a stop in 1 second. The chain will see nearly 100 pounds of additional force. (F = m * a, F = 15.6 * 5.8ft/s. The mass of a 500 pound thing is 15.6 slugs. F= 90.625lbs) Thats a 20% increase doing a fairly common and seemly minor change of safely stopping. If you did a sudden stop, you could easily see an additional 500 pounds, which is a 100% increase. If it bounces, the forces can easily double that!

I would like to modify Hydraman's statement: If you are lifting 1000lbs, build it for at least 4000lbs.

gordon · Nov 17, 2002

<blockquote>In reply to:<hr>

My $0.02: Take extreme care with your hooks. Your test of lifting the tree doesn't cut it.

<hr></blockquote>

Ditto that, I've got no idea as to the math but I can say that using a repair link is only for one thing---chain repair. Your asking for trouble and the trouble will appear when your not expecting it.

Not saying this to put you down. You did a fine looking job on the install. If it were me I'd have regular hooks on there. Or better yet leave those and add a regular chain hook on the exact center of your bucket. First weld some angle to the top of the bucket to square it out so you don't end up bending it. Best of both worlds, a safe hook to work with and more welding time./w3tcompact/icons/smile.gif

You have to remember that in your tree test you were only picking up one end of the tree, not it's entire weight.

Please be safe hate to see you get hurt. Ive got pics posted on here somewhere of my hook install to my kubota bucket. Here it is I hunted it down.

Gordon

Hydraman · Nov 17, 2002

My experience (not a guess!!!) is that things WILL fly somewhere!! One time I was doing something that I should not have been, and when the broken piece of chain stopped-- it was inside the differential of my pickup!!!! Just very glad it went low!!! It penetrated the cover like an AP round!! Pickup would NEVER have done this with a steady pull; but , add sudden start or stop and things happen----SUDDENLY!!!!! Don

MikePA · Nov 17, 2002

I thought about using traditional hooks, but these caught my eye.
Hi Danny, other than 'catching your eye', was there any other reason that made you pick these hooks? Just curious.

Bud · Nov 17, 2002

Mike
Those pieces he welded on his bucket in the place of hooks are not hooks. They are made to repair broken chains, and are made to bend once they are placed in a chain. They have to bend to close to make the repair link. Once in a chain they will stretch under a load, and are not as strong as the chain.
Bud

JohnMiller3 · Nov 17, 2002

...these caught my eye...

How does your eye feel now...? /w3tcompact/icons/tongue.gif.../w3tcompact/icons/eyes.gif

MikePA · Nov 17, 2002

Those pieces he welded on his bucket in the place of hooks are not hooks.
Understood. I was curious why Danny chose them instead of hooks. Again, just curious what the thought process was.

Elkoboy · Nov 17, 2002

<blockquote>In reply to:<hr>

If you did a sudden stop, you could easily see an additional 500 pounds, which is a 100% increase. If it bounces, the forces can easily double that!

I would like to modify Hydraman's statement: If you are lifting 1000lbs, build it for at least 4000lbs.

<hr></blockquote>

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?

The massive forces you're talking about here could potentially overstress the loader itself, so instead of the chain or the hooks breaking, aren't you running the risk of something else on the loader itself failing?

I would think you would rather the chain, or the hook fail, rather than the loader arms, for instance, when you exceeded allowable limits, wouldn't you?

Or are the parts of the loader so overbuilt that this isn't a concern?

MikePA · Nov 17, 2002

I would imagine the relief valve would open if you tried to lift more than the loader was capable of long before the loader arms would give way.

Bud · Nov 17, 2002

Elkoboy
I don't think a small tractor would have enough power to bend the loader arms. When the chain was wrapped over the top of edge of the bucket it made resistiace to take some of the load from the connecting links. Those connecting links are not any good for what they were intended let alone to be used with one end open as a hook. Why do you think hooks are so heavy? They always have one end open. That's one hell of a strain.
Bud

Elkoboy · Nov 17, 2002

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 · Nov 17, 2002

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 · Nov 17, 2002

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 · Nov 17, 2002

The relief valve only comes into play when the lever is in the lift or lower position...
True.

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

kevinro · Nov 17, 2002

<blockquote>In reply to:<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 · Nov 17, 2002

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 · Nov 17, 2002

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 · Nov 18, 2002

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 · Nov 18, 2002

How about something like these??

Loges1 · Nov 18, 2002

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.