load distribution on FEL chain hooks

[jimh406]

I’m not an engineer but this idea of a short chain as a bridle should be carefully re-evaluated, IMO.

Believe it or not, I carefully evaluated using chain with two attachment points vs a single hook.

Using two attachment points means that the chain has double the the strength except in the hook attachment point on the chain in the center. If that center link broke, it would be similar risk as having a center hook except the rest of the attachment would likely go straight down and the chains would fall down as well.

However, my tractor doesn’t have enough lifting force to break the chain that has a working limit of several times the lifting force. I think the chance of breaking the chain is neglible assuming you aren’t trying to use the smallest chain possible.

There are exactly two times the weld surfaces that a single hook would have. Half of the load is on left hook and half is on the right hook. That is an advantage of loading both hooks. If a single hook with welds could hold the load, then two hooks should certainly be able to. But, again, my tractor can’t lift enough to break the hooks off assuming my welds are good enough.

Finally, the hooks are also rated for several times my tractor lift capability. Also, half of the load is on each hook. So, the hooks may/may not be quite as strong pulling at an angle, but it’s unlikely they are going to break.

Fwiw, I’ve used it several times including yesterday, not even the paint on the hooks is damaged yet from lifting.

 

[Freeheeler]

Finally, the hooks are also rated for several times my tractor lift capability. Also, half of the load is on each hook. So, the hooks may/may not be quite as strong pulling at an angle, but it’s unlikely they are going to break.

That's the problem. With a 2 anchor system the load on each hook changes as the angles change. With a very long chain, the angle of the 2 sections of chain going to the hooks is small. As the chain shortens, the angle increases. With your set up as pictured, the angle is almost 180 degrees, that is, your chain is almost a straight line between the 2 hooks. At an angle approaching zero (very long chain) the force exerted on each hook is 0.5 times the load. At 90 degrees (long chain) the force is 0.7 x load. At 120 degrees, the F is 1.0 x load. At 170 degrees F is 5.7 x load. At 180 degrees which your set up is approaching, the force exerted on each hook is 57.2 x the load. In other words, if you try and lift a 100lb load, you will be exerting 5,270 lbs sideways on each hook. Those had better be some strong welds.

 

[jimh406]

In other words, if you try and lift a 100lb load, you will be exerting 5,270 lbs sideways on each hook. Those had better be some strong welds.

Please show how you are calculating your 5270 number.

 

[Freeheeler]

There are charts that have angles and Force values. At 179 degrees F = 57.2 x load. So the math is pretty simple. I'll try and find a chart that I can link to show you. I got those values off of a file I have for doing rescue rope work. I couldn't find a way to link just that one page and the whole file is 70 something pages long.

 

[Freeheeler]

I hope this helps.

 

[Freeheeler]

first fig F = .71
second at 120 degree F = 1.0
third fig at 180 F= infinity
from my initial source at 179 degrees F=57.2

 

[jimh406]

I don’t think it would be 5720, but in any case, I was able to find an actual chart for different angles. I’m not at 0 degrees, fwiw, but changing the angle would be fairly easy since I have other chain to use.

For those following along, if I was trying to reduce the minimum force on each leg, my angle is wrong. 45 degrees would be more appropriate. The information that I found says you shouldn’t go less than 30 degrees with a 2 leg sling because that’s when the force on each leg is the same as the center hook.

 

[GeoHorn]

Jim, I believe the statements you made in post 21 are incorrect…especially in paragraph 2.
I know you’ve heard the phrase: “A chain is only as strong as its’ weakest link.”.

I believe the stresses added to your bridle and the side-loading of the hooks is Adding stresses…not reducing them.

 

[jimh406]

I believe the stresses added to your bridle and the side-loading of the hooks is Adding stresses…not reducing them.

My post #27 says the affect of the angle. However, it’s clear that I’m putting no stress on the center of the bucket which was the primary goal.

Also in #27, I could change the angle to reduce the load on the hooks. You think it is necessary. I don’t think so.

Center loading the bucket with a hook also puts additional stresses on the loader/bucket.

 

[GeoHorn]

My post #27 says the affect of the angle. However, it’s clear that I’m putting no stress on the center of the bucket which was the primary goal.

Also in #27, I could change the angle to reduce the load on the hooks. You think it is necessary. I don’t think so.

Center loading the bucket with a hook also puts additional stresses on the loader/bucket.

It’s your machinery and you can do with it as you deem best… I’m not trying to do anything but help you.
I also offered a solution to strengthen your bucket. Kubota mostly produced “material handling” buckets (not construction-buckets) and they are fairly light-duty for tasks many of us contemplate…. but there’s a simple and rewarding solution: Beef up that upper bucket by welding a steel plate across it (which also provides a much sturdier base for hooks than that thin, lightweight upper surface Kubota continues to sell.)

 

[jimh406]

It’s your machinery and you can do with it as you deem best… I’m not trying to do anything but help you.
I also offered a solution to strengthen your bucket.

No worries. I read about the strengthen the bucket approach before building the bridle. As it is, I rarely lift anything attached to the bucket, and like I said, I “could” change the angle easily to change the bridle to reduce the loads on the hooks.

 

[Freeheeler]

I was just trying to help as well. Wanted to make sure you realized that you weren't cutting the hook stress in half like you stated, it was actually increasing the stress based on the pic you posted. Personally, I always make sure I'm at 120 degrees or less because that's the 1:1 ratio and I know that my hook stresses are equal to or less than the load I'm lifting. Adding just a few links would reduce the angle quite a bit and not affect your lifting height much at all, while still being well above the bottom lip of your bucket. Stay safe and happy lifting.

 

[GeoHorn]

Please forgive me when I repeat that using the chain in a bridle places side-loads on the hooks and can quickly overload the chain in a dangerous manner. The Peerless company mfr’s chain and they state:
PEERLESS INDUSTRIAL GROUP PRODUCTS ARE INTENDED TO BE USED AT OR BELOW THE MAXIMUM WORKING LOAD LIMITS SPECIFIED IN CONSTANTLY INCREASING FORCE APPLICATIONS UNDER DIRECT TENSION OR IN A STRAIGHT LINE PULL.

SHOCK LOADING IS PROHIBITED AND SIDE LOADING MUST BE AVOIDED, AS IT EXERTS ADDITIONAL DYNAMIC FORCES OR LOADING WHICH THE PRODUCT IS NOT DESIGNED TO ACCOMMODATE.

Here is an illustration of how stress is multiplied when using chain as a bridle.…Observe how the tension rapidly increases when applied at an angle instead of a straight-pull……. AND…. it can quickly become dangerous and when it breaks it can “whip” broken links as projectiles:

 

[jimh406]

it can quickly become dangerous and when it breaks it can “whip” broken links as projectiles:

What I’m doing is not identical to that picture. Also, I didn’t measure the angle, but the picture I posted is a top view.

In the graphic you posted, the chain tension shows less than double the load. Let’s say, it is even 3 times the load. That’s still below the working limit for the chain I’m using if I was at maximum lift capability. The reality is that I’m probably never going to get anywhere near maximum lift capability with the few items I’m lifting. It’s more likely it will only be a few hundred pounds at a time. Even my rear blade was only 400 lbs.

As noted, simply changing to using a longer chain eliminates the increased load. Meanwhile, a single attachment point is still putting extra stresses on the bucket no matter if you attempt to reinforce it or not. For sure, I won’t be bending my bucket in the middle. Again, the goal of the approach.

You say it’s up to me, but you keep posting. I guess you are mad that I didn’t immediately give up my approach. I hope you aren’t losing sleep over it.

 

[GeoHorn]

What I’m doing is not identical to that picture. Also, I didn’t measure the angle, but the picture I posted is a top view.

In the graphic you posted, the chain tension shows less than double the load. Let’s say, it is even 3 times the load. That’s still below the working limit for the chain I’m using if I was at maximum lift capability. The reality is that I’m probably never going to get anywhere near maximum lift capability with the few items I’m lifting. It’s more likely it will only be a few hundred pounds at a time. Even my rear blade was only 400 lbs.

As noted, simply changing to using a longer chain eliminates the increased load. Meanwhile, a single attachment point is still putting extra stresses on the bucket no matter if you attempt to reinforce it or not. For sure, I won’t be bending my bucket in the middle. Again, the goal of the approach.

You say it’s up to me, but you keep posting. I guess you are mad that I didn’t immediately give up my approach. I hope you aren’t losing sleep over it.

I’m not attacking you. I’m only concerned that others will accept without questioning your deliberate violation of the advice of chain manufacturers.
Example: your statement that the angle in the pic I posted is “less than double”…is a patently dangerous misunderstanding of the actual numbers. If your chain is rated at 10 tons and the set up depicted is utilized then the overload of the chain is more than 14,000 pounds! Doh.

Good luck with that. Keep others well away please.

 

[jimh406]

Example: your statement that the angle in the pic I posted is “less than double”…is a patently dangerous misunderstanding of the actual numbers.

I didn’t say anything about an attack.

You seem to have a problem with math. If the load on the chain is 17.4 tons per side, each link would be 8.4 overloaded. You don’t get to add all of the numbers together.

Btw, you are intentionally violating the design of your bucket as well by both welding to it, and also, lifting from the center. So, please don’t have anyone near you. Joking, but you are over the top.

Again, since you seem to have missed it, I can put my chain at 45 degrees and each hook will be less than your 90 degree single hook that is giving you a chance to bend your bucket. I could also use a spreader bar which would be easy to do and double the total capacity. I could also use a much strong chain to decrease the risk. Meanwhile, you would still be taking a chance to bend your bucket.

Obviously, I am honestly discussing the design. I agree that I had a misunderstanding of the effect of sideforce. But, no matter how hard you try the principles of the approach far exceed the single hook in the center method albeit with a modification to use a 45 degree angle.

 

[chim]

One thing to keep in mind is just how much the loader can (or can't) lift. I'm on my third Kubota equipped with a factory FEL. None have had enough lifting capability to bend the bucket. Can't say that bending a bucket isn't possible. It would be interesting to see some actual damage and an explanation on how it happened.

A few pics from the two most recent tractors below show some of things my buckets have endured without harm. I've lifted from any point on the bucket, dictated by what needed grabbed.

For the first tractor, it was 3/8" chain because it seemed like a good HD approach. There's a 5 gallon bucket full of chains in the garage, mostly 3/8" that don't see much use any more. Now with the largest tractor to date, it's 1/4" grade 70. The WLL for that smaller chain still has 1.5 times the lift capacity of the loader.

 

[Dennis.D]

I have 3 welded hooks on my bucket. 2 on the out side edges of the bucket. Those are mainly to strap 55 gal barrels or... in the bucket for transportation. The one in the center is for lifting things. I think lifting in the center is better for the loader, because it is centered. Lifting on the outer edges is risky in my opinion. If the load shifts you could put all the load on 1 arm that could cause a bent arm or worse. If the load is enough it could tip the tractor.

 

[Willbeone]

If you try hard enough, you can bend the bucket on your Kubota.

 

[Kennyd4110]

I hope this is an ok picture. I probably could have made it a little longer to leave more room for the hook, but it works great.

Obviously, it is easily removable since it’s only links in the hooks. I thought of this approach to avoid a center hook since I heard about buckets being bent from the pressure at a center hook.

View attachment 63915

Just remember, the shorter the chain between the two hooks, the greater the sideload is on them-and that are not really rated for that.