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Thread: A strength of materials (steel) question

  1. #11
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    Thanks very much JCB, thatís most helpful info. The picture shows just fine. The rectangular tube is another good option, thatís how the clamp on ones I have now are constructed, but of much heavier material.

    Might be a better option than the channel. Appreciate the input.

    Weirdsci, thatís also an interesting thought. Iíve not looked into that but Iím sure there have to be any number of such places around here. Food for thought. Thanks.


    Sent from my iPhone using Tapatalk

  2. #12
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    I built a 3pt hitch fork carrier for my tractor years ago, but I used std 4' forklift forks so I can't be much help, but we have some shop built extensions at work made from 6" channel and I can neither confirm, nor deny that they've lifted far beyond what they should have..... I think you'd be fine with 6" channel, or even 4". A set of 4" channel forks, 36" long on a QA plate should be well within the lifting capacity of your loader provided construction was up to snuff.

  3. #13
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    Hi,

    I agree with the observation that your hydraulics will bypass before you break the loader. And with a 600lbs lift limit, nearly any type of steel is "good enough".

    I would however, choose channel over tube or solid for forks if you are going to make the whole thing yourself. Channel will be lighter, (important for your application), and in the practical world, nearly as strong as full tube. And channel is what fork extensions as used on "real" forklifts are made from, so it's plenty strong enough for you.

    Only caution I will give is about overloading the spindles on the front axles. When you start adding weight in the back to prevent lifting of the rear end, you start increasing the risk of snapping a spindle on the front end. I've seen more than one farm tractor with a loader on it break a spindle when lifting heavy loads with a front end loader. If you need to ballast the back end, you've probably already exceed what the front was meant to carry.
    If you think you understand what is going on, you haven't been paying attention.

  4. #14
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    As an FYI the channel you proposed (C3x5) to use in the weak axis as a fork is around .25x the strength of 3x2x3/16" tube and .33x of 3x2x1/8" tube. Turn them both upright and they're very close. Channel is just not designed to be laid down and it'd be much more likely to buckle. Tube is slightly more expensive by size and much better in this application. Up size the channel to match strength wise and it will weigh almost double and therefore cost more as well. Unless you have something laying around to use, tube is the right choice.

    Edit: I see another post recommending channel. Are you gentleman engineers? Fork extensions are nearly fully supported by the fork, and the fork is doing critical work at the bend, it is not the same as a scratch build fork. Channel is not better in this application.
    Last edited by JCByrd24; 08-22-2019 at 11:02 AM.

  5. #15
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    Quote Originally Posted by JCByrd24 View Post
    As an FYI the channel you proposed (C3x5) to use in the weak axis as a fork is around .25x the strength of 3x2x3/16" tube and .33x of 3x2x1/8" tube. Turn them both upright and they're very close. Channel is just not designed to be laid down and it'd be much more likely to buckle. Tube is slightly more expensive by size and much better in this application. Up size the channel to match strength wise and it will weigh almost double and therefore cost more as well. Unless you have something laying around to use, tube is the right choice.

    Edit: I see another post recommending channel. Are you gentleman engineers? Fork extensions are nearly fully supported by the fork, and the fork is doing critical work at the bend, it is not the same as a scratch build fork. Channel is not better in this application.
    NOT an Engineer, but I 100% agree with the rest of your post, and get what you're saying but we're only talking 600lbs total lifting capacity here......Never said channel would be "better", merely stating it should be adequate for the task at hand.
    Last edited by Dan Dubeau; 08-22-2019 at 11:38 AM.

  6. #16
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    Roger that Dan, didn't mean to come off rude, the OP did inquire about channel after all, just wanted to provide more info after the second recommendation of channel including that they'd be lighter. I tend to agree with ya that it'd probably work, but I'm not going to run the numbers in support of channel and simply wouldn't advise it if the OP is buying material. Buckling is squirrelly.

    I should also correct dalee's statement regarding the front spindle axles and ballast, as it's backwards. I don't doubt his experience, but many older farm tractors simply were not designed to have loaders on them period. The addition of rear ballast may have saved some broken front axles. The math is very simple that a load on the back will reduce the weight on the front axles with our without a loader.

    Every sub-compact/compact tractor sold today is designed with a loader in mind and has a pretty stout front axle. In addition though, every one of them warns of the need for proper ballast when using the front end loader. Loaded tires alone are rarely enough. This is primarily for safety against tipping over, but also reduces the load on the front axle substantially. The tractors hydraulics limit the lifting capability, not the ability of the rear tires to stay on the ground.

  7. #17
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    Quote Originally Posted by JCByrd24 View Post
    As an FYI the channel you proposed (C3x5) to use in the weak axis as a fork is around .25x the strength of 3x2x3/16" tube and .33x of 3x2x1/8" tube. Turn them both upright and they're very close. Channel is just not designed to be laid down and it'd be much more likely to buckle. Tube is slightly more expensive by size and much better in this application. Up size the channel to match strength wise and it will weigh almost double and therefore cost more as well. Unless you have something laying around to use, tube is the right choice.

    Edit: I see another post recommending channel. Are you gentleman engineers? Fork extensions are nearly fully supported by the fork, and the fork is doing critical work at the bend, it is not the same as a scratch build fork. Channel is not better in this application.
    Again, this along with the other replies are all great info. I'm not stuck on using channel, it was just a starting point guess. I'll be purchasing material so will just buy what is best for my application. This is not quite a DoD "cost is no object" environment, but I am willing to spend what things cost to get the right stuff for the job.

    I appreciate your input JCB, and the fact that you have actually done both the calculations as well as the real life testing on this. I'm the wrong flavor of engineer to make these sort of judgements based on the math.

    I'd really appreciate it if you could verify what exactly the tube and wall thickness was when you have the chance. It would be good to know as I could more or less duplicate what you've done. Seems that you have already solved the same "problem" I am looking to solve.

    I do plan to check out a few forklift boneyards if I can find one around here that will talk to me. That can be a challenge in these parts at times, lots of skittishness about walk-ins with seemingly nutty project ideas...

    Dalee, I understand the cautions about overloading things. I'm still a bit of a noob to using a tractor so tend to be pretty cautious about what I do and how I do it. Your warning is duly noted. Thanks.

    Thanks to all of you for taking the time to reply.

  8. #18
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    I will check wall thickness when I'm home tonight.

  9. #19
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    Quote Originally Posted by JCByrd24 View Post

    <SNIP stuff>
    Every sub-compact/compact tractor sold today is designed with a loader in mind and has a pretty stout front axle. In addition though, every one of them warns of the need for proper ballast when using the front end loader. Loaded tires alone are rarely enough. This is primarily for safety against tipping over, but also reduces the load on the front axle substantially. The tractors hydraulics limit the lifting capability, not the ability of the rear tires to stay on the ground.
    This is indeed the case with mine. It came equipped with the matched front end loader new from the factory. I've not lifted all that much with it, but you can surely feel the balance change when you scoop a good bucketful of dirt.

  10. #20
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    Quote Originally Posted by JCByrd24 View Post
    I will check wall thickness when I'm home tonight.
    Thank you sir. Much appreciated.

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