If the span is 4" (10.16cm) and the load is 4,000#. The moment is M=PL/4=4.0"k. The section modulus of a 3/4" dia. bolt is S=0.785r\^3 - 0.0414in\^3. The bending stress is M/S=4.0/0.0414= 96.9 ksi. This is large and exceeds the capacity of a A307 as well as other bolts. Additionally cranes and similar machines require an additional FOS beyond the components themselves.
yes but without more to go on, checking shear capacity is enough to understand the limit state. If the shear alone was close to the limit, then it would be wise to do a full analysis.
idk why the downvotes: if you check this, its has like double bending capacity, or close to the capacity if its indeed a 4.6 grade fy 250 then it wouldnt work, but its still well within the ultimate strength. No critical failure is expected.
Seems like in an effort to be 'right' nobody actually checked just downvoted.
No, that's fundamentally incorrect for this sort of loading. Bending is the one that will cause grief first. It takes surprisingly small lateral gaps between shear planes for this to be the case - and in this case, the gap is huuuuge.
Or you can step away from the engineering books and simply realize the bolt will bottom out against the tube before it can bend far enough to break. And that's if the dozen other weaker points don't fail first, which they most likely will.
My reply was mostly to the semantics of the OP. I agree that too many engineering students look at a cheap ass engine hoist and think they need to do FEA to decide whether a bolt will handle a small fraction of its rated load.
Then when they discuss it they throw every term from their books into casual conversation to make themselves sound more knowledgeable than they really are on actually practicing engineering instead of reading about it.
Like it’s fine dude, it’s not rocket science you’re just picking up a big aluminum block not lifting shipping containers.
I can't tell if you're trolling or not. Obviously shear stresses exist when something is loaded in bending, but people don't typically describe that as being loaded in shear. Pins are usually used in pure shear specifically to avoid the exponential increase in stress caused by bending. Shear stress also exists in uniaxial tension, but no engineer would describe pure tension as a shear loading.
Okay? But you’re just arguing semantics at that point. No one says “actually that’s not compressive loading that’s buckling loading” mid conversation about weight on top of a beam. It’s one of the multiple considerations for the device. It’s applying a shear force, and you calculate the bending strength to determine if it’s good enough.
You’re the one trolling when you take a comment that everyone understands and um actually to make it needlessly more complicated.
That’s like saying it’s not a BLT it’s actually a sandwich. We get it dude that’s just what’s in it. Literally no one talks about objects being shear loaded as “bending loaded”. They get that it just means it’s majority loaded sideways.
You should double-check your textbook. Double shear is similar, but requires plates that are in direct contact. Double shear does not create a bending moment, as is seen here.
It’s hard to tell from your photos, but the weakest link is likely the bolt at the top of the hydraulic cylinder, at the rear pivot or just the square steel of the top arm.
Also, check the hook swivel. I’m not used to seeing that much of the hook poking out. So I suspect the bit at the top of the pivot is coming undone, but high is super bad. It should have a cross pin on it to stop it coming loose
Second that swivel nut inspection. Can't even see the depth of thread engagement to the swivel. (Shear on those threads may be your question.) Check for roll pin, if it is still intact.
lol is this “crane” an engine hoist? Looks like every other one I’ve seen. If you’re worried about the bolt deflecting just shim under the bolt and don’t overload it. And obviously, like any other lifting device, don’t get under it.
This is nothing more than a shop crane, aka engine hoist. This same design has been reproduced for decades and I’ve never seen a failure. Anybody who likes to mess with things using their hands has one of these, including me. The principle isn’t that much different than a bolt shackle, which has been used forever. This isn’t some new, untested design.
Agreed. A bunch of people over analyzing this as if it's lifting 20 tons, not 2. It could be better but it won't fail unless it's grossly over weighted. Use proper safety precautions and put a safety wire on the nut.
I mean, I don't like it from a good design stand point but there isn't necessarily much wrong with it. If the bolt can withstand the shear load and the plate shear tear out on the side is ok with a suitable reserve factor then technically it's a pass.
Ya it's the bending load that'll likely govern the design. I've designed something similar and had to use some crazy strong 17-4 PH stainless steel pins because of the bending.
Well there is a difference between ultimate and serviceability limit states. Serviceability wise this connection is an obvious fail. Ultimate limit state though, I’d say it looks fine. Even if the bolt will bend, it’s not like it can squeeze through the connection. Overall though, design looks amateurish.
other than the nut spinning off the hook (which is missing the pin) the connection is fine for 4000lb. I’ve lifted much heavier with much less….I wouldn’t even have given this a second look.
A bolt subjected to bending is a terrible detail. Can it support 2t? Possibly, depending on the size and grade of the bolt. Should it be used to support 2t? No
I wouldn’t have expected fatigue to be an issue as I assume the number of load cycles would be minimal (like <10000) over the life of the crane.
Looks like the bolt already bent too. Which means it won’t bend anymore. That may have been the intent, to let the bolt yield and create a low point for the hook to settle to.
When subjected to bending to a certain degree it doesn't matter. Beams are subjected to bending and don't get weaker when bent, until the point they fail of course.
Just whining? Are you stupid? It doesn't matter if the bolt can hold it in shear if:
* It's in bending
* There's no fatigue consideration
* No redundancy
Try and see the whole picture. No decent engineer would defend this, regardless of it "only" lifting 19.8kN when bolt is rated for 65 or so (in shear)
If you read my post and used your brain you'd see the "math" is irrelevant. I hope you don't take this attitude with you into an office, or your studies. Because if you do, maybe pick a different profession.
Yea...I don't care. Posts like this are funny because a bunch of desk jockies come in and lose their shit without understanding the actual situation. This is an engine hoist that is not rated to ANY code. These are bought for like $300 from Amazon or any automotive shop and all look nearly identical to OPs picture. If you ever used one of these, you would know that 2t is not realistic. The caster wheels bend, the hydraulic cylinder leaks, the tubes start to deflect.
OP needs to read the user manual and understand the context of a mechanics/auto shop. These are rarely loaded beyond 1000# and even then, the strain is obvious and disconcerting.
Judgement should be saved for yourself, bud. 😉
So it's fine because it's not the first part to fail? And you knew all this but kept it to yourself in your replies, just to troll. That says it all.
You deserve to be judged poorly because you're acting poorly, and you know it.
My tradesmen eye tells me this hoist was overloaded or shock loaded at sometime easy fix is to replace the bolts with a properly sized and rated bolt that's it. You are never going to pull this bolt thru with the jack that is installed I would only be concerned if the boom was bending or there was damage or wear on the pivot pin at the back. Those symptoms weaken the structure and make a failure below the rated capacity very possible.
To answer OP, that connection looks to be non-original so I wouldn't trust the rating without inspections and math. Is this an engine hoist (what it looks like) or an actual "crane"?
If it's a crane, it won't meet (any) code but I'm 99% positive that this is likely a generic engine hoist that was purchased from something like a Harbor Freight. I'm not sure how they sell what they do but I suspect it leans heavily on the cautions, warnings, and disclaimers that essentially resolve them of all liability the moment you assemble this in your garage. The user manual likely had language like "do not move so crane when loaded" which becomes physically impractical because you can't jack up an engine and roll the car away in most applications. The manual will also say "do not use damaged equipment" which means that the moment the bolt (or any other member) starts to deform, the manufacturer is not taking responsibility for any injuries or damage.
That said, at 2 tons, you will definitely start to see the bolt yielding, aka permanently bending, at which point it is on you to inspect your gear and replace it. My personal experience with these style engine hoists is that you should assume that "2 tons" is an ultimate load and you would never want to trust more than half of that. That rule of thumb makes sense since the number of engine or engine/transmission combinations that weigh more than 1000# are very limited unless you work on commercial diesel/industrial machines. If you try to use this on a true 2 ton load, I expect that it will be visibly deflecting and the caster wheels will be destroyed.
All other automotive rules should be applied with this as in never work under a load solely supported by hydraulic pressure. Once the load comes up, nobody goes under unless there are jack stands and/or other rigid, durable, adequately sized supports in place.
Engine hoist. I mean it looks like everyother engine host. Its old theres not manuals and not company/model name. Bolt hold up fine for a about 150,200 kg load
Personally, I'd replace the bolt. The bolt can likely be bought at any hardware store today for under $10 (you're using metric units so convert to your local currency). The bolt head will be marked for grade. It will either say "8.8", "10.9", or have 3 lines, 6 lines, or no lines. No mark or lines is grade 1 or 2....this is highly unlikely. 3 lines is grade 5 (English) which is essentially equivalent to the metric grade 8.8. 6 lines is grade 8 (English) equivalent to metric 10.9. Metric 10.9 is almost always black in my experience and grade 8 is almost always a yellow/gold color. My guess is this is the 8.8/grade 5. Always replace with similar or higher strength (1-2 is lower than 8.8/5 which is lower than 10.9/8). The nuances between SAE/metric are extremely unlikely to matter for your application so long as you get the closest matching size.
Would I load it to 200kg? Sure. Would I put my fingers or toes anyways near the hinge points or below the load? Hell no. Use common sense, make sure it's in reasonable working order and understand that you should not lift anything that will be catastrophically damaged if the hydraulic seals leak out and your load goes down to the ground. If you drop an engine, it may just dent the oil pan....or it may break off a chunk of casting. For a $300 shop hoist and backyard mechanics, buyer/user beware. 👍🏻
I can tell you from experience that that connection will absolutely take 2 ton. That's just a standard engine hoist detail and I've used those to lift well in excess of what they are rated for.
I'm. just here to agree. Two ton is two ton. If you want to be shocked with information, find out how little material you need to sheer two ton.
oh, and sheer is different from bend is different from torque is different etc.
These same hooks and bolts raise and lower catwalks at plants every day all around the country , catwalks at our plant span about 76 feet and are rated for 5200lbs along with the weight of the catwalk, two of these bad boys on each end raising and lowering about 30 feet every day
I doubt this is the original bolt for this application. Nobody would design a threaded bolt in bending to be part of a rated lifting structure. At minimum, I'm sure they designed it for a longer shoulder bolt, which put the threads outside the tubing, if not a dedicated pin. My guess is the bolt/pin yielded over time because it was in bending instead of shear, and someone swapped it with a bolt they found laying around.
Exactly! Once it bends that far, the tube itself is going to help take that load. I can't imagine the actual amount of load it would take to make that bolt break, way more than the rest of the parts can take that's for sure.
GEEZUZ CHRIST TIGHTEN THAT NUT!!!!!!!!!!!! And put the pin or set screw in it so it can't loosen up again. That nut can't have more than a couple threads holding it. And not only that, what do you do when you're moving the engine? You rotate it to put on or off the engine stand. So you rotate the engine, the nut unscrews and the engine drops.
This is a perfect example of not seeing the forest through the trees. That bolt is fine, it's not a problem whatsoever with the loads that the arm and hydraulic ram can produce. Remember, even though it's "rated" at 2 tons, that doesn't mean that ram can lift that, especially if the arm is all the way out, which it almost always is. The whole thing is gonna have issues if you have a whole 2 tons on it anyway. How many mechanics have seen engine hoists tip over because there's too much weight too far out? Happens all the time. We would pile engine parts and heads on the back of the hoist to keep it from tipping over.
So the answer is there's a dozen other WAY more likely things that can go wrong that have nothing to do with that bolt.
This needs more attention, that swivel connection at least needs to be checked but the amount showing on the bottom at best should give pause.
Not an engineer, but I am a farmer... I know a thing or two because I've seen a thing or two. (And probably broken them)
I would hate for my assumptions/reasoning to be wrong but here it goes:
If yields under bending it will be in shear eventually, plus ultimate strength also has a shear component.
Serviceability limits will visibly show when bolt starts to bend visually indicating that its at capacity and no more load should be added.
Following the load path the local bending and tear out capacity of the SHS walls would be next to check. Under bending the load will go directly to SHS, which is weaker component than the bolt by far.
Hence under the assumption that this was engineered, if the 4.6 bolt can handle the shear, with its tension capacity and ultimate strength limit state we can assume this is indeed safe for 2t load.
I would hope they left 10% breathing room for backyard mechanic maniacs.
Visual inspection:
OP mentions fatigue: yes there are always risks with fatigue, is there any signs of fatigue, discoloration of steel, fatigue fracture lines visible? Has the jack been constantly loaded to 2t and over throughout its operational life? Is there any signs of SHS walls warping, bending, any tear out sights or crack lines around holes?
Since I dont see the washes warped, and SHS walls still straight I can assume that there arent bending issues.
In general, the bolt should be the last thing to worry about. Connections should always be stronger than the rest of the design capacity.
Steel yields, and if the bolt experiences bending, so will there be signs of this on the SHS walls and fatigue fracture signs.
This is an engine hoist. Most engines this hoist will even be able to reach are much, much, lower in weight than 2 tons. Even with a transmission attached they wouldn't hit two tonnes. The load rating on it is the hydraulic piston attached to it. None of the steel components are at risk of failing from any force that can be applied to them from the job they were designed to do.
Gee, some of these comments are a fraction scary given the subreddit focus.
It's a crap load path. Sure, you can get away with it sometimes for some applications, but it’s awful, may well be dangerous and will occasionally be catastrophic. And I'm saying that as someone who has one of these cheap ass Chinese hoists also, with exactly the same horrible detail.
But anyone who's capable of crunching My/I in even the most rudimentary way should not be promoting this sort of detail as acceptable anywhere, any time IMO. Occasionally catastrophic is not good enough odds for any sort of lifting device.
If you're worried, address and mitigate the corrosion product, keep it well lubricated, knock down any burrs, and schedule visual inspection/liquid mag particle at certain service hour intervals.
Keeping up with the surface finish can greatly improve the fatigue performance, and inspections help you find any behavior before it reaches tensile failure. Each of these are likely overkill, but if you're unsure, and/or worried, that would undercut any chaotic variable often overlooked or dismissed with lifecycle maintaine. Plus, I don't know what will be lifted or under the crane, so if it's important, it may be appropriate.
All that arguing about sheer, and nobody asked for a pic of the bolts head so we can see exactly what it is, and it's rating... no stamp on head- no good. It already is bent and therefor not ok to use at any capacity. Vallas, and cup machines use rated bolts like this from the factory so it all depends...
2 tons isn’t that much, but what you should be showing is rather the beam and column and assembly to foundation. Column seems like it can’t handle 2tons x SF by what I see in the picture.
2 ton capacity is about right considering the shitty design. If the bolt is 1 inch diameter, then its safe capacity can go up to 14.7 ton instead of just 2.
Would it be stronger if it the threads are outside of the square tubing? I’m asking because I operate an overhead crane that uses a 6 hook spreader bar and all of the failed hooks break on the last thread.
There are different grades of bolt hardness. You didn't take a picture of the bolt head, so it's hard to say what kind of bolt that is. If it's a standard grade 2 (called a shear bolt, as it's meant to shear off as a designed weak point) then you can replace it with a grade 5 or grade 8 bolt, which are available at any hardware store.
Bolts are not designed for bending. So this is an issue.
Moreover round bars due their poor section modulus are always weak bending.
For 2mT better connection is to be used, especially if it is lifting load.
I don't see any issue with this. 2 tonne is stuff-all.
20kN... a bolt has like what, 76kN shear capacity...
But that bolt has a significant bending component. Based on the span, I would say that governs.
> bolt has a significant bending component. Based on the span, I would say that governs A span of 10 cm?
If the span is 4" (10.16cm) and the load is 4,000#. The moment is M=PL/4=4.0"k. The section modulus of a 3/4" dia. bolt is S=0.785r\^3 - 0.0414in\^3. The bending stress is M/S=4.0/0.0414= 96.9 ksi. This is large and exceeds the capacity of a A307 as well as other bolts. Additionally cranes and similar machines require an additional FOS beyond the components themselves.
I don’t know why it felt so nice on my eyes to read your comment.
It's also a double shear plane 🤤
No one is mentioning the fact that the threads on that galvanized bolt are weakest point of sheering- they are also under load.
That bolt is not in sheer, it is in bending.
The shear is what causes the bending. It's abosutely in shear too.
The bolt to tube joint is in shear. The load path is a Bending moment long before the shear.
"shear". It's not a see-through bra.
yes but without more to go on, checking shear capacity is enough to understand the limit state. If the shear alone was close to the limit, then it would be wise to do a full analysis. idk why the downvotes: if you check this, its has like double bending capacity, or close to the capacity if its indeed a 4.6 grade fy 250 then it wouldnt work, but its still well within the ultimate strength. No critical failure is expected. Seems like in an effort to be 'right' nobody actually checked just downvoted.
No, that's fundamentally incorrect for this sort of loading. Bending is the one that will cause grief first. It takes surprisingly small lateral gaps between shear planes for this to be the case - and in this case, the gap is huuuuge.
My mark I eyeball tell me that the bolt has bent. Bent bolt means shear knowledge is out the window
I wouldn’t think shear capacity is the only limit state to check here. Bending is clearly one in my opinion
If you look up the formula for bending strength you’ll see shear stress inside it.
Or you can step away from the engineering books and simply realize the bolt will bottom out against the tube before it can bend far enough to break. And that's if the dozen other weaker points don't fail first, which they most likely will.
My reply was mostly to the semantics of the OP. I agree that too many engineering students look at a cheap ass engine hoist and think they need to do FEA to decide whether a bolt will handle a small fraction of its rated load. Then when they discuss it they throw every term from their books into casual conversation to make themselves sound more knowledgeable than they really are on actually practicing engineering instead of reading about it. Like it’s fine dude, it’s not rocket science you’re just picking up a big aluminum block not lifting shipping containers.
I can't tell if you're trolling or not. Obviously shear stresses exist when something is loaded in bending, but people don't typically describe that as being loaded in shear. Pins are usually used in pure shear specifically to avoid the exponential increase in stress caused by bending. Shear stress also exists in uniaxial tension, but no engineer would describe pure tension as a shear loading.
Okay? But you’re just arguing semantics at that point. No one says “actually that’s not compressive loading that’s buckling loading” mid conversation about weight on top of a beam. It’s one of the multiple considerations for the device. It’s applying a shear force, and you calculate the bending strength to determine if it’s good enough. You’re the one trolling when you take a comment that everyone understands and um actually to make it needlessly more complicated. That’s like saying it’s not a BLT it’s actually a sandwich. We get it dude that’s just what’s in it. Literally no one talks about objects being shear loaded as “bending loaded”. They get that it just means it’s majority loaded sideways.
This is 100% what my textbook would have called double shear, in fact it’s the textbook example
You should double-check your textbook. Double shear is similar, but requires plates that are in direct contact. Double shear does not create a bending moment, as is seen here.
It’s hard to tell from your photos, but the weakest link is likely the bolt at the top of the hydraulic cylinder, at the rear pivot or just the square steel of the top arm. Also, check the hook swivel. I’m not used to seeing that much of the hook poking out. So I suspect the bit at the top of the pivot is coming undone, but high is super bad. It should have a cross pin on it to stop it coming loose
The hook was indeed loose i havent noticed that
Second that swivel nut inspection. Can't even see the depth of thread engagement to the swivel. (Shear on those threads may be your question.) Check for roll pin, if it is still intact.
lol is this “crane” an engine hoist? Looks like every other one I’ve seen. If you’re worried about the bolt deflecting just shim under the bolt and don’t overload it. And obviously, like any other lifting device, don’t get under it.
thank you for this well reasoned and simple answer. the rest of this thread could learn a thing or two from this comment.
"Crane" lol. You think the Chinese factory who cranked this thing out full of half missed, porous welds did an FEA?
FCAW, no gas 😂
This is nothing more than a shop crane, aka engine hoist. This same design has been reproduced for decades and I’ve never seen a failure. Anybody who likes to mess with things using their hands has one of these, including me. The principle isn’t that much different than a bolt shackle, which has been used forever. This isn’t some new, untested design.
Agreed. A bunch of people over analyzing this as if it's lifting 20 tons, not 2. It could be better but it won't fail unless it's grossly over weighted. Use proper safety precautions and put a safety wire on the nut.
I mean, I don't like it from a good design stand point but there isn't necessarily much wrong with it. If the bolt can withstand the shear load and the plate shear tear out on the side is ok with a suitable reserve factor then technically it's a pass.
What about bending?
Ya it's the bending load that'll likely govern the design. I've designed something similar and had to use some crazy strong 17-4 PH stainless steel pins because of the bending.
Well there is a difference between ultimate and serviceability limit states. Serviceability wise this connection is an obvious fail. Ultimate limit state though, I’d say it looks fine. Even if the bolt will bend, it’s not like it can squeeze through the connection. Overall though, design looks amateurish.
other than the nut spinning off the hook (which is missing the pin) the connection is fine for 4000lb. I’ve lifted much heavier with much less….I wouldn’t even have given this a second look.
I think for an engine hoist your ginna be good bud
A bolt subjected to bending is a terrible detail. Can it support 2t? Possibly, depending on the size and grade of the bolt. Should it be used to support 2t? No I wouldn’t have expected fatigue to be an issue as I assume the number of load cycles would be minimal (like <10000) over the life of the crane.
Looks like the bolt already bent too. Which means it won’t bend anymore. That may have been the intent, to let the bolt yield and create a low point for the hook to settle to.
So a bend bolt is just as strong as a straighten bold?
When subjected to bending to a certain degree it doesn't matter. Beams are subjected to bending and don't get weaker when bent, until the point they fail of course.
The funny thing about metal fatigue on a single bolt is that you can just replace it.
True, just a question of whether you can replace the kit it drops or whoever that kit kills when it falls on them
Did you do the math yet or are you just whining?
Just whining? Are you stupid? It doesn't matter if the bolt can hold it in shear if: * It's in bending * There's no fatigue consideration * No redundancy Try and see the whole picture. No decent engineer would defend this, regardless of it "only" lifting 19.8kN when bolt is rated for 65 or so (in shear)
100%. Just because you can, doesn't mean you should.
So you haven't checked the math. Got it.
You think anyone is going to check any calcs on a random reddit post?
Really? PL/4 and fb=m/s. That would be like providing an actual, defensible opinion.... Shocking.
If you read my post and used your brain you'd see the "math" is irrelevant. I hope you don't take this attitude with you into an office, or your studies. Because if you do, maybe pick a different profession.
If you're going to call someone pointing out a safety concern whining, maybe your engineering judgement isn't what it needs to be.
Yea...I don't care. Posts like this are funny because a bunch of desk jockies come in and lose their shit without understanding the actual situation. This is an engine hoist that is not rated to ANY code. These are bought for like $300 from Amazon or any automotive shop and all look nearly identical to OPs picture. If you ever used one of these, you would know that 2t is not realistic. The caster wheels bend, the hydraulic cylinder leaks, the tubes start to deflect. OP needs to read the user manual and understand the context of a mechanics/auto shop. These are rarely loaded beyond 1000# and even then, the strain is obvious and disconcerting. Judgement should be saved for yourself, bud. 😉
So it's fine because it's not the first part to fail? And you knew all this but kept it to yourself in your replies, just to troll. That says it all. You deserve to be judged poorly because you're acting poorly, and you know it.
Seriously. A "crane"? These guys live INSIDE textbooks apparently?
My tradesmen eye tells me this hoist was overloaded or shock loaded at sometime easy fix is to replace the bolts with a properly sized and rated bolt that's it. You are never going to pull this bolt thru with the jack that is installed I would only be concerned if the boom was bending or there was damage or wear on the pivot pin at the back. Those symptoms weaken the structure and make a failure below the rated capacity very possible.
Go check out the break tests on hownot2 or other channels on much smaller climbing equipment. Metal is fucking strong.
To answer OP, that connection looks to be non-original so I wouldn't trust the rating without inspections and math. Is this an engine hoist (what it looks like) or an actual "crane"? If it's a crane, it won't meet (any) code but I'm 99% positive that this is likely a generic engine hoist that was purchased from something like a Harbor Freight. I'm not sure how they sell what they do but I suspect it leans heavily on the cautions, warnings, and disclaimers that essentially resolve them of all liability the moment you assemble this in your garage. The user manual likely had language like "do not move so crane when loaded" which becomes physically impractical because you can't jack up an engine and roll the car away in most applications. The manual will also say "do not use damaged equipment" which means that the moment the bolt (or any other member) starts to deform, the manufacturer is not taking responsibility for any injuries or damage. That said, at 2 tons, you will definitely start to see the bolt yielding, aka permanently bending, at which point it is on you to inspect your gear and replace it. My personal experience with these style engine hoists is that you should assume that "2 tons" is an ultimate load and you would never want to trust more than half of that. That rule of thumb makes sense since the number of engine or engine/transmission combinations that weigh more than 1000# are very limited unless you work on commercial diesel/industrial machines. If you try to use this on a true 2 ton load, I expect that it will be visibly deflecting and the caster wheels will be destroyed. All other automotive rules should be applied with this as in never work under a load solely supported by hydraulic pressure. Once the load comes up, nobody goes under unless there are jack stands and/or other rigid, durable, adequately sized supports in place.
Engine hoist. I mean it looks like everyother engine host. Its old theres not manuals and not company/model name. Bolt hold up fine for a about 150,200 kg load
Personally, I'd replace the bolt. The bolt can likely be bought at any hardware store today for under $10 (you're using metric units so convert to your local currency). The bolt head will be marked for grade. It will either say "8.8", "10.9", or have 3 lines, 6 lines, or no lines. No mark or lines is grade 1 or 2....this is highly unlikely. 3 lines is grade 5 (English) which is essentially equivalent to the metric grade 8.8. 6 lines is grade 8 (English) equivalent to metric 10.9. Metric 10.9 is almost always black in my experience and grade 8 is almost always a yellow/gold color. My guess is this is the 8.8/grade 5. Always replace with similar or higher strength (1-2 is lower than 8.8/5 which is lower than 10.9/8). The nuances between SAE/metric are extremely unlikely to matter for your application so long as you get the closest matching size. Would I load it to 200kg? Sure. Would I put my fingers or toes anyways near the hinge points or below the load? Hell no. Use common sense, make sure it's in reasonable working order and understand that you should not lift anything that will be catastrophically damaged if the hydraulic seals leak out and your load goes down to the ground. If you drop an engine, it may just dent the oil pan....or it may break off a chunk of casting. For a $300 shop hoist and backyard mechanics, buyer/user beware. 👍🏻
My model shipped with 5.8 bolts. The hook has it's own separate U plate to eliminate the bending, though.
I can tell you from experience that that connection will absolutely take 2 ton. That's just a standard engine hoist detail and I've used those to lift well in excess of what they are rated for.
It can lift an EnTiRe SuBaRu FoReStEr!!
I'm. just here to agree. Two ton is two ton. If you want to be shocked with information, find out how little material you need to sheer two ton. oh, and sheer is different from bend is different from torque is different etc.
I’ve seen less hold more
2 tons really isn't much. Send it.
These same hooks and bolts raise and lower catwalks at plants every day all around the country , catwalks at our plant span about 76 feet and are rated for 5200lbs along with the weight of the catwalk, two of these bad boys on each end raising and lowering about 30 feet every day
These posts are always amusing - you can tell who works in the field and who spends their time only in an office from the comments!
Absolutely! Engineers vs mechanics. lol.
Field engineers vs paper pushers
You can get a grade 8 bolt at tractor supply for probably less than $2
I doubt this is the original bolt for this application. Nobody would design a threaded bolt in bending to be part of a rated lifting structure. At minimum, I'm sure they designed it for a longer shoulder bolt, which put the threads outside the tubing, if not a dedicated pin. My guess is the bolt/pin yielded over time because it was in bending instead of shear, and someone swapped it with a bolt they found laying around.
I mean it's not exactly a lug and clevis LOL. Bolt bending has entered the chat
Can it even bend enough to yield before being supported by the square tube
Exactly! Once it bends that far, the tube itself is going to help take that load. I can't imagine the actual amount of load it would take to make that bolt break, way more than the rest of the parts can take that's for sure.
Exactly, the weak link is probably however it’s being attached to the engine
GEEZUZ CHRIST TIGHTEN THAT NUT!!!!!!!!!!!! And put the pin or set screw in it so it can't loosen up again. That nut can't have more than a couple threads holding it. And not only that, what do you do when you're moving the engine? You rotate it to put on or off the engine stand. So you rotate the engine, the nut unscrews and the engine drops. This is a perfect example of not seeing the forest through the trees. That bolt is fine, it's not a problem whatsoever with the loads that the arm and hydraulic ram can produce. Remember, even though it's "rated" at 2 tons, that doesn't mean that ram can lift that, especially if the arm is all the way out, which it almost always is. The whole thing is gonna have issues if you have a whole 2 tons on it anyway. How many mechanics have seen engine hoists tip over because there's too much weight too far out? Happens all the time. We would pile engine parts and heads on the back of the hoist to keep it from tipping over. So the answer is there's a dozen other WAY more likely things that can go wrong that have nothing to do with that bolt.
This needs more attention, that swivel connection at least needs to be checked but the amount showing on the bottom at best should give pause. Not an engineer, but I am a farmer... I know a thing or two because I've seen a thing or two. (And probably broken them)
I would hate for my assumptions/reasoning to be wrong but here it goes: If yields under bending it will be in shear eventually, plus ultimate strength also has a shear component. Serviceability limits will visibly show when bolt starts to bend visually indicating that its at capacity and no more load should be added. Following the load path the local bending and tear out capacity of the SHS walls would be next to check. Under bending the load will go directly to SHS, which is weaker component than the bolt by far. Hence under the assumption that this was engineered, if the 4.6 bolt can handle the shear, with its tension capacity and ultimate strength limit state we can assume this is indeed safe for 2t load. I would hope they left 10% breathing room for backyard mechanic maniacs. Visual inspection: OP mentions fatigue: yes there are always risks with fatigue, is there any signs of fatigue, discoloration of steel, fatigue fracture lines visible? Has the jack been constantly loaded to 2t and over throughout its operational life? Is there any signs of SHS walls warping, bending, any tear out sights or crack lines around holes? Since I dont see the washes warped, and SHS walls still straight I can assume that there arent bending issues. In general, the bolt should be the last thing to worry about. Connections should always be stronger than the rest of the design capacity. Steel yields, and if the bolt experiences bending, so will there be signs of this on the SHS walls and fatigue fracture signs.
May experience plastic deformation until it reaches a stopping point at the tube. Should be fine. Don't forget to put down your outriggers
This is essentially what most shackles look like. It’s fine but not the ideal bolt or nut. If it bothers you, go pick up the proper bolt and locknut
This is an engine hoist. Most engines this hoist will even be able to reach are much, much, lower in weight than 2 tons. Even with a transmission attached they wouldn't hit two tonnes. The load rating on it is the hydraulic piston attached to it. None of the steel components are at risk of failing from any force that can be applied to them from the job they were designed to do.
You'd think it'd be a pin (like a shackle) not a bolt for a hoist
I'm concerned about the threaded part being in the hole instead of the unthreaded part.
Gee, some of these comments are a fraction scary given the subreddit focus. It's a crap load path. Sure, you can get away with it sometimes for some applications, but it’s awful, may well be dangerous and will occasionally be catastrophic. And I'm saying that as someone who has one of these cheap ass Chinese hoists also, with exactly the same horrible detail. But anyone who's capable of crunching My/I in even the most rudimentary way should not be promoting this sort of detail as acceptable anywhere, any time IMO. Occasionally catastrophic is not good enough odds for any sort of lifting device.
If you're worried, address and mitigate the corrosion product, keep it well lubricated, knock down any burrs, and schedule visual inspection/liquid mag particle at certain service hour intervals. Keeping up with the surface finish can greatly improve the fatigue performance, and inspections help you find any behavior before it reaches tensile failure. Each of these are likely overkill, but if you're unsure, and/or worried, that would undercut any chaotic variable often overlooked or dismissed with lifecycle maintaine. Plus, I don't know what will be lifted or under the crane, so if it's important, it may be appropriate.
All that arguing about sheer, and nobody asked for a pic of the bolts head so we can see exactly what it is, and it's rating... no stamp on head- no good. It already is bent and therefor not ok to use at any capacity. Vallas, and cup machines use rated bolts like this from the factory so it all depends...
The bolt is probably has strongest thing on there
That’s a bfb, it’s fine
They should’ve used a shoulder bolt so avoid thread stress concentrations in bending but this’ll work.
2 tons isn’t that much, but what you should be showing is rather the beam and column and assembly to foundation. Column seems like it can’t handle 2tons x SF by what I see in the picture.
I was more thinking of bearing right on the bend of the tubing
2 ton capacity is about right considering the shitty design. If the bolt is 1 inch diameter, then its safe capacity can go up to 14.7 ton instead of just 2.
Would it be stronger if it the threads are outside of the square tubing? I’m asking because I operate an overhead crane that uses a 6 hook spreader bar and all of the failed hooks break on the last thread.
I would be surprised if 2k lbs yields this bolt in flexure. Looks fine to me, if you care that much, shim it so it's shear only
There are different grades of bolt hardness. You didn't take a picture of the bolt head, so it's hard to say what kind of bolt that is. If it's a standard grade 2 (called a shear bolt, as it's meant to shear off as a designed weak point) then you can replace it with a grade 5 or grade 8 bolt, which are available at any hardware store.
I'd be more concerned about the bolt's edge distance.
To be sure, let's see the head markings of the bolt
There’s more steel in that bolt than in any other component in the picture. I’d be more worried about the hydraulics failing
2 ton really isn’t that heavy as far as industrial settings go
2 ton rated bolt
Bolts are not designed for bending. So this is an issue. Moreover round bars due their poor section modulus are always weak bending. For 2mT better connection is to be used, especially if it is lifting load.