Chain Block

Because gravity works that way.

I've never used chain blocks myself but I've seen others use them to move something horizontally.

I don't know if that's allowed or bad practice but it shows that chain blocks can be used for horizonal pulling purposes.

It is bad practice to use any form of certified lifting equipment for pulling; the two categories of equipment must be kept separate from each other as regards function.

The reason is that, while the load on a piece of lifting equipment can be regulated so that the safe working load [SWL] is never exceeded, the same is not the case with pulling equipment, which doesn't need to be tested and certified for lifting, and is subject to loads of a largely unknown magnitude.

If the SWL is exceeded on a piece of lifting equipment, perhaps by using it to pull, then there remains a risk that the overload has affected the equipment in some way that will cause it to fail unexpectedly in the future while lifting, perhaps with spectacular, expensive and fatal consequences.

Hmmm, I'll have to research on that. I've seen this done practically everywhere and I've never seen any safety officer say anything about it.

It'll give our safety officer something to do, heh heh.

Principle: Would one use a car's tow-rope to pick it up using a crane?

'Course not. A tow-rope's load rating probably doesn't reach half or 3/4 of the car's weight. But that's the thing there.

If the horizontal load doesn't exceed the chain block's rating, can we still use it for that? If not, why?

To illustrate the matter further, discuss the matter with the inspector-surveyor of the insurance company that underwrites an organisation's liability in connection with lifting equipment. That individual will explain more, not necessarily so politely...

Two hypothetical tow-ropes, each with a rating of 3/4 of the hypothetical car's weight are now to be used together, to pick the car up with a hypothetical crane. As a matter of principle, would one attempt the lift using only this tackle? Would it make a difference if one owned the car? Or owned the crane? Or owned the hypothetical building standing in front of the crane or behind it?

Keep going....

Stay cool PW. If you say it's wrong, you probably know the reason for it. I don't.

As I said, I'll check up on it. No need to get upset.

No, no. Complete chill. No offence intended! Follow the reasoning, for here comes the rest of the story:....

<The programme opens with titles and credits, and zooms to an image of a crane in a factory premises, with a car suspended from the hook>

As the lift is taking place with the 2 x ³/₄-car-weight-rated tow-ropes, the works foreman comes around the corner. Seeing the car 60 feet up in the air and still rising his face goes as white as a sheet.

"Stop that lift!", he screeches.

"Why?", ask several bystanders.

"Beacuse 'Stinky Pete' borrowed those tow-ropes last week to pull out a tree stump. He earned a few quid from helping a mate of his, poor old beggar - I took pity upon him as he hasn't much in the way of belongings and he needed the cash. We weren't even using those tow-ropes at the time. I hear he spent his last penny on a couple of bottles of the hard stuff. But that's not the issue. The thing is, he stretched one of them and I noticed that it was a bit frayed. I was going to replace it, but then I've got waylaid by other things, and they're only tow ropes, after all. I didn't imagine anyone would use them for lifting...", replied the foreman, in a bit of a panic.

At that exact moment there is a sudden tearing sound, and a swishing noise. One of the two ropes parts and the car swings violently towards the ground. The crane rocks forwards and backwards, ringing the alarm bells in the cab to the consternation of the crane driver. Then the second rope, now overloaded by a factor of 1.3 recurring as far as its static load is concerned and even further by the rocking motion of the car as the engine swings downwards, tears apart with a loud snap. The ends of the unloaded rope snake about, violently. The car plummets towards the ground. Several start running away. The crane rocks back on its supports and the operator leaps from the cab.

1.94 seconds later: BAAAAAAAAANG! The car hits the ground with a closing speed at the point of impact of 42.3mph. Cripes (no.1) - that was the Managing Director's husband's car!

Clatter, scrape, rumble in the background. Something falls off the crane. It wobbles and stabilises itself by leaning against a building and sliding sideways, knocking out a few courses of brick. Cripes (no.2) - that crane will cost a lot to sort out! So will the building!

It turns out three chaps playing cards in the canteen inside the same building are hurt by falling brickwork. Two of them are working machinery crucial to the successful operation of the business. The dust settles.

Someone, somewhere, has made a phone call. A few minutes later the siren of an ambulance can be heard in the distance. It gets closer. No-one on site seems to know quite what to do. They start shouting at each other; the words, "your fault" seem to be quite popular this morning.

About half an hour later an individual in a high visibility jacket, hard hat and toe-tector boots drives up to the security booth and demands to be let in, as required by Statute. The phone rings. It is the security guard. Yes, OK, let him in. He's the Health & Safety Incident Officer. Oh, cripes (No.4) <Visual effect of zooming, twisting camera looking at PWSlack's face, expressing anguish>

After an hour or so, during which time the ambulance leaves with the three injured souls in it, he arrives at the foreman's office, having taken various measurements, notes and photographs along the way. The foreman is looking nervous. The Incident Officer knows the weight of the car, because he has the manufacturer's information back at his office. The next thing he wants to see are the test records for the crane, the assessment records for the individuals carrying out the lift, and the test certificates for the tackle used to execute the lift. Cripes (no.5) - they used pulling equipment to do a lift...

'Stinky Pete' is seen in the distance, scurrying away...

<Roll credits. Fade to solemn music. "Now on Channel 4, Big Brother!">

The above story attempts to illustrate the fundamental difference between pulling equipment and lifting equipment, and the need to keep their functions separate. All usernames have been changed to protect the innocent.

(The missing Cripes no.3 needs to be inserted where the character aliasing as PWSlack discovers that three colleagues have become hurt and their families need to be advised.)

http://www.offthemarkcartoons.com/cartoons/1996-08-17.gif

I reckon you could*...I'll bet the tow rope is way over rated to allow for the snatch when towing.

* Of course I wouldn't...I'd tie a load of wet paper towels together!

Somebody way back in the beginning said that is the way gravity works. What he didn't say is when you use a chain hoist vertically,gravity keeps the chain lined up with the sprockets.When you lay the chain hoist down ,the chain will bind up at most every link. A cable come along or rope block and tackle would be better. Wreckers some times use a block to double the pulling strength of their rigs by running the cable out to the load and back to the truck. But they never use chain except to make hookups on the ends of the pull.

On some chain blocks, pulling may be achieved horizontally, but some release mechanisms for them ONLY work easily or at all in a vertical situation.

eg. you might have trouble releasing it when finished pulling!!!

Chain blocks are designed only to work Vertically what you need is a couple of Tirfor's They are for horizontal pulling work really wel and can also be used for vertical lift. Your local chain and rigging store should have them or be able to get them

It may be bad practice with metal link-chains because their own weight may have better structural-efficiency working vertical, but with steel cables and bigger pulleys? why not? the Romans did it with hemp ropes, erecting A-columns for winches and bridges, adopting the Greek vertical system, and it worked fine.

What would happen if the yield stress of the weakest part of the chain block were to be exceeded while in use during a pulling operation, and what would be the risk if the same chain block were then to be used in a lift? <Asks nervously>.

Point taken.

I only thought of it in structural terms.

No offence intended.

Yeah and they mix a lot of the blood of dead slaves in the mortar when those hemp ropes broke.

I must say, we use chain blocks to pull dead hung loads into line, all the time. The technique is not utilized for over-limit dynamic loads or subject to drag friction, but rather used as breast lines or adjustments to dead loads; primarily. Such as a supplimental automated bridle leg, (or load arranging positioner, of sorts).

I completely concur with most everything you stated, as ground based friction pulling can be difficult to determine the drag co-efficient, under variable stress. Dynamic overloading causes critical failure, unless the 5:1 safety margin can be assesed with a dynamometer or load cell, and be compensated accordingly.

Most laymen will not eagerly understand or pay the extra costs, as a rule of thumb, and instead will risk the entire organisation, rather than exhibit an understanding of real threat of the mis-use of such devices. It is, afterall; Stinky Pete's responsibilty to throw the sling away, after abusing it in such fashion, unless he was not educated properly, on such procedures. "Ain't killed me yet", seems to be the underlying rule of idiocy.

Unfortunately; many times, project managers and directors get away with such equiptment abuses. They get away with pulling time and money saving stunts. Thus leading to character assasination on the person; to which these follies are blatantly obvious.

Having to emphasize physics in order to survive in the workplace can be daunting to express and impliment properly. This is especially true when faced with an underqualified or advancement minded time hungry manager. Have you read the Nasa safety report, following the wing damage failure?

I should think the Drag-Line Bucket uses such devices in both lifting and pulling functions, though. It is designed to dig until full, though. Additionally, Guy Derrecks also have been used substantially for the same purposes, sometimes dragging loades thousands of feet across cavernouse areas, from perches hundreds of feet in the air; (such as the digging of the Panama Canal).

That said, I have been to several construction sites, witnessing report, where a crane has been laid across the ground backwards. Often times, overload was acheived when conditions change, unexpectedly.

Chain blocks are not the only device used for vertically lifting. Electrical hoist do use wire. Chains are use on hand hoist and and electrical hoist. Mechanics of the hoists make it easier for the manufacture to produce something that will secure and hold a hanging load. Chain links interlock into the pulley to stop any slippage. The high gearing makes for ease of lift and holds the hanging load with out a brake.

When used vertically, the deadweight is the weight of the object being lifted. Anything which is used to pull the object sideways when lifted increases the load in the chain (or cable, or rod) above the deadweight. Using triangle of forces or the cosine rule will easily show you how much the load is increased in the chain beyond the deadweight. For instance pulling the object sideways so that the chain is at 10 degrees from the vertical increases the chain load by 1.5%. OK, not much, but increasing this to 20 or 30 degrees increases the chain load by 6 or 15% respectively, and could soon be well over the SWL (safe working load) rating of the chain block, ie lifting a 1 tonne object with a 1 tonne rated block and swinging it 30 degrees sideways increases the load in the chain by an additional 150 kg, well over the SWL rating. Explain that to the inspectors.

If you exceed the yield stress of the weakest component in a chain block system, you exceeded the SWL by a considerable factor, maybe 15 times or more. Normal engineering practice should be to work up to 75/80% of the yield stress, the designer/manufacturer will (or should, if responsible) place a design safety factor of 1.5/2/2.5, depending on design sophistication/company experience on the particular design being evolved, and the proof test load will be at least 5 times the SWL. Local laws, insurance companies, the manufacturer etc etc. will determine what cover is required.

When designing lifting beams for marine engines sometimes weighing 100 tonnes, costing £1M, I designed for a proof test load of 10 times SWL as each beam was a unique design.

Don't underestimate or trifle when dealing with lifting equiptment, no matter what the weight. It can damage reputation, costs and most importantly damage or finish life itself.

Whilst I respect what you are saying and it is undoubtedly true.

It gives the impression that dragging something sideways is always a higher load than lifting it.

This is of course nonsense as a couple of peole can push an emply skip sideways but could not possibly lift it.

Yes, I agree with you and am sorry if I gave the wrong impression. I was referring to something being pulled sideways while lifted, as said in the first few lines. The danger comes when untrained people use equiptment incorrectly because the forces required are outside the human limit and they use anything like chain blocks that might be available.

I am not a "peole"! The same to you with knobs on!!

In my experiance, when a load is under tension and the components of the chain hoist are rated to withstand a defined static / dynamic load, at the lenght of chain specified by the manufacturer of the hoist; the angle of the load is basically irrelavent, except that it may be unweildly to correct or control. Especially when hard point swivels or Fafner Bearing type swivels are included within the rigging dead point system and so long as control of motion is managed and supplimental safety systems are considered. These swivels allow for a dynamic release of energy during a shock load, such as the clevises manufactured by American, having been super rated for use for DOE.

While most agree, this may not provide permission to excede SWL for chain hoists, it ultimately improves variations of drag and lift which rutinely occure when lifting agressive and disproportional loads, such as lighting truss and speaker enclosures in stadiums. This provided opposing force can be calculated and controlled upon the diagonal force required for the side loading of the system.

Such a progressive loading may be only available at panel points where bridging and sufficient compression bracing has been designed into the supporting super-structure.

The clevises we like, excede a 5K - 25K lb. load rating, at EVERY varying angle of load from the static mounting position, in relation to the swivel, in a 170 x 360 usable degree of angle of the x/y axis and can be mounted at vertical or horizontal positions. They are rated for 5K lbs. at dead or 45 degrees of dead, static load; and safe to within 5 times that, should a dynamic occur. I see the weight of the chain as a dynamic, should it be used latterally, yet under stress, at 1000 to 4000 lbs. max.

I have yet to encounter a static use of a chain hoist which caused any noticable loss of load, by using a well maintained and tested hoist, at angles of up to 45 degrees. The hoists we use are generally rated to 140% of max lifting capacity, also. I would summise this as the reason I have been allowed such use without impediment.

While I agree, a chain hoist mounted at an angle can easiy acheive a dynamic above the load rating of a SWL dead hang, supplimental care and safety systems can be combined to limit the possibility of mechanical failure causing a compound dynamic and offering the availability of side loading or diagonal loading of truss and increase stability of load traversing systems, such as underhung overhead crane tracks and trolleys.

There are many new technologies being developed to change the methods of load management. Some of the newer designs offer exceptional safety when monitored by realtime instruments. It is important to think beyond virtical or horizontal loads, anymore. The real world is, and will continue to use diagonal pulling of massive loads to insure placement of equiptment. It should be expected, not averted at the drawing board.

Load lifting systems, including chain hoists, are fast becoming true vision systems, offering the quality of a rigging system and required documentation, monitoring and servicing of the components and the added benefit of survelance. They can include fire detection and hard wired real time load analasis, if so desired and are fully automated.

If protection from faulty use of a diagonal load has challenged the industrial sector because of the unknown potential for a diagonal load, isn't it time to impliment a strategy and design a system which can "SEE" the entire load, at all times, allowing for constant reporting of these diagonal load conditions?

Can't this type of system record incidents, should one arrise, for investigation after an accident?

Can insurance protection be acheived for complex lifting scenarios, (albeit low to medium weight projects), if such a service allows an engineer to be present and aware of the dynamics involved during such extreme lifts? (Even from his beach house, in real time?)

Are the guys and gals in the Engineering office prepared to monitor the real-time conditions of structures they have the authority over, during major events and installations, where such diagonal and latteral loading is commonly and repeatedly occuring??

Will "hard and fast rules", like some of the answers offered above, cure the mis-use or unintentional dynamic risks, taken to insure timely completeion of the project?

I don't quite think we are there, yet... Who wants all that exposure, when we can just blame Stnky Pete?

My two cents.

I do see the point about the ease of overloading, but such equipment is supposed, I thought, to be subject to regular safety inspections or tests and operated by certain individuals who have been trained in using it.

A lot can happen to equipment between regular testing sessions, particularly if it is used otherwise than for the purpose for which it is intended. To ensure a high level of confidence in lifting safety, pulling equipment (which need not be tested) and lifting equipment (which really ought to be inspected and tested regularly, and records kept) must be kept separate as regards function.

Otherwise stand well back, like 'Stinky Pete' in #10 above...

No. Unfortunately there are no such requirements, here in the USA. The ultimate risk for any major production, construction or manufacturing company is overhead risk management. The umbrella of the rigger, carries the project, in most cases. He is on his own to rent from known good serviced suppliers. There is no penalty for using broken or out of service lifting gear, until someone dies. Body harnesses or personal safety gear, yes, OSHA will inspect dated assemblies, but not the hoists.

It is O.K. to make a mistake, lose an entire rig and start a new company. Many have done it in the past and are still in business to this day. These mistakes are often purpetrated by companies who repeatedly run extreme risk without care for the safety of the employees. It is this lack of compliance with standards which has inspired the direction of my company.

For many years I have watched the standards drop and the threat of a man's job increases, for speaking about these important safety requirements. Meanwhile, wages decrease and inexperienced workers are intentionally hired to replace those in the know; who just happen to make more money and require benefits.

It seems it is cheaper to hire ignorant people than to bring the industrials to a standard which is enactualized.

Well, I've searched and searched and what I've found generally reflects what we've been discussing here. What I mean is that some of us have said that it's being done and some say it shouldn't be done.

It was a difficult to find an official document about the matter. Most of the time ,the manufacturer's manual gives the information.

Most say that their product should not be used for horizontal pulling...period. No explanations, no nothing.

A few said that their product should not be used for horizontal pulling because the chain guides and mechanisms are not designed for horizontal configuration. I guess that means that the chains could fall off the guides and damage the unit and cause it to fail or fall apart. At least that one gives a clear reason.

One said tht their product should not be used to drag objects. I'm taking that to mean that it's not allowed to be used for horizontal pulling though the word "dragging" can be misinterpreted. What if I pull it an inch or a foot? Is that dragging?

However, and here's the surprise, a few manufacturers come out and say that their product can be used for horizontal pulling!

Another point I've found is that using two hoists or chain blocks to lift a single object (that only one block cannot lift) is discouraged but may be carried out if all safety precautions have been taken and one person has agreed to take full responsibility for whatever happens.

Right in the middle of all this research, I saw a bridge being built on National Geographic where they used two cranes to lift a hug section of the bridge. I did't catch the whole commentary but I did hear that the project engineer was putting his reputation on the line by doing this.

I guess I'd have to take this up with the factory and the corporate safety officer. I haven't found anything in our safety handbooks regarding this matter.

This type of Super-lift may be safely achieved through double redundancy, safely. It cannot be safely achieved or perceived upon a barge without a stability system control; such as used for North Sea Helo pads, upon the rough ocean, where stabilizers are present.

Isn't it Tappan who manufactures the proper control units? If my mind serves me correctly, they also are used for other "high risk" purposes and employ Pheromone sensors. (D. W. Gage, "Many Robot Systems", SPAWAR web page, http://www.nosc.mil.robots/research/manyrobo/manyrobo.html.)

Why hasn't ^^^someone^^^ manufactured a "smart", load sensing, wind factored, stabilized "rental" barge for aqualtic crane pile and lifting platforms?

After what happened to Sarasota four years ago, one thought for certain someone would have developed a solution which makes the best use of "off the shelf" technology to remediate the problem. (For those un-aware, the crane was lost over the side of the barge, when wind changed and the risk which was being deemed acceptable, caused the crane to fall overboard, killing the oporator, with an 85' concrete pile swinging horizontal from the boom. The tip of the boom nearly struck the bridge, taking out the western Florida main North bound artery, as it tumbled into the ocean at rush hour, while storms were in the Gulf approaching.)

There's particularly where your calculations of load increase with 1.5% drift from plumb; comes in a bit handy... and where sudden changing conditions can mean the end of a great team of engineers and steady hands, let alone the project goals.

This may also be reason why manufacturers release themselves from indemnity during the use of equiptment, even though we all know it continues to be used in such fashion and disrepair.

In my opinion, organizing educational programs for employees under such irregularity is futile. How would a physicist react to such blatant abuse and mis-statement of scientific theory and practice, forced upon his craft? It's like throwing out logic and ordering the mind to ignore instinct or common logic or lose ones job.

Just think, the SAE was dicarded this year, officially removing chain of liability from overhead lifting, through parts manufacture identification. That means a required internal screw may be cheap pot metal, or a bushing replaced with a friction coating over less than adequate tolleranced machining, in the middle of a hoist; unless the conscious of the manufaturer deems it required. How do we teach riggers to mediate that?

One would think we may try to assertain or acheive a maintainable standard before teaching fictional delusions of safety and equiptment usage. Unless ones intention is to create a world of Stinky Pete's...

Love the part about; "As long as [someone] is responsible...", can this company be more vague? (They are effectively saying; "Just fill in your name, please"). I want that insurance rating and liability structure for my company, too.

Why bother to innovate, when loss is purely upon the fool who takes such responsibility?

Whilst chain blocks, it appears, should only be used for vertical lifting, I have used chain blocks on numerous occasions to pull horizontally and at almost any given angle and have never had any problems. Particularly pulling large diameter steam lines back into position to bolt valves into their respective locations after maintenance.

its just a design thing. the design makes it more suitable for vertical lifting ... take a look at a chain cum-along, its basic design is the same except with a handle instead of a long chain reaching all the way to the ground. And a cum-along is all position.

One has to use experience while working at remote sites. Most of the time the tools are modified to serve the purpose.

Chain block with additional pulley mounted vertically below works as puller while still acting vertical.

Based on the responses here, it doesn't sound like many of you responding have seen a variety of chain falls which allow for inverted use or have real world experience 250 feet in the air flying loads.

Please let me assure you, many models, (the vast majority of chain blocks used for temporary lifting), may be used inverted or horizontally, without the chain fouling; by using simple nylon or metal chain guides. These simple guides and chain bag management designs, easily direct the chain through the hoist, vertical, horizontal or inverted.

In my opinion, the issue is not a matter of fouling mechanically, but rather with legal acceptable use and violation there of, as stated by some manufacturers who refuse to acknowledge real world conditions.

This attitude by some manufacturers, relegates the entire liability on the rigger, who more often than not; did not choose the hoists, did not consult on the insurance rider, did not design the structure to be hung or from which will be flown, did not hire the installation team , did not train the people he or she is forced to work with, cannot be certain of the past use of the equipment and lastly cannot express any major complaints because there is no current regulation or oversight body and the time to do so may not be availble, even if there was one.

No current regulation is imposed or enforced upon the companies who supply the liabilty elusive, broken, worn and over worked equipment, (which may not be actually rated or intended for the use it has been specified for). Many of these offenders have been consolidated, so now junk gear is intermingled throughout entire international inventories, making the task of matching a set of equiptment properly, nearly impossible.

What good will mandantory education and regulation upon the rigger do, to re-mediate these inconsistencies, which stem from the insurance, manufacturers and the rental and supply companies? These are the people who are constantly cutting corners or attempting to low-ball the bid by sending used, broken or under, under-rated equipment; out of any chain of liability, in order to provide value to share holders and to support publically traded stocks.

I have witnessed repeated provision of wire rope which has been used for over ten years, show after show, with inconsistent components and major signs of abuse and wear, again and again. The latest is Chinese: steel, wire rope, shackles, ferrules, thimbles, span-sets, pear rings, axles and pulleys make for breathtaking pause. Most production labor contracts willingly allow the producer or technical director, an offficer of the company and not a rigger, exclusive right or refusal of any and all employees. This means if you complain too much about worn or broken gear, you get asked to leave and may not get called back for the overtime or further employment.

The $10.00, (supposedly), 2 ton beam clamp can be purchased from Pittsburgh Forge. How do you stop a low-ball producer or installation company from specifying such rubbish?

This equates to being forced to fly a helicopter using rotten wooden blades; instead of laminated carbon fiber over-rated units, one would expect to have available.

When common sense kicks in at 7AM and you open the box and see what has been supplied for one to work with, knowing that DEATH can occur using garbage equipment; it can be very disheartening. Worse yet, nothing happens and these players get away with the stunt, so everyones complaints appear unwarranted.

One may conclude that once the extent of the situation is fully disclosed to a responsible and competent rigger, he or she should quit or risk becoming the "problem guy" who makes it known of his or her reluctance at being offered such inefficiencies.

When the variables are not specified by the people who ultimately take the entire risk, while everyone and their brother making big money selling and renting these tools, avoids risk entirely; what can be acheived? Why should anyone be able to perform this work, basically un-insured? Riggers go to prison, if the instruments they hang kill people. Ask anyone who has litigated such a case.

The fact is, it is a credit to the people who have been performing this work at great personal risk, that fewer accidents have not occurred.

But that was back when we had SAE! It is now gone. This, in effect, means the insurance companies could care less about the human factor, because they have effectively produced enough tort to cover nearly every possible incident, (or a majority of them), which can cost them gross negligence forfeiture.

Major entertinment designers, (people who rarely are trained to know or are ultimately responsible in case of a critical event failure); often make 10-15K US, per week. Riggers... the person(s) who go to prison when a death occurs.... you don't really want to know.

A degree should not allow an individual or a company to knowingly engineer or specify a peice of junk equiptment, which has unreal or over protected liability and shall not be pressed to suit, from inception. This is far from bond rated, institional quality, re-insurance grade engineering and skirts ethical responsibility at best. This is an embarrasment and an insult to anyone with half a brain who has to work under this veil of idiocy.

By the way, this writer has worked constructing major bridges, powerplants and high-rises, for as many years as entertainment. The same disreguard is prevelent there and has been, for many years. By now, the occurance of this type of disreguard for quality is rampant.

We'll have to see how Sarbains Oxley deals with this ethics and standards transpearancy delema, under current regulation to share holders. I look foreward to seeing what protections, if any, are afforded to privately owned and self insured corporations, when there is no present method or plan to regulate against similar abuses.

Just Keeping It Real.

Can I borrow those tow ropes again, pleeeeeeeeze? I just want to help a mate pull out another tree stump. I'll make it worth your while.....

Stinky is an agent.