The use of Safeties

[MartinGreen]

I read with interest the points raised on here. As a Lifting Equipment person, I can pass some sort of opinion on two main points.

 

The comment on Verlinde failures by Nick.

 

I think anyone with experience in any industry can say they have seen hoists "drop a load", or at least heard of it. I have had the "pleasure" of working directly with both Verlinde and CM to name but two hoist manufacturers.

 

In all my history with hoists (around 12 years) I am yet to see a hoist drop a load due to anything other than bad practice and/or bad maintenance. Even the cheapest chinese imports that are currently doing the rounds in general industry are VERY, VERY UNLIKELY TO DROP THE LOAD. That is unless they are taken apart by an idiot who knows nothing about the hoist, or used by an idiot who knows nothing about hoisting.

 

As for comments about the Verlinde in particular, I feel that is most unfair and typical of the industry. If a hoist is supplied with an eye or a shackle in place of a hook, that is because it has been specified like that. Otherwise the only manufacturer I know who supplies them as standard are Liftket. And your spot on Nick, its a right PITA. But correct speccing at source will solve that one.

 

I feel it is wrong in the extreme to knock any manufacturer of hoist by making such a sweeping statement. Both the CM and the Verlinde are excellent hoists in their own right and in the rest of Europe, the Stagemaker is seen in every way as the equal to the Lodestar.

 

In tests they are both equal in performance and as Chris says, you can chew the chain on a Lodestar easilly if you are trying to.

 

Having once been told by a rigger of 20 years plus that he wouldn't use a Verlinde because "they don't have a brake", I feel I have probably heard them all.

 

SPANSETS.

 

Firstly any Spanset manufactured in the UK has to have a minimum safety factor of 7:1, and in other EU countries is can go as high as 10:1.

 

Secondly, the cover of the Spanset has no loadbearing qualities whatsoever. The load is taken purely on the inner Polyester core. So a "Visual overload aid" would be a complete non starter. For instance, if there is a nick in the cover, what would happen to the overload strand? Do you scrap every sling because the cover has a nick, or the coloured load indicator has gone off?

 

There are many gimmicks out there (I know, people try to hoist them on me constantly) and most of them are just that. In my very humble opinion, there is no substitute for the correct training and proper procedures, no matter what industry you are working in. The equipment as a rule is excellent in quality most of the time, its often cutting costs or corners that causes the problems.

 

For instance, I was once working with a venue and a hoist dropped a load out the roof (best part of 500KG). Having travelled from Leeds to London, our engineer took one look at the hoist and found the maintenance record for it. The client blamed the hoist (which was in excess of 20 years old), when we analysed it, we found that it had not been serviced for 5 years and the last person who serviced it left one of the bearings on the load wheel out. At what point is this the fault of the hoist manufacturer? To me, this sums my concerns up in a nutshell. Why invest thousands of pounds on quality equipment (no matter what flavour you desire), then ruin it by not having it serviced?

[Nick Evans]

Rescue: I am trained and often provide rescue training. You're right, but delay = bad news, you have to balance need against risk. 

Unconscious person = rapid rescue (irrespective of other injury). 

Secondary suspensions or a set on stage = delay. 

Powered access probably always best (but if the is a MEWP on site, why is someone climbing on a truss?)

How do you rescue a suspended unconscious casualty when there is no mechanical access? How can you tell (from the ground) whether an unconscious person is breathing? If a casualty is conscious but bleeding, how badly and from where? What do you do if they pass out after you have decided to delay rescue? What if the casualty has fallen and is being strangled? What if they are panicking and to approach them is dangerous and they are in the mean time injuring themselves further? How do you assess the risk (from the ground) before deciding to delay any rescue? I am struggling to see a circumstance when it would be advantageous to delay rescuing a suspended casualty .

When you say rapid rescue, what does this mean, by any means possible? To me, rapid would mean breathing and circulation must be restored, either artificially or by the casualty recovering, within 4 minutes. Unless the rescuer is already aloft, I find it difficult to believe that rescue is achievable in that time unless a) powered access is immediately available or b) you bring the truss in.

 

(but if the is a MEWP on site, why is someone climbing on a truss?)

The seats are in, the barricade is built, the stage has rolled, there is no room for it in the building and it must be stored outside..... etc.

 

Secondary suspensions would be best made as a basket and shortened with a clutch chain. 

In my brief research since your last post, both the major rigging companies in the UK regularly send out 

clutches/STAC for precisely that purpose.

As I said, I have never seen rigging for a tour with enough chains to do that.

 

With respect, just because you have no first hand knowledge of something doesn't mean it doesn't exist or can't happen.

I know of no occasion in the entertainment industry where a hoist or the associated rigging failed after the load had been trimmed. If an example could be provided then obviously I would have to withdraw this element of my argument.

 

BTW, who is 'we' in q. ''why we use steels...''?

Riggers. Riggers use steels to fix to beams. Given the choice, on any I beam, a bit of burlap and SWR basket. Please don't tell me that is wrong as well.

 

Safety measures are a balance of severity and probability, actually. The law requires measures taken to be proportionate to risk, not the perceived risk.

And my point is, if a system is sufficiently reliable it needs no redundancy.

 

Don't get what you were saying about soft eyes?

I was told, by two people who made and designed SWR assemblies for two different companies, (Bridon Ropes and Rope and Marine Services) that the safe working load of a steel is the same whether or no it has a thimble. The thimble is there to prevent wear over time (and hence make the steel last longer). The only time I have regularly used them is rigging through the small downstage holes in the roof at RAH, where a hard eye would not go through the hole.

 

Roll on the National Rigging Certificate

I agree, actually I am all in favour of proper training so long as it is relevant. When I first started, I contacted IRATA and asked them about climbing courses, it was so long ago they told me they were not interested. They were more interested in people on oil rigs and transmission masts. The next time I heard about them was in The Dome, about 12 years later. I hope that the syllabus of such training will not be telling me that everything I have done and learned in the last 17 years has been dangerous and outmoded, and there is a much better way of doing it which takes twice as long and offers only a theoretical benefit (don't get me wrong, I have nothing against theory, being in the middle of an 8 month course and having recently completed a four year period of study). I am (genuinely) interested in such a scheme and would appreciate someone letting me know how I can apply for training. One tiny worry I might have is how does the self employed person who has been rigging for donkeys ears present documented proof of such experience. I am presuming by the sentiments expressed here that current practice within the touring environment is outmoded and out dated, and therefore of no relevance to any future qualification, rather like the drunk driver, I need to have the bad habits trained away. And sadly it will all be for nought if employers, promotors and production managers do not realise the benefit of such a qualification. (No, this is not what I want to see.)

 

Martin

I think anyone with experience in any industry can say they have seen hoists "drop a load", or at least heard of it. I have had the "pleasure" of working directly with both Verlinde and CM to name but two hoist manufacturers.

Please read the post, it referred to an older series of motor which as far as I am aware is not in production. Furthermore I went on to say that I am not familiar with the current Verlinde range and I was referring to an old range of motors. The 54/104/108/204 range was designed for a different purpose than the one it was put to in the entertainmnet industry.

I feel that is most unfair and typical of the industry

Perhaps there is a marketing question here, what is being done to change this perception?

 

EMJ you are correct chocking reduces the life of the steel, just as in the case of the soft eyed steel. You are also correct about it reducing the SWL, but this is also true for spansets, which are similarly derated to 66% of SWL by choking.

[MartinGreen]

Please read the post, it referred to an older series of motor which as far as I am aware is not in production. Furthermore I went on to say that I am not familiar with the current Verlinde range and I was referring to an old range of motors. The 54/104/108/204 range was designed for a different purpose than the one it was put to in the entertainment industry.

 

Nick, it wasn't meant as a swipe, and I read the post fully. You are referring I assume to what is known in the industry as the L104 or V104. I know it well. A good hoist that is now showing its age. However, it will only drop a load if it is badly maintained or used. In all my days in lifting, I have never seen a hoist drop its load due to a manufacturers fault. Doesn't mean it hasn't happened, just my personal experience.

 

Historically, all hoists were initially made for general industry (where it has 96% of the market share) and secondarily for entertainment industry. The Lodestar was first made in the 50's as an industrial hoist. Whilst it has changed from its original incarnation (thank god), it is still in essence the same unit that churned out of the good old US in the 50's.

 

The Litachain (L104/L108 you were talking about) was predominantly an industrial hoist as you rightly say. However as is typical, someone saw the market, the industry liked the hoist and away it went. It is indeed an outdated hoist with its oil leaks and its older technology, but hoist technology hasn't really changed much in 50 years. The principles are identical to what they were back then. Motor, gearbox and brake.

 

Marketing? As a marketing/sales person I read your point with interest. I don't actually blame anyone for having the point of view that they have regarding Verlindes and Lodestars. CM have the UK market leading hoist and the likes of Tomcat and LTM run excellent training courses to back that up. Verlindes marketing is at best poor. As someone who has had face to face meetings with them on exactly that matter, I can tell you first hand, they are a difficult company to talk to. But their product has its place. In my opinion it is so much quieter than any other hoist it is perfect for installations and theatres. However, in a touring environment, I would prefer a "bombproof" Lodestar. I would say in my own opinion that the Stagemaker is actually a technically superior product, but as you rightly say, marketing rules here and the CM marketing machine is far better than that of the french. Perhaps I can show your point to the Product manager of Verlinde next time I meet with him. He always tells me that the British market is a mystery to him!!!!

 

I read part of your last post and you make a very good point. Again, I can only refer you to my experience in Lifting, but your "donkeys ears" of work are not and should not be regarded as dated and outmoded. Indeed the very essence of what you have seen and done over the years makes it essential that your experience is not wasted in my opinion.

 

Industrial Lifting has something called "competent person". There is no set qualification to be one of these, although I hazard a guess that in a court of law its a bloody good idea to have something to back you up. Your experience in your given industry is what indeed makes you competent.

 

As such, if you go on a motor school and have relevant training coupled with the right experience, you can class yourself as a hoist repairer. Its what every hoist repairer (good ones) I know have done. They have then gone on to sit the LEEA (Lifting Equipment Engineers Association) qualifications in their chosen field.

 

For example, I know chain inspectors who have been inspecting chain for 20 or so years, but they don't have a single qualification to their name. This doesn't mean they are useless and outmoded. Their experience makes them what they are. However I think anyone in the current climate would be foolish to turn qualifications away where they are relevant to the job you do.

 

As I say, this is the way it has worked for years in traditional lifting equipment. However, I am certain Chris Higgs can give a more in depth answer with regards to specific qualifications within the rigging industry as that is his forte.

 

Added Quote tags - Bryson

[Chris Higgs]

The proposed certificate is an assessment, not training.

We were most concerned to make the certificate available to all, since many of us have no qualifications, only experience. You will hopefully be able to buy the syllabus and study yourself if you wish.

Evidence of experience can be documented; many bodies apparently use this method.

 

PLASA was chosen to administer the scheme by the main 'players' in the rigging trade in Sept. 2004.

 

I don't discuss training here for obvious reasons, but if you're interested, Nick, PM for phone number, or Google it/me.

 

Re soft eyes: yes, I know. What I didn't understand is why you mentioned it.

Re redundancy, yes, obviously. However, if the hoist is not designed to be used overhead (and few are) you must take ''extra precautions".

Rescue-wise, all you suggest should be part of risk assessment and be acted on accordingly. The risk is probably actually quite low, but the severity very high.

If the hazards are well controlled, most of your examples are unlikely to occur. Trouble is, we often accept risks we shouldn't. There are many methods of work traditionally unchallenged that need to be, technically, legally and morally. When things are discovered, it often means dearly held views are in question.

[andy_s]

and for examples of the high standards in this industry, see the Spring 2005 edition of "Sightlines" for video stills of a named (and prosecuted) individual working in a supervisory capacity doing something silly. Hopefully his approach to supervising consisted of the "do as I say, not as I do" type. According to the report, the rigger and URL both pleaded guilty and were fined.

[Pete McCrea]

Trouble is, we often accept risks we shouldn't. There are many methods of work traditionally unchallenged that need to be, technically, legally and morally. When things are discovered, it often means dearly held views are in question.

 

Agree fully. And oh how hard it can be to get these views changed to represent something is better on all fronts

[Nick Evans]

Soft eyes were mentioned because dtgordon had concerns about choked steels and what happens to them.

 

All of the scenarios mentioned regarding a fall from a truss were in regard to delaying the rescue of a suspended casualty. I have never had to deal with a suspended casualty, however the only circumstance under which I would even consider delaying rescue would be if the casualty was talking lucidly and taking active steps to rescue themselves. Under all other circumstances I believe rescue should be attempted without delay. I would certainly look long and hard at any colleagues who did not immeadeatly attend to me if I were ever to fall. Even if someone managed to fall clear of any obstructions and was entirely unharmed there is a high chance they will go into shock following a fall.

There are many methods of work traditionally unchallenged that need to be, technically, legally and morally.

I would contend that safeties on trusses etc are one of these. safeties originated as a requirement of licensing authorities, not riggers. The practice is one which has been passed on between authorities, not something that tour riggers automatically carry out. One of the first questions asked every morning of local riggers on a european tour is what safeties do we need to put on ie what safeties does the local licensing authority want to see. This might be PA only, or everything downstage of the barricade, or everything downstage of the downstage edge (ie everything over the pit as well as the audience or, some authorities require everything to be safetied. I am probably looking at this from the wrong perspective, but I never said to myself, "I think I will put safeties on that, just in case the rigging or the motor fails". If there was any doubt in my mind, I would do something different or not do it at all.

I am still unaware of any incident where a motor or associated top rigging has failed when a flown structure has been at trim.

[Guest lightnix]

Trouble is, we often accept risks we shouldn't. There are many methods of work traditionally unchallenged that need to be, technically, legally and morally. When things are discovered, it often means dearly held views are in question.

Agree fully. And oh how hard it can be to get these views changed to represent something is better on all fronts

<{POST_SNAPBACK}>

Ain't it the truth? I remember having my sexuality questioned for suggesting the use of harnesses back in the 80s.

 

I know I've said this before, but I still think a good way forward would be for independent training providers to start working more closely with the colleges, to incorporate things like electrical and rigging training into existing courses, at a basic level for everybody and an advanced one for those who wish to pursue those disciplines as careers. Surely it's much easier to train newer people into good habits, than older people out of bad ones.

 

Could be a nice, regular earner, too

[Chris Higgs]

Since we all seem to be singing the same song in essence and I'm away again, I'm going to leave this one alone now and make this my last post in this thread.

 

With regard to rescue, any fall must be treated as potentially dangerous.

Even without a fall, prolonged suspension is potentially fatal, - no need to go over harness/suspension intolerance again? 15 minutes to removal from suspension is the target time, sooner if possible. There is every reason to suppose that after 30 mins or less, but almost certainly within an hour, you would fall unconscious in any case. Then your survival time may be as little as 10 minutes.

So what better reason to avoid the need to climb using PPE - use an appropriate means of access at least some of the time - it's reducing the risk dramatically.

"Well, how are we supposed to focus, then?" There are lots of alternatives, and growing in number every day, most of them time consuming and expensive BUT compared to the consequences of a fall, highly affordable and entirely do-able.

Eliminate the hazard wherever possible.

If you really need to climb, (and there will be times when it is justifiable, and not just on trusses, either) there must be sufficient trained people (2 or more) on hand with the necessary kit and training to effect a rescue. It's the law.

May be a 'snatch' rope rescue, maybe not. But if it happens, you need to be ready to do it with little or no warning. We recommend a formal drill at least every 3 months to venue staff/companies, in other words all concerned get 4 practices in a year.

 

In closing I would say that there have been failures where a decent secondary would have been a salvation, thankfully not where life was actually threatened, but still 'near misses' (so "reportable" incidents, too).

I won't be naming and shaming, though, unfair and uncool.

 

When people say "I've never seen a hook clamp bolt fail, so why do I need a safety bond" it strikes me the same way. Just because one has no personal contact with an event, it doesn't mean it hasn't happened or won't happen.

The bolt won't fail, no, but two bars crashing can (and has) stripped every lantern off the bar by shearing the trunnion.

Moving stuff can contact static stuff, static stuff can get overloaded by other stuff being rigged on it later. People can clamber about on static stuff, supporting structures can shift, and that's before we start thinking about outdoors.

I understand the reluctance to accept it because of the apparently low incidence, but it isn't an unreasonable requirement, surely?

I believe that currently around 25% of all reported accidents involving lifting equipment in all sectors are the direct result of equipment failing, it doesn't seem important to me at what point in the lifting cycle it occurs.

There are companies renting lifting equipment and accessories that don't have an inspection regime. How do you know that a hoist is 99.9%? You should be provided with a report of inspection by the supplier or demand to see one before you rig it, stand under it (when static, yes...) or trust your weight to it, but even then, it's only a piece of paper raised maybe six months or a year ago.

Surely the point is that using a secondary or some similar appropriate means is precisely because it affords an extra degree of security for the unforeseen.

 

For a permanent installation, or one where components have been tested off site, then you may not need a secondary at all; the new Standard and the yellow book would support that decision.

But for temporary overhead suspension with a machine (specifically excluded for overhead use without secondary measures by the manufacturer) you do need to take extra precautions, LOLER says so, so does the new Standard and the yellow book, too. If a truss is picked up on just two motors, then clearly the consequences could be very serious.

Legislation requires measures to be reasonably practicable and in proportion to the risk. Using a secondary or appropriate redundancy in suspensions, well rigged and planned for, is both reasonable and practicable and not out of proportion when the worst case is considered.

[Nick Evans]

Since we all seem to be singing the same song

I certainly am not, or I have been reading a different thread. It is my contention that safeties are an unneccasary requirement which can endanger the people putting them on (extended duty time) and people on trusses (who, if there is no mechanical access available, cannot be rescued before they are dead) I have continuously stated this. I was told that I was making excuses and that such thought was probably the product of learning bad habits and working practices, and sticking to them, rather than accepting the views of others. I have tried to defend my initial views with reasoned argument and posed questions, which have been evaded. I have no wish to withdraw from a discussion where my opinion and professionalism have been questioned. I post here under my real name.

 

With regard to rescue, any fall must be treated as potentially dangerous.

So under what circumstances would you delay a rescue?

15 minutes to removal from suspension is the target time, sooner if possible.

Whose target time? Certainly not of the unconscious guy dangling on a rope. If he is not breathing he WILL be dead in 15 minutes.

"Well, how are we supposed to focus, then?"

Moving lights and automated focussing systems are great, but how do you fix them? As more and more automation gets put in the air focussing lights becomes only one reason why people will have to climb. Tab tracks, winches, kabukis, video walls and whatever else all require close personal maintenance.

compared to the consequences of a fall,

The consequences of a fall are not automatically fatal or life threatening, a lack of prompt rescue is.

I've never seen a hook clamp bolt fail, so why do I need a safety bond

I have seen plenty of examples of bolts being the wrong size, stripped, the wrong length etc. The hook clamp bolt is not subject to regular load testing and is probably only noticed at all when it is not present. All lights should have safeties, they are often called into use. Not having a safety is reason enough not to hang the light (or accessory e.g. colour changers, barn doors, wobbly mirror bit).

I believe that currently around 25% of all reported accidents involving lifting equipment in all sectors are the direct result of equipment failing, it doesn't seem important to me at what point in the lifting cycle it occurs.

It does when discussing whether or not secondaries serve any valid purpose. If failure occurred when the load was moving safeties would serve no purpose unless they changed length as the load moved (inertias on every point, anyone?) Where are these figures coming from, the construction industry? If it is, what relevance does the construction industry have to entertainment? Construction, where the most common form of lifting equipment (the crane) has no secondary method of suspension.

There are companies renting lifting equipment and accessories that don't have an inspection regime.

In the entertainment industry? I don't think so. I am fairly sure this would be illegal. If I had any doubts at all I would want to see certificates, and if there were none they can get someone else to hang it.

Surely the point is that using a secondary or some similar appropriate means is precisely because it affords an extra degree of security for the unforeseen.

But where does the inclusion of redundancy end? Above I have set out a very good reason for why all lights should have safety bonds, because of the lack of inspection of the hardware. What about truss bolts and pins? Where is the redundancy in a pinned truss joint. Should one of the lower pins fail, the load on the other pin will immeadeatly double. Should we be exploring other methods of joining trusses? (If not, why not).

For a permanent installation, or one where components have been tested off site, then you may not need a secondary at all;

The longer the exposure period, the lower the risk??? I would love to see the mathematics behind that.

 

As far as I am concerned, safeties are a requirement of licensing authorities, not riggers.

[Pete McCrea]

Where is the redundancy in a pinned truss joint. Should one of the lower pins fail, the load on the other pin will immeadeatly double. Should we be exploring other methods of joining trusses? (If not, why not).

 

Surely in the safety factor designed in by the Structural Enginneer at the point of design?

 

Directly quoting from the sheet that comes with the CM Lodestars (well the ones we have in hire stock):

 

4)"In theatrical use, the load should always be tied off with auxillary chains or cables before access to the area beneath the hoist is permitted. As an alternative the system maybe designed such that the malfunction or failure of one hoist's load bearing components does not cause load loss and/or overloading of any other hoist(s) in the system. Note that in such a system individual hoist performance and function must be monitored visually or with the use of load cells"

 

and:

"Do secure load after positioning by using auxillary cables and chains"

 

"Do not leave unsecured load over people"

 

"Do not lift people or allow people on unsecured load"

[Nick Evans]

Surely in the safety factor designed in by the Structural Enginneer at the point of design?

I doubt whether any trussing system has ever been designed with the possibility of surviving a pin failing. Triangular truss with only 2 pins is just ladder beam, it will be subject to bending in the horizontal plane. Will it fail, I don't know, it depends on load and length of span. Square truss will do slightly better, as the top pins will help to maintain the structures "shape", and actual it become a triangular truss so the upper chord above the failed one goes from compression to tension. But the point is, if it can fail, should there be a redundant system to account for the possibility of structural collapse. I say no, because the chance is too remote and the consequences are not always hazardous.

 

I do not know what theatrical use as opposed to any other use, but I have a strong suspicion that product liability laws in America, being what they are, manufacturers are obliged to warn users about potential failures and using safeties, much like the "caution, the beverage you are about to enjoy is hot" on coffee cups. I would love to know how many Lodestars have failed in the last 20 years....

 

"Do not lift people or allow people on unsecured load"

I have to say, for reasons of safety (and I know I am going to get crucified for this) on large grids with multiple motors I prefer there to be someone on the load as it comes down. They are listening for motors stopping and watching the load as it changes shape (and it will) to prevent points being overloaded. Normally I would bring down large grids in stages, maybe 4 metres at a time, stop, assess how the load is behaving, pick up any points which appear to be under lifting, then go for another 4 metre move. Now, that is contrary to the manufacturers recommended practice, so I do not ask anyone to do it, I do it myself. When 30 or 40 motors are running it will be virtually impossible to spot a stopped motor straight away, and it may only take 2 or 3 seconds before a point is overloaded. One day we will have intelligent motors with built-in dynomometers and signalling systems that will shut controllers down I am sure, but I am fairly sure also that we are a long way from a reliable system rugged enough to be toured and maintain its calibration.

[dtgorton]

But the point is, if it can fail, should there be a redundant system to account for the possibility of structural collapse. I say no, because the chance is too remote and the consequences are not always hazardous.

 

You know, it sounds like you're weighing up the likelihood of things going awry in a Risk Assessment stylee. I would agree with you on this, by saying that anything is possible, but not everything is probable. However, one does one's Risk Assessment to examine all reasonable risks and then lists all reasonably practicable control measures, with a side order of residual risk for good measure. So I'd look at a rigging assembly and think, amongst other things, where the structure could be reasonably foreseen to fail.

 

From top down, a rigger has to trust what the venue say to him/her via the Struct Engs, so to place the top steel. You make your points on nice sturdy bits of roof or rigging superstructure, if it looks a bit dodgy you don't do it, or you get the competent person over to verify. Each piece of top rigging is from LOLER-compliant stock, right? It is additionally checked as it is assembled into the top bridle(s). You know the drill; lose anything that looks vaguely sus and get it checked out in the warehouse later on.

 

From the bottom up, the truss is checked out, as are the pickups (fibre roundsling anyone?) and all components of the pickup assembly. A competent person checks all the pins are in place etc.

 

The only missing bit in between is the motor / lifting apparatus. This is the only bit of rigging kit in the lifting assembly that one cannot make a useful and accurate assessment of on site, in place, as it is a sealed unit. We know, or suspect, it is also a complicated piece of machinery, containing several moving parts, plus control mechs etc. Therefore, in weighing up what could be reasonably foreseen as a reasonable risk of failure, I think it is entirely reasonable to safety this part off. I mean, what's the problem?? A rigger's compentency is rigging (natch), therefore I believe the additional hazards posed by adding additional rigging (carried out by the competent persons) are far outweighed by the additional safety margin given to the public / artiste / working crews and allowed by a safetied-off truss.

 

A personal note too on safeties; I have been brought up in the way of motor bypass rather than full bypass. The reasoning behind this is again down to reasonable judgement; is it more likely the chain / hook will fail on a hoist or a part of the internal mechanism? Anyone want to pick that up?

 

A lot has been made of reaching an unconscious, unbreathing, elevated, & remote casualty within 3 minutes. Not wanting to make light of any such situation, I am struggling to picture a scenario where this outcome could be reasonably foreseen (so that control measures could be put in place). In any situation when someone has taken a fall, the last thing I'd want to do (admittedly not having been rescue trained) would be to run in the truss they were hanging from, especially if it were a large, complex lift in the first place. Surely the onus is on getting to the casualty, not bringing the casualty to you or potentially making the situation worse by moving something? In the past I have worked where it was deemed there should always be a 2nd method of rescue available, usually a 'picker, and I'm pretty sure that any such casualty could be reached quickly, if not always within 3mins.

 

In short then, as this is a massively rambling post;

1) we do our RA to weigh up hazards, severity & probabilities

2) it seems reasonable to me to safety off complex components that we cannot verify for ourselves

3) I wouldn't move trusses with unconscious people on them

 

(An aside to the Moderators: perhaps we should pack up our arguments & move all this into a new thread re motor safeties??)

 

Just on the truss failing thing: I have personally experienced a good old span of small-gauge triangular-section truss fail when lifting through contact with another bit of truss. The pins, without exception, all held good. The truss ended up "failing" at the welds of the lugs. I cannot comprehend a pin failing other than by someone not putting it in place & securing with the R-clip. But hey, that's why we've got crew chiefs & other responsible people around to check other people's work before carrying out the lift...

[Chris Higgs]

The lure of the fray was too much!

 

Nick, I always post under my real name, too. I am not questioning your professionalism (whatever that is) but your views that the way things are done are the only way. (Perhaps you didn't mean me)

We need to advance our ideas; interesting when someone asked about slings with telltales. Yes, they do exist.

There are inertia reels in use in many places to speed up load in/out.

There are systems with slack chain detection, loadcells and so on already available and in use, though the ruggedness is a valid point. The new Flashlight/Vertigo/Cyberhoist system may be the way forward.

 

There are companies who have NO inspection regime for trusses, Nick, trust me, I earn part of my living by trying to help them out of the poo.

There was even one company a few years ago who hadn't had any rental hoists inspected or tested in a very long time indeed, some reports suggest ever.

I am not evading any issues whatsoever, but I refuse to name names here, I wouldn't like it and I won't do it to them. In my position I am very lucky to be able to enjoy the responsibility of being involved with helping people improve their systems (I hope) and I feel bound by an amount of client confidentiality.

As offered, contact me and talk about it directly.

 

I wouldn't 'crucify' you about riding a large system, personally. If there is no other, safer means of getting up/down and no-one is exposed to being stranded or crushed in the process and they can be rescued. It was standard practice in the 80's and I'm sure it is still quite do-able. Which is safer, a wire rope ladder climb or sitting on a 50 motor truss grid?

 

15 minutes is the time typically quoted to prevent the onset of orthostatic hypotension (harness trauma). That's if you are uninjured but unconscious.

Of course if there are other conditions prevailing you need to take account of that, but this isn't a training course.

I have been working with one guy who had a fall and suffered sever spinal injuries.

When his mates crowded round, eager to prevent him from moving or being moved, heard him say "I can't breathe" - tough call, but what to do???

Unconscious people or injured people can most certainly be rescued by 'rope' in many ways from the truss, probably quicker than any other way, and especially if safeties are in place.

The provisos are that there is the skill and kit to hand, the truss is undamaged and no-one is putting themselves at risk in undertaking the rescue.

In Earls Court a few years ago, we were getting people off the mother grid in this way in under 10 minutes. Taking the deads off takes a lot longer and there may not be a machine in the house. (You want to comment on that Dave G?)

 

My comment about the bolts was in quotes. I am not saying that, I've seen it happen, but that is what some folks seem to believe.

 

The motor bypass issue is interesting. Both the big players say "don't" use the clutch technique. They are concerned about the damage to the chain or the security of the clutch on the chain.

Many of the accidents we know of involved chain/hook connections or load displacement, not the hoist innards, so the clutch method may not actually do much in any case.

Likewise the double brake issue - safer how, exactly?

If it's to be done, a separate independent secondary is surely the best way.

 

Incidentally, AFAIK all the hoist manufacturers say don't leave loads unsecured (or words to that effect), not just the American ones, Verlinde, Liftket, Gis, Donati, Hitachi for example. They have to, because they are obliged to 'inform' as part of their duties in putting hoists on the market.

 

In terms of manufacturers accepted practice, I suggest that moving in short steps and re-assessing load and level is exactly what all truss manufacturers say and it helps the duty cycle of the hoist motor.

 

The comment about "longer exposure, less risk" : the point about the Standard and the yellow book is that for a permanent installation you will have 'engineered out' the risk by increasing safety factors, redundancy, etc. thus a secondary should not be necessary.

Is it me not saying what I mean?

[Nick Evans]

We need to advance our ideas

And yet when it is suggested that safeties add no value to the safety case and may in fact be a casual factor in incidents and furthermore endanger people, the idea is dismissed.

There are companies who have NO inspection regime for trusses, Nick,

What was originally said was

There are companies renting lifting equipment and accessories that don't have an inspection regime.

I see a difference between trusses and lifting equipment, which I take to be the equipment doing the lifting ie motors and steels. The distinction is important because the thrust of my original statement

Many venues will insist that trusses picked up with a spanset have a steel secondary between the truss and the motor, though more and more the safety will go straight to the roof, bypassing the motor as well (pointless dangerous exercise IMHO)

was that the chances of a motor or associated rigging failing are so remote that the associated extra risk of applying safeties is not justified. This was described as

Sounds like an excuse to me.

I suspect that this comes from the same school as pulling up steels and wrapping them around beam or truss until they are 'tight' and choking them back with a shackle?

Copying what you see rather than learning the trade.

Which I did not take to be complementary.

There was even one company a few years ago who hadn't had any rental hoists inspected or tested in a very long time indeed, some reports suggest ever.

It would have been very difficult for them to have done any gig that required a licence I think.

There are inertia reels in use in many places to speed up load in/out.

But I say they are impratical for touring. The number of points to be pulled up doubles, for a 2 ton point eg a PA point you need an inertia capable of arresting a 2 ton load, and the associated rigging. I do not have the paperwork to hand but I suggest that in order to stop a 2 ton dynamic load you need more than 13mm steel.

My comment about the bolts was in quotes. I am not saying that, I've seen it happen, but that is what some folks seem to believe.

I realise that, and I agree with your line of reasoning, however would you apply the same line of reasoning to a truss bolt?

 

I would not expect and would actively object to naming and shaming, it rarely serves any purpose. What I meant by evading questions were such things as how do you restore the breathing of a non breathing unconscious casualty in 4 minutes. dtgordon mentioned that there had been a lot made of the need to rescue a casualty withing 4 minutes. A friend was walking on a truss (it was along time ago) which was 4' of the ground. She tripped on a cable and fell. As she fell she struck the truss and landed half on half off, with the brunt of the impact taken by her chest. She was helped down (it was only 4' after all). A minute later she became dizzy and lost consciousness. She did not need to bang her head, she just needed a heavy fall which did not even leave her under the truss. If she had been at height she would have needed rescue. Without positive indication that her breathing and circulation were fuctioning (difficult from the ground) it would have to be assumed that she had neither. She would therefore require attention within 4 minutes.

 

The example of Earls Court is an interesting one. It was my understanding (I am sure someone will be able to put me straight) that the mother grid had to be deaded off before the load could be applied, so that before trusses were run up the mother grid chains were slack and the load was on the deads (it may have changed, I have not been in there for years thank god) Hence, once the mother grid has been trimmed, why does anyone need to go up there? Oh, to put the PA safeties on. The same is true of Wembley Arena, where there is no mechanical access, and no way of getting any mechanical access downstage once the stage is built. (it may also have a reduced floor loading but I am not sure)

 

I agree with dtgordon that there may be hazards involved in moving large grids in order to rescue someone, the larger the grid the less likely it is to be practical because of other obstructions etc. HOWEVER, most tours have many individual trusses, and on many occassions all that needs to be dealt with is the cable going up to the truss, which means that when someone is in danger, all that has to happen is the motors get bumped through and then run in. The casualty is less likely to be disturbed by the truss moving than rescuers climbing along the truss, especially if it is a straight truss.

In short then, as this is a massively rambling post;

1) we do our RA to weigh up hazards, severity & probabilities

2) it seems reasonable to me to safety off complex components that we cannot verify for ourselves

3) I wouldn't move trusses with unconscious people on them

1) based on what data?

2) If data supported the contention the device was extremely unlikely to fail this becomes uneccasary and does not allow for the implied risks incurred by using safeties

3) I would if it was the most practical way of rescuing someone. I would also expect my colleagues to do so if I was the unfortunate.

I have been brought up in the way of motor bypass rather than full bypass.

In the words of Yoda, "Do, or do not". Using a clutch like this is using it for a purpose for which it not designed, likewise the chain is designed to accept loads in certain ways. I am not saying it does not work, but the only occasion I have ever heard of a motor catastrophically failing is when the hook and chain parted company (The truss was moving, there were bolts missing from the hook i.e. it had not been inspected beforehand. It happened a very long time ago (15 years I think)).

dtgordons point about having seen a truss fail through being struck by another truss. I know this was posted in order to demonstrate how truss fails but the actual incident took place because of human error, someone was not watching the moving load. Human error is exactly what I am talking about when trusses and other structures are run down onto safeties. It happens more often than you think and is potentially very dangerous, as I have outlined previously.

I agree that we have strayed a long way from topic, who wants to set up our new home?