Does anyone have a video of a runaway batten/arbor?

Crazy question, can anyone point me to a video link showing a runaway batten or arbor; to use as a part of my school safety lesson. I thought maybe when someone had an older flyrail taken out that they might have taken the chance to make a teaching/educational video. Somewhat like when firefighters train on burning an old house that was to be torn down.

I'm not expecting that anyone would be videotaping a catastrophe!

Thanks if you can help!

That tape would be an excellent sales tool for a motorized rigging manufactuter

Not sure where you could get a video of it. But I do have the vivid memory of one and if you want to pay for me to come in as a guest speaker I'll tell my story and maybe the look on my face will be enough to convince people it's a serious event.


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For my training this week we did a simulated runaway with a Tennis Ball from the grid. We went over safety postions to goto if a runaway happens and then assigned crews to multiple places onstage and had them begin tasks. For the runaway drill, we watied for them to get started on tasks, called runaway, waited for 3 seconds and then dropped the ball from the grid. When the ball hit. We called FREEZE. Students and staff were able to see where they ended up. It was a good reality check for time involved in runaway situtation.

That's really clever, Chris! I can imagine that many were surprised with how little time 9.8 m/s/s of acceleration affords one to take cover.

Moose Hatrack said:

That tape would be an excellent sales tool for a motorized rigging manufactuter

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I saw the sales ad for the automatic braking system; it is much like those used on the four corners of elevators - something like the cord catch that mini blinds in the house use.

Chris Chapman said:

For my training this week we did a simulated runaway with a Tennis Ball from the grid. We went over safety postions to goto if a runaway happens and then assigned crews to multiple places onstage and had them begin tasks. For the runaway drill, we watied for them to get started on tasks, called runaway, waited for 3 seconds and then dropped the ball from the grid. When the ball hit. We called FREEZE. Students and staff were able to see where they ended up. It was a good reality check for time involved in runaway situtation.

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That is an excellent idea! Great suggestion and good plan! Thanks!

Not an answer to OP's question, but it is something I do with my students to give them an idea of the hazards of out of balance conditions. Using scrap and a few pulleys I bought at Harbor Freight, I built this-



I used a junction box for the arbor and a PVC pipe for the batten. The "scenery" is a 1/4" steel plate and the counterweight is a length of G30 chain. The lift lines are just clothesline I had in the shop and the purchase line is some polybraid stuff I had lying around. All the pulleys are pretty cheap, so if you replicate it I'd recommend possibly upgrading the blocks, but otherwise it works just like you'd expect. We can show what happens when you untie the set piece on the deck (boom) and also what happens if you unload the arbor at the bottom (also boom). It also helps the kids visually see how the system works on a small scale which I've found helps them understand the big system better.

Now, if you could get that to runaway and "teeter-totter" a couple times, that would be amazing.

Not sure what the teeter totter is in this scenario? I've heard that if an arbor heavy line set runs away, when the arbor hits the bottom it can bend/deform and shed its weights (assuming spreader plates aren't used), creating a pipe heavy line set that runs away again in the opposite direction. Is this what you're talking about?

bobgaggle said:

Not sure what the teeter totter is in this scenario? I've heard that if an arbor heavy line set runs away, when the arbor hits the bottom it can bend/deform and shed its weights (assuming spreader plates aren't used), creating a pipe heavy line set that runs away again in the opposite direction. Is this what you're talking about?

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If you shed some weights and then buried a curtain you could create a teeter totter type effect. Right?

TheaterEd said:

If you shed some weights and then buried a curtain you could create a teeter totter type effect. Right?

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Hmmm. That'd be difficult to replicate on this one because there's a decent drag in the system relative to the actual weight being used. It's very easy to replicate a runaway. You just hold the the part down you're unloading and then let go. Very loud bang, kids get the point when you relate that to a 56' piece of plumbing with ~500# screaming down at them.

The closest thing to the teeter totter (as TheaterEd describes, I haven't heard that term used before) would be since I use chain as ballast as you pull it out of the bucket slowly the pipe wants to run in faster and faster. Gives an idea of a purchase line slipping through the lock.

I'd like to put a curtain on it, but the weight isn't significant enough to give an idea of the forces at play, hence the steel plate. I was thinking of adding some of my son's LEGO guys to the mix.

Really Cool Strad!

Some possible additions:

Add a loading gallery and having Lego guys drop bricks on their friends down below.

The scariest thing isn't the theoretical teeter toter. It's having the arbor hit the top so hard it breaks and launches stage weights on everyone below. Take the chain counterweight out of your arbor bucket and put some Legos in instead and launch them.

Or remember that story last spring about the kid who released a line that was way out of weight and tried to stop it. He held on for a quick ride 100' up, despite hitting his head on the descending arbor. Tape a Lego guy to your handline.

Yes, that's what I meant by "teeter-totter." I made up the term. If there's a more common one, I can't remember it.

Moose Hatrack said:

That tape would be an excellent sales tool for a motorized rigging manufactuter

Click to expand...

Don't assume that it can't happen in it's own way in motorised systems!

Mine has a little 'quirk' on the varispeed bars where if you go from 'up' to 'down' without going via 'stop', both the brake and clutch disengage and the bar free falls until you e-stop the controller. Which obviously, since each of my varispeed bars weighs about half a ton, causes a horrible noise as the bar stops very suddenly, and any conventionals can say goodbye to their focus. If I had my way I'd insist it were replaced with something fit for purpose.

Not exactly a runaway set but still something to make your guys on stage aware of if you discover such a flaw in the system.

Oh MY..... does it stop at its outer/inner limits, or does it just fall to the stage floor??? I wouldn't test this, but this is certainly a accident waiting to happen. If I were you I would lockout, and stop operation ASAP, until the system is inspected. I'm guessing your insurance agent/company would not be happy about this. I'm assuming that since this is Variable Speed, it isn't counterweight assist like the Clancy Powerassist System. Also the brake and clutch leads me to believe there is some sort of dynamic braking?? Is it Vortek? This is very worrying.

It's literally free fall - so yes it would just fall to stage floor, the limits would have no effect since the load is no longer under the control of the winch drive. my theory is that the brake is off because it's running, the clutch disengages because it needs to change direction - and then nothing is holding the load anymore. It's an industrial winch system not a theatrical-purpose one so doesn't have most of the additional safety features. I have researched it myself and sadly it's an inherent flaw in the system design.

Sadly if you look at my location you will see that legislation is still in it's infancy so this doesn't break any rules. And to be honest with you, I'm not that worried. Ultimately as long as you are pressing stop between direction changes, and giving time (varispeed means accel and decel curves) for the brake to engage, it is not going to fall. So it just comes back to operator competency which was an issue with manual flying too. The system can be locked out with a key and thus only trained operators can use it.

Of course, I'd rather it wasn't this way, but I'll just go as far as saying if this was my biggest concern in the system then things would be better than they are...

Yikes. If that's NOT your biggest concern. . . I guess I'm glad this theatre is on the other side of the world from me.

Certainly it couldn't be too hard to replace the control with something that had an interlock that would prevent going from up to down.

You're preaching to the converted buddy

Let's just call it a project. Working as much on attitude as we are engineering. Sometimes you have to take small bites out of the apple first.

My electronics guru reckons he can fit a simple device so if the down button is pressed whilst the up button is engaged, it acts as a stop button.

Rather than writing you a list of what is wrong with the fly bars... think for yourself all the things that could be wrong with the fly bars, except the pulleys... and you're basically there. So far I have mostly been mitigating the risks, now I'm at a stage where eliminating them is starting to happen. You can't change a culture overnight.

Clancey just posted this video from Local 16 on their Facebook page. Not a runaway, but some incredible forces exerted after relatively short falls.

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