Chain hoist brakes failing

[Roderick]

A question that came up in a couple of rigging / safety forums recently:

Have you ever witnessed a chain hoist brake fail catastrophically?

It came up in discussions about the need and suitability of double brake hoist hoists.

 

Also raised an interesting side line:

How do you know that the first brake hasn't failed and you are actually running on your second brake thus making it a single brake hoist?

 

Caveat: I am not a rigger but interested from a risk management perspective.

[Snailtrail]

Ron Bonner from PLASA Technical Standards dept compiled a questionaire on this very subject in 2011 after the PLASA Rigging Conference. I'm sure I have seen the results published somewhere but not sure where.

 

You could try e-mailing him at ron.bonner@plasa.org

[MarkPAman]

Yes.

 

Early/mid 80s. Flown PA that had only just gone up. The sound made by the chain was enough to make sure nobody was under it by the time it hit the ground, though one of the crew ran into something & cut his leg quite badly. An empty flight case in the drop zone did not survive but probably saved the speakers.

 

If the PA had been running, we may not have heard the chain.................

[rinus]

1)

Have you ever witnessed a chain hoist brake fail catastrophically?

2)

How do you know that the first brake hasn't failed and you are actually running on your second brake thus making it a single brake hoist?

Hello Roderick,

 

[[ its a small world -

where Dutchies happen to meet (after 25 years or so?) on a UK forum! ]]

 

 

1) No.

In about 3 decades of rigging experience there was never such a brake failure.

Clutch problems did occur occansionally.

Once even when they were used, straight after returning from an "accredited certification company".

Companies are owned and emplyed by people and people come in all sorts and variations!

But 2 customers over the years were able to phone me and tell that a chain had broken!

 

The report by Ron Bonner of PLASA certainly was very informative on all of this.

I think it would take 2000 years of rigging life before such a brake failure was to be witnessed.

And a slightly shorter period even - to see a chain breaking...

( Many people mess up on brake and clutch failures anyway).

 

2)

For your information: 99,95% of all chain hoist in the world have only 1 brake.

And the double brake as required by German D8+ insurance regulations,

was unisono deemed 100% 'cow dung' by reps from CM, Verlinde and LiftKet.

Normally these guys will fight on every Euro as very very serious competitors,

and will not be willing to agree on very much at all!

 

I still wonder if that German mech. engineer from Lift Ket was not trialed and hanged for "High Treason".

 

Too few people realise that a brake in a frequency controlled system has complet other characteristics

than one that is operated in a standard single speed chain hoist.

Too much techs operating automated theatrical fly bar systems think they also know about arena rigging.

But that's only where Kinesys, Cyberhoist, Chain Master, Move Cat and fellow systems enter the scene.

 

Hope this is some kind of an answer.

[Roderick]

Hallo Rinus,

Zo zie je maar weer!

 

Thank you for your detailed answer!

 

Just to clarify, yes it was Bill Sapsis who raised the issue.

And no, I don't have a bet with him, not that silly

 

But his questions did trigger an interest and revaluing of things I had taken for granted.

So now I will have to review my recommendations when it comes to flying performers.

But that is what I love about this industry, always a challenge!

[rinus]

Bill was at the 2011 Conference where Ron Bonner did his the "breaking + brake" presentation.

I am sure I have a pdf-copy of that somewhere, if you can't get into contact with Ron.

 

If you talk flying of persons (and want to be a part Germany again) than D8+ isn't sufficient.

Then you should be at BGV-C1 level - with a lot more 'kak' required than just double brakes...

 

I have always wondered why the BGV-Insurers allowed chain hoists

with just a single chain in them for this purpose.

If anything they should have been requiring a "double chain"

as the number of chain failures was higher (I recall) than the number of brakes (/clutches).

And a chain failing is much more catastrophic than a brake or clutch failing.

I surprises me that we in this industry have been able to survive outside of the German borders.

How on Earth could we have not have killed everone without

sticking to the regulations of VBG-70 / BGV-C1 or D8-plus-Safety or D8+ or 0,5D8 or.....

what's next (SIL C and SIL 2.5?; PL 5a???)

Risk probalilities of 1 accident in 10 million or in 10 billion "switch-actions"? Or in 10 trillion??

The next comet will hit Planet Earth - but on stage it remains 100% safe!

The best lies are made with statistics and probability equasions

- as we can observe in the present economic depression caused by banking and insurance software.

Standards can specify whatever they want, one problem in our business is (as opposed to manufacturing industries)

that we will never be able to get rid of people (even if some automation jerks would want to).

In fact we should value people and the common sense they can learn what machines can not.

And:

automation is software, made by people - thus software contains bugs by definition...

Enough said!

[lorrainelambert]

How did you find that it is running on first brake....