Chain Hoists

[Rob]

we have the motors in the roof space instead - it's neater that way, and means you don't have to take the load off all of them to work on them.

 

This also means that you don't have to worry about cable management (routing the power and control cables to a moving motor).

[Bryson]

Except we have to manage all the lighting cables that link onto the truss...but I see what you mean.

 

Actually, we have a nice neat solution these days - the socas all have a break and connection at the point where they enter the truss, so you can disconnect them all and have the truss free to fly to wherever and then reconnect the cables.

[Chris Higgs]

Chaps, you are too kind. BTW there are two books...................

 

Hire a rigger, for goodness sake, this stuff is dangerous.

I don't hang stuff up anymore, so I'm not advertising.

[daoops]

And for godsake, don't rush things and allways have in thought that this thing can fall down.

 

Just happened to me, and belive me.. that is not the way to learn why there is safety rules and certifications with theese things.

 

Think safety first, and if you feel like something is not right, then stop and go through over and over again..

[ianl]

for those of you that rig motor up, how do you attach the motor to the roof/grid/rigging point. do you use a secondary safety for the motor itself, if so , how and what?

 

I was thinking specifically of if the point (spanset?) supporting the motor failed and the truss was some way below the point at the time then this would create a large amount of momentum on its way down as well as a wrecking ball effect if it did not rip the truss out of the roof

[Bryson]

In my (permanent) installation, the motors are motor-up and the hook of the motor (VBG70 or BGV-C1 Verlinde Stagemaker SM10) is clipped directly into a beam clamp. There is no secondary suspension.

[j_b]

What if the beam clamp fails? Ianl is right - I'd hate to see that motor swing round with 10-20' of chain with - ouch!

 

...maybe, just maybe, the beam might fail? Some venues have 'temporary beams'

[SparkySteve]

this has been covered in this thread Here!, well the saftey bond bit anyway.

 

Double brake motors, for example the VBG70's like bryson's using are double breaked (if thats such a word!) and a double breaked for that reason.... as a safety measure. The argument about whether you need an extra safety bond on top of that could go on all night, but to quote bryson here.....

 

ahem!

 

 

I have 8 VBG70 (Now called BGV-C1) motors with double brakes which I'm assured do not need safeties.

 

so hopefully the argument won't go on all night....(although it might take me closer to that 1000 post mark, or even the 20,000 poster mark....hmmmm [private joke, sorry!])

 

Steve

Edit: And for the beam breaking.... even with an extra safety bond on the motor, it would usualy be to the beam (naturally depending on the circumstances etc. it may not be) so really if the beam does break, apart from a motor and truss dropping your gonna have a hell of a lot of metal and roof stuff type thingys flyin around!

[Bryson]

You have to draw the line somewhere...what if the structure of the building fails? Then we're all in big f**king trouble anyway...

 

The point is they're part of a permanent installation, load-tested and certified at the point of installation by a structural engineer, and fully inspected yearly by a Competent person. (Not a competAnt person as I keep misspelling!)

[ianl]

firstly to clarify so that we definatly dont get into that discusion again, I am not talking about possible motor failure but instead posible rigging point failure, therefore it does not matter (to my question) how many brakes the motor has.

 

thanks for the reply bryson this is what I expected most of the permanent rigs to be, however I am thinking more of semi permanent rigs or touring rigs where for aesthetic reasons it is rigged motor up.

 

so we have a motor attached to the grid (25ft above the floor) using a spanset and shackle, the motor may

a) have nothing on it

or

b) have a truss hung 10ft below the motor

 

now if the spanset snaps or melts or the shackle comes undone or fractures:

 

a) the motor falls and lands on the floor

or

b) the motor falls 20 ft, swings wildly and removes someones head or alternativly falls 20ft and the momentum breaks the truss.

 

so my revised question would be does anyone have motors rigged like this, if so do they safety the motor to the grid or did they decide it was not reasonably practical to do so or do people not do this for the reason described above

 

thanks

ian

[Chris Higgs]

The issue is all to do with redundancy in suspensions, factors of safety within the components selected (not the manufacturer's, - yours) and the engineering decisions you need to take with regard to the suitability of the structure you attaching to.

Very often you will need to employ an engineer.

With respect, you cannot get the solution to these questions from a place such as this.

If you don't know, you are unlikely to be competent to plan the work or to do it.

Use a rigging company/contractor.

[gil-galad]

Not wanting to start up the old argument again, but even if the manufacturers claim it doesn't need a safety I would always argue that adding a safety is just a part of reducing the risk as far as is practically possible. Lets face it we have all been putting safeties on for years. Why stop?

 

I remember an argument which involved the chief sound guy, myself and a local rigger up north who was refusing to put safeties in because there was no need(i.e. tooo lazy).

Our reasoning was that apart from stopping a major incident if a component in the lifting system failed. It would also stop a very expensive sound system from hitting the floor and being destroyed. I doubt the insurance would pay out on basis of the equipment not being used within manufacturers guidlines or some other excuse that would leave the sound company short of a PA . Consequentially (excusing any possibility of a health and safety prosecution)business goes down, company struggles to pay staff etc etc.

 

Long and short being safe makes sense for all of us in the long run!

 

 

P.S

Chris's books are good but Peter Hinds is the real mind melter.