Chain underneath counterweight cradle for weight balancing

[Gregory Allan]

Good day everyone,

I have come across a design for a manual single-purchase counterweight system with 500kg on the bar and 24m travel with the requirement for a chain suspended from the underside of the cradle. I have never come across this before in venues although I understand the theory behind it. Does anyone have any knowledge of this or know of any venues that may have this that we can visit to understand it better.

Thanks

[kitlane]

According to Toshiro Ogawa's book there was a compensation line installed at San Francisco Opera House, but this is quite an old reference.(I'm looking at the 2021 edition)

https://www.amazon.co.uk/Theatre-Engineering-Stage-Machinery-Toshiro-ebook/dp/B01J44FYD0?ref_=ast_author_dp

[Bryson]

The ESTA Technical Standards Program has a standard for that:  See section A3.9 of ANSI E1.4-1 2022.  Sadly no illustration, just a text description.

 

I've also asked a friend of mine who is rather an expert on counterweights to weigh in and if he knows of any good examples.

[Gregory Allan]

On 9/27/2024 at 6:16 PM, kitlane said:

According to Toshiro Ogawa's book there was a compensation line installed at San Francisco Opera House, but this is quite an old reference.(I'm looking at the 2021 edition)

https://www.amazon.co.uk/Theatre-Engineering-Stage-Machinery-Toshiro-ebook/dp/B01J44FYD0?ref_=ast_author_dp

Thanks 'kitlane'. After reading your comment I checked that book I have at home and the image from the San Fran Opera House. Interesting. I need to know more about it, how it stores, operates and if there are any modern improvements that could be made to take up less space. Space seems to always be a factor in relation to the lowest cradel point, return pulleys, hauling lines, etc.

[Gregory Allan]

On 9/27/2024 at 11:17 PM, Bryson said:

The ESTA Technical Standards Program has a standard for that:  See section A3.9 of ANSI E1.4-1 2022.  Sadly no illustration, just a text description.

 

I've also asked a friend of mine who is rather an expert on counterweights to weigh in and if he knows of any good examples.

Thanks 'Bryson', it would be good to know more about it. Thank you in advance for your help.

[Bryson]

His reply to my text:

 

Quote

I’d like to know more about which chain is discussed. They are called ‘compensator chains’. Generally, they are roller chains. The head flyman at Centre in the Square in Kitchener, Ontario has used proof coil chain in a slightly unconventional approach. But it works. Comp techniques are required by ANSI standard if the imbalance due to wire rope shifting exceeds 50 pounds.

 

[alistermorton]

There's some discussion of compensator chains in the Wikipedia article "Fly Systems".