Counterweight Bars

[Tim gregory]

Last week we added a couple of additional hand line sets to our grid for panto season. This was the first time we have added any permanent rigging since refurbishing the old counterweight line sets and adding motorised LX bars some 12 years ago.

 

At that time we added an additional low fly gallery and moved all the rope locks up to this level so the controls weren't at stage level.

The problem with hand lines now is that the height is restricted making it difficult when they want to pull out full height drops.

 

While we were adding the new lines I figured that it wouldn't be a huge amount more work (and far more usable) to add additional counterweight lines but for the fact of having to add full height guide rails for the cradles. Then it struck me that if we could use tensioned wire ropes as the guides it would make this a far simpler job.

 

I hunted the web and couldn't find any examples of this other than these cradles on Flints site that seem to suggest they use wire rope as a guide.

 

Has anyone seen a counterweight system with wire rope guides before and are there any obvious disadvantages to doing this?

 

Thanks,

 

Tim

[mac.calder]

The main disadvantage I can see is that to keep the guide wires for providing too much lateral play you need to tension the wires... a lot. Multiply by the number of lines... you are talking some serious additional force on your grid. It will probably still have more lateral movement than steel which means that you could not go high-density (where cradles often pass with millimeters between them - or you run the risk of have cradles banging in to each other which could be really bad.

[kitlane]

The main disadvantage I can see is that to keep the guide wires for providing too much lateral play you need to tension the wires... a lot. Multiply by the number of lines... you are talking some serious additional force on your grid. It will probably still have more lateral movement than steel which means that you could not go high-density (where cradles often pass with millimeters between them - or you run the risk of have cradles banging in to each other which could be really bad.

 

I have experience of doing this and I can confirm that you need a serious amount of tension to get something that will still flap about. What is the height of the grid? The longer the lines the more tension you will need. In 'The Stage Rigging Handbook' Jay O. Glerum states "These generally should not be used for line sets with more than 35 feet of travel. No matter how tight the guide wires are, it is impossible to keep the arbor from swinging side to side. If they are used for systems with greater travel distances, the line sets should be spaced far enough apart so the arbors do not hit each other."

[Tim gregory]

Thanks, that is very helpful.

 

The height of the grid is about 50ft so it would be significant tension and play!

 

The additional lines are to add a few extra bars in the large gaps between existing counterweights (we currently have a set of 3 counterweights upstage and a set of 3 midstage).

These wouldn't be positioned near each other so carriages clashing shouldn't be a problem.

 

What are the best options for a solid guide rail?

 

Tim

[paulears]

We've got the odd wire rope guided counterweight cradle - installed as temporary in 1984!

 

They're ok, but a pain to use because they tend to twist the cradle at about half height. Ours are used with slightly too much weight in them to provide tension to a header that sags in the middle. I would hate to use them for regular use. They are great for those one-off requirements, but just not the thing for permanency - which is what ours have become.

[kitlane]

Thanks, that is very helpful.

 

The height of the grid is about 50ft so it would be significant tension and play!

 

The additional lines are to add a few extra bars in the large gaps between existing counterweights (we currently have a set of 3 counterweights upstage and a set of 3 midstage).

These wouldn't be positioned near each other so carriages clashing shouldn't be a problem.

 

What are the best options for a solid guide rail?

 

Tim

 

Our grid is about 50ft as well. If there is plenty of space then it may work. If the bars are static during the show (e.g. LX or borders) then it will probably be fine. If you want to be able to move them during a show (e.g. backcloth) then it may be less successful.

 

I've never built a guide rail but my experience of maintaining them and replacing wheels/tyres etc. leads me to suggest it would be a job best left to an experienced company. If the track isnt straight and smooth over its full length or if the wheels are too loose or too tight on the track you will have a very noisy system.

[Tim gregory]

We've got the odd wire rope guided counterweight cradle - installed as temporary in 1984!

 

They're ok, but a pain to use because they tend to twist the cradle at about half height. Ours are used with slightly too much weight in them to provide tension to a header that sags in the middle. I would hate to use them for regular use. They are great for those one-off requirements, but just not the thing for permanency - which is what ours have become.

 

Yep I know what that's like. Not quite as 'temporary' as yours but the lines we added where replacing a temporary arrangement fitted at least 10 years ago.

 

Thanks that is very useful to know.

 

Our grid is about 50ft as well. If there is plenty of space then it may work. If the bars are static during the show (e.g. LX or borders) then it will probably be fine. If you want to be able to move them during a show (e.g. backcloth) then it may be less successful.

 

I've never built a guide rail but my experience of maintaining them and replacing wheels/tyres etc. leads me to suggest it would be a job best left to an experienced company. If the track isnt straight and smooth over its full length or if the wheels are too loose or too tight on the track you will have a very noisy system.

 

We must have been quite lucky with our rails and carriages then. We refurbished the counterweight lines some 12 years ago, replacing every single bolt and fixing, bars, hemp, wire rope, and bearings. Other than the LOLER inspections and replacing some hemp it hasn't needed any work. Admittedly it doesn't get used excessivly and needs a little bit of tlc now.

 

Ive got to say that comming from motors and truss to doing a project like that was quite an enjoyable learning curve.

 

Tim