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Monkey Tower


knightdan65
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Didn't expect this level of response - thanks all for your input. Given the discussion this has prompted, I feel I ought to add some more info:

 

The venue is a college studio theatre. Stage is not raked and we have 5 top bars at a height of 6.3m. Currently we use a span 500 single width tower with a platform height of 4.2m. We run a backstage production arts course here where students learn rigging and focusing at height (among other things). Here are the issues:

 

1. We get (I'm happy to say) a lot of girls on the course who tend to be on the shorter side and struggle to reach the bars without going on tippy toes and over extending - not a safe practice in my view, especially when trying to get a 25kg moving light up. A taller tower is of course an option, but only solves half the problem as you'll see in point 3...

 

2. For the purposes of instruction and paired learning exercises, I need something that can comfortably fit two operatives (either myself and a student or two students) plus some tools and equipment. This rules out tallescopes, reachlift and most small MEWPs. Equally however, anything with a footprint greater than a single width tower would cause problems when focusing with a set.

 

3. The bars themselves have a point load rating of 20kg p/m (30kg at mounting points) and so are not suitable for lifting from - we have to rope fixtures up through the tower. This becomes rather difficult when moving lights are introduced, due to size and weight.

 

So, the criteria are:

 

- a working height of around 6m

- a two person basket / platform

- a capacity to lift equipment

- a footprint no larger than a single width tower

- easily portable and storable

- under 500kgs in weight

- a sub 5k price tag

 

So far the Monkey comes closest to ticking all the boxes, the two major caveats being A) it has no rescue facility (but then, neither does a tower) and B) it requires constant repositioning (which, while certainly being a pain in the a**, isn't necessarily a safety concern in and of itself).

 

Maybe I've answered my own question, unless anyone can think of any other alternatives? In any case, I'll book a demo in.

 

Really appreciate the time everyone has taken to input on this

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(which, while certainly being a pain in the a**, isn't necessarily a safety concern in and of itself).
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I'd strongly disagree with this assessment - It looks to be such a complicated, multi step process to move the tower (compared to a talle or zargess where it's little more than "just move it") and in your venue where you'd have to cycle the tower at least 10 times for a full hang and a similar number for a focus you're gonna find people short-cutting the full official process very quickly and that is exactly how mistakes get made and accidents caused. Is there any other task in your day that takes 10+ mins and which you do 10 times a day that you don't have shortcuts for?

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(which, while certainly being a pain in the a**, isn't necessarily a safety concern in and of itself).
<br style="color: rgb(28, 40, 55); font-size: 13px; background-color: rgb(250, 251, 252);">

I'd strongly disagree with this assessment - It looks to be such a complicated, multi step process to move the tower (compared to a talle or zargess where it's little more than "just move it") and in your venue where you'd have to cycle the tower at least 10 times for a full hang and a similar number for a focus you're gonna find people short-cutting the full official process very quickly and that is exactly how mistakes get made and accidents caused. Is there any other task in your day that takes 10+ mins and which you do 10 times a day that you don't have shortcuts for?

 

 

I think a key point here is a learning process. A small grid and with students swapping about, it won't be as much of an issue as in a venue.

 

With good planning you can hit 2 bars to rig AND focus a bunch in 3 moves. Maybe some minor focus changes later but most of the work would be done before.

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Let's take a step back folks. Dan went and mentioned moving lights and rigging those without being able to haul via roof bars takes nearly all things like Zarges and Tallies out of the equation. It makes two persons and a moving head a just about impossible load for anything but a tower scaff. I know it is a small space, it is on the website, and I appreciate it is 99% empty black box but hanging moving lights and training young people sets all sorts of limits as to what is available.

 

The Monkey Tower will take the weight but the demo should include hoisting it with the lights on board. I would still probably go for a wide tower scaff at the appropriate height for students because in teaching and examining one would spend longer than normal up there. Stability is all.

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3. The bars themselves have a point load rating of 20kg p/m (30kg at mounting points) and so are not suitable for lifting from - we have to rope fixtures up through the tower. This becomes rather difficult when moving lights are introduced, due to size and weight.

 

I'm not being daft but how do you figure that your bars have insufficient weight capacity to haul moving lights up on a pulley, but sufficient weight capacity to hang those moving lights in use? That makes no sense to me. They're not heavier when being hauled up...

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Yes they are. Ignoring the dynamic load of a lift, when you rope something up the force on the pulley (or bar) is twice the force created by the weight of the item.

You have the force of gravity pulling the item down, and the force being used to lift it which must exceed the gravitational force in order to make the item move upwards.

 

Add in the dynamic stop/start load and you could easily hit 5x the weight of the item if you were being a bit enthusiastic about it.

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Yes they are. Ignoring the dynamic load of a lift, when you rope something up the force on the pulley (or bar) is twice the force created by the weight of the item.

You have the force of gravity pulling the item down, and the force being used to lift it which must exceed the gravitational force in order to make the item move upwards.

 

Add in the dynamic stop/start load and you could easily hit 5x the weight of the item if you were being a bit enthusiastic about it.

 

Ignoring the dynamic load and friction, this could be reduced by using a multiple-block arrangement (e.g. a Gun Tackle using two pulleys reduces the force on the rigging point to 100% of the load). You have to pull the rope twice the distance but the force applied is halved.

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Are you sure the bar load rating is 20kg per metre? Seems very small - if the load at a mounting point is 30kg then the max bar loading would be 60kg between two points

Even 30Kg at mounting seems low, We request 100Kg when installing static bars.

Regardless if the fixings are 3m apart and on 30Kg mounts then I can easily see how the bar rating is specified as 20Kg/m.

 

 

Yes they are. Ignoring the dynamic load of a lift, when you rope something up the force on the pulley (or bar) is twice the force created by the weight of the item.

You have the force of gravity pulling the item down, and the force being used to lift it which must exceed the gravitational force in order to make the item move upwards.

 

Add in the dynamic stop/start load and you could easily hit 5x the weight of the item if you were being a bit enthusiastic about it.

 

Ignoring the dynamic load and friction, this could be reduced by using a multiple-block arrangement (e.g. a Gun Tackle using two pulleys reduces the force on the rigging point to 100% of the load). You have to pull the rope twice the distance but the force applied is halved.

I don't see any way of reducng the load to 100% of the weight of the kit. You yourself have already mentioned 50% of force to lift. Even using 10 blocks only reduces it to 110%, friction cannot be ignored and as more block are added the friction is increased along with the additional weight of the lifting tackle. Equally the snatch force has to be considered.

 

Allowing 200% is the bare minumum figure to be considered, I allow 300% for a single pulley and more as the actual weight increases.

 

Lifting a 540Kg rack through a hole in a ceiling I requested a 2500Kg certified lifting point and additionally had the 2T chain block inspected for the occasion.

 

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You need a decent tower not this over complicated solution that gives you a mere 30 cm more height. If you do get one chain those outrigger pins to the chassis.

 

The biggest issue for me is the fact that the designers have festooned the outrigger housings with hazard tape but the main hazard - that towbar which extends right outside the footprint and will be walked into frequently and painfully in poor lighting - has none. I wouldn't give it houseroom for that reason alone.

Edited by Junior8
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The venue is a college studio theatre. Stage is not raked and we have 5 top bars at a height of 6.3m. Currently we use a span 500 single width tower with a platform height of 4.2m. We run a backstage production arts course here where students learn rigging and focusing at height (among other things). Here are the issues:

 

I am not being funny but like... simple solution alert (I'm from the school of thought that simple solution is often best solution). The Span 500 Manual says that for a single width tower, you can go up to a maximum platform height of 8m (that's a working height of around 9m). So, 6m is well within the specification of the tower you already have. All you need to do is buy an extra set of uprights (probably just half height ones, assuming your handrails are already at circa 5m), some extra diagonals, maybe an extra platform too - depending what you've got so far. Cost wise this is bound to be the most efficient approach. Even if you are attracted to your monkey tower... why not give the extra scaff tower a shot, see how it works out for you? You'll always find having a scaff tower useful, whatever else you might buy in addition later on.

 

As a thought - I don't know if you'd considered this - but remember the monkey tower will need a thorough examination as per LOLER. 6/12 monthly might be slightly open to interpretation but I would probably err on the side of 6-monthly since, whilst it is not lifting people (which is a mandated 6 monthly), it is supporting people on its mechanisms. You may be able to lump that in with your other annual lifting inspections (if you have any?) to save money but if not, remember to budget probably not much short of a grand a year having 2 visits from a lifting equipment inspector. On the access tower, by contrast, I would dare say you can inspect that yourself. A visual examination of all parts to be free of damage, deformities etc would fulfil your obligations under the WAHR/PUWER, providing that records are kept to that effect.

 

As a final thought, you say this:

 

it requires constant repositioning (which, while certainly being a pain in the a**, isn't necessarily a safety concern in and of itself).

 

My experience, and I'm sure that of countless health and safety professionals... would only be that equipment which is a pain in the a** to use is the last equipment to be chosen for a job. I've witnessed 3 hospital-stay falls during my career. Despite 10 years of climbing on structures and rope access, neither were of that variety. 2 were a small fault (a lantern slipping off focus, and a lamp blowing) right before doors where somebody said "quick, grab the ladder and go fix that", the other was changing a lightbulb in the office by standing on a swivel chair which, once off-balance, spun wildly and buckaroo'd the technician. Time is always an issue in theatre. Fatigue is usually an issue in theatre. Equipment which people relate to as having poor time and fatigue efficiency, will be the first to get substituted for a ladder, or for climbing on something which isn't a ladder.

 

I'm not being grumpy and saying "don't do it" ... but honestly that video of windy-up-windy-down fills me with dread. I've done enough time on a Genie superlift that half way through tech week if it came to dragging that trailer out of the wings to do a sweaty great arms workout on the winch to then climb up to the basket to do a thing, only to have to come down and do 2 more arms workouts to reposition it 10 feet along the bar... I'd probably be the first one guilty of running up the Zarges. I guess maybe in an educational setting you might be able to police that a little better than a commercial theatrical environment. But equally if your goal as per point (1) is inclusion of all body types, having to do 2 gym sessions for every 6 feet of lighting bar might be problematic for some people (of all genders!).

Edited by dje
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Your students are there to learn. It will be much better to teach them how to use widely used equipment, such as a scaff tower, competently and safely as part of their education. Your students are much more likely to be asked to use a scaff tower in later real life, particularly if not working within a standard theatre environment. Erecting and dismantling a scaff tower is also a good practical lesson in teamwork that cannot be taught in a classroom or over a video link.
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Your students are there to learn. It will be much better to teach them how to use widely used equipment, such as a scaff tower, competently and safely as part of their education. Your students are much more likely to be asked to use a scaff tower in later real life, particularly if not working within a standard theatre environment. Erecting and dismantling a scaff tower is also a good practical lesson in teamwork that cannot be taught in a classroom or over a video link.

 

This is also a great point I think.

I wonder - as a total aside - what the process would be to get the OP registered as a PASMA trainer / assessor. Wouldn't it be great if students could be taught the correct 'PASMA' process for erecting the tower, and leave college with an industry ticket too?

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