Trilight Apex

[slim_mcslim]

Slim, could you please post a URL for the page which gives this information?

 

The information can be made out, if you have a 21" monitor or good glasses, below the loading charts it says

 

Imortant :  the loading figures shown below are based upon a load being applied evenly to both lower tubes, the individual loading of a single tube can reduce overall load bearing charicteristics

 

Link To Opti Page

 

HTH

 

Paul...

 

(everytime I see HTH in a post I can't help but think Hawthorn Theatrical)

[j_b]

ummm, how bizzare - the slick/trilite kit I've used on the ground [i.e. ground support] always used it with apex up.

when it's flown I have always known it to be hung with the rear side flat . then again, we have never loaded it that heavily.

<{POST_SNAPBACK}>

Be very aware that slick and trilite are from two different manufacturers. Trilite is often used by people as ageneric term (like Hoover, only for hanging lights on :-) ) but the loading figures are very different.

 

Personally I like the slick as the data is very easy to get hold of and easy to understand, but the trilite is nice and lightweight.

 

Can you elaborate as to what on earth you mean by 'rear side flat'?

[kalmatthew]

 
|\
|/
*

Would be my guess

Where the right hand side of the page is the stage and the * is a lantern.

[j_b]

I do hope not!

[smeggie]

I mean that when there is a pair of uprights into the rig. the cross member on the front of it is like that. but with no significant loading on it.

{I.e suckys rigs}

iirc, we had

=l=====l=
 l / \ l
 l/   \l
/l     l\

that on the back of the stage. all shackled to main trusses and slung to the roof rig.

the triangle top piece was flat against the uprights to give twin attachment points.

 

{please dont jump on me - it was suckys design and rig}

 

on topic, whenever it is flown[properly] it goes apex down; easier to sling that way up.

[andy_s]

Slim, could you please post a URL for the page which gives this information?

 

The information can be made out, if you have a 21" monitor or good glasses, below the loading charts it says

 

Imortant :  the loading figures shown below are based upon a load being applied evenly to both lower tubes, the individual loading of a single tube can reduce overall load bearing charicteristics

 

Link To Opti Page

 

HTH

 

Paul...

 

(everytime I see HTH in a post I can't help but think Hawthorn Theatrical)

<{POST_SNAPBACK}>

I saw this, but thought it refered to the figures for Quad (i.e. 4 tube)

[colinmonk]

at risk of getting into a long discussion about safety and stuff...

 

colin you say that it would not twist if you had a square of trilite etc, does this not imply that it is placing parts of the truss under great strain?

 

anyone who knows more care to elaborate?

 

er? what? not sure what your statement is refering to...

 

a straight truss flown on two ( or more ) motors could twist with a moving light spinning if flown apex up, which I agree with, and you also need to take care to load the chords equally so it sits flat.

But if you flew a box apex up, using four corners blocks to make your box and hung it off say eight motors, then it wouldnt be likely to twist with moving light movement as it was a solid structure.

[Brian]

colin you say that it would not twist if you had a square of trilite etc, does this not imply that it is placing parts of the truss under great strain?

<{POST_SNAPBACK}>

 

When a moving light moves it will exert a certain force on one point of the truss which is transmitted through the truss to the suspension and thence to the supporting structure. The total amount of force exerted is the same irrespective of how the truss is flown.

 

In the straight run of truss scenario this force will be fed directly into the support cables; in the 4 bits of truss and four corners scenario the same amount of force is involved. Where this force goes will depend on where your suspension points are. It may be that the force has to be transmitted via corners into other sections before being picked up by the cables.

 

Whether this is a 'great strain' is at the heart of this thread. If you design your truss system to the manufacturers data then it isn't; if you don't design your truss then it is.

 

Would anyone be happy working in a building if they knew that the roof hadn't been designed by a structural engineer?

 

 

For a detailed story about a rigging failure see here.

[TomLyall]

Sorry I think I misunderstood what was ment about the trilite twisting. I ment due to uneven loading of the two 'bottom' chords, as apposed to the movement of the heads themselves.

 

Tom

[Chris Higgs]

You certainly could twist it (or any truss) by increasing the load at certain points.

Ladderbeam is particularly prone unless it is restrained laterally.

Trilite ladder 200 (for example) has a UDL of 222kgs on 8m (which seems high) - I am sure that is based on it being restrained to remain vertical (one chord above the other).

A point load superimposed on a uniform load that is close to the maximum design load may cause a local failure which in turn produces a loss of stiffness and hey, presto, no truss.

I believe triangular Trilite 200 has a design span of 8m when applying a maximum uniform load of 360kg.

The Trilite Quad 200 truss chart states specifically that load is to be applied equally to bottom chords, and that loading a single chord can reduce overall load carrying ability - if in doubt - ask.

Big subject. People study for years to become chartered structural engineers.

Read "Aluminium structures in the entertainment industry" by Peter Hind for a taster.

[tomchennells]

I use trilte apex up :) didnt think it made any diffrence what way -

 

but up has several advantages for me !

 

- I often need to strop it in from a girder or grid and the sigle bar ensures it is easy to hang straight (obviously using the correct brackets and carabinas)

 

- and I often need to put two lights side by side on the bottom

 

- finally I find movers are easier to rig on the two bars on the base and they seem to hang happier that way with hardly any movement from the trilite even on a 1 meter drop from the girders or grid

 

I would be intrigued to see if the movement is exactly the same both ways up ?

 

but based on my appauling physics skills I would say its ever so slightly more stable apex up ?

 

suppose it depends what its hanging from standing on etc etc

 

-tom

[Dazzler]

Has anyone read either of these books?

 

An Introduction to Rigging in the Entertainment Industry, or Rigging for Entertainment: Regulations and Practice. Both are by Chris Higgs.

 

I haven't read them yet but I have flicked through them a few times. From what I have seen of the books, the answer to the initial question may well be in one of them.

 

To those of you who have read the books.......

 

.....What did you think of them? Are they a good reference book? Are they worth the £45 they cost? (£45 for both of them, not each).

 

I am thinking of buying them but I want to know what you guys and girls think first of all.

 

Dazzler

[ianl]

Has anyone read either of these books?

 

<{POST_SNAPBACK}>

 

 

I've read both and think they are very good,

 

however you wont find the answer to specific questions like the trilight apex one in the book as the answer would be something like "it depends on the requirements and design calculations of the specific job"

instead the books discuss things you need to know to be able to (possibly) do the calculations and answer questions like that yourself

[Rob]

I think Chris's "Introduction to Rigging" is a very handy read. As mentioned, you won't get many 'easy anwers', but you do get a lot of information to eventually answer many questions yourself.

 

I've also got Peter Hind's book, "Aluminium Structures in the Entertainment Industry" (I actually ended up with it by mistake but thats another story :) ) Quite interesting stuff with regard to designing structural systems and not too heavy duty. (if you'll excuse the pun...!)

[j_b]

Yup. They're good books, as is the aluminium structures one mentioned.

 

If you can, get someone to pay for you to go on a rigging course, like for example the TF one ( I did ) if not, pay for it yourself.

 

It's one of those things, that you can be quite familiar with, but being on the course and meeting other from the industry always leads to a few new situations, that you might not have come across before.