Roundslings

[TomLyall]

Righto, I'm asking out of curiosity, so it'd be really appreciated if we could avoid the 'dont do it, hire a rigger' line of conversation. <_<

 

Is there a 'correct' (or more importantly, incorrect) way to use a roundsling to hang truss? Any best practices? What kind of length spanset should be used to wrap around a truss?

 

Thanks

 

Tom

[Nick Evans]

Er, how big is the truss? Normally you have a selection and you see what fits best. Truss steels have certain advantages over spansets.

[TomLyall]

Er, how big is the truss? Normally you have a selection and you see what fits best. Truss steels have certain advantages over spansets.

<{POST_SNAPBACK}>

 

Sorry, it was a completely hypathetical question, I wasn't talking about any truss specifically, just asking out of curiosity.

 

You say steels have advantages, could you elaborate? (Other than the obvious advantage in case of fire).

[Bryson]

I seem to recall the Prolyte Catalogue shows approved methods for sliging Square and Trianglular Trussing. See if you can blag one of those. I understand that Stage Electrics are now the Prolyte Distributor.

[TomLyall]

Actually, they're just one of a few companies... http://www.prolyte.nl/content/salesnetwork/country/uk.htm

 

So I shall have a look in a catalogue next time I get a chance. Thanks Bryson.

 

Sorry, just had to point that out. <_<

[andy_s]

The label attached to each roundsling (or at least the ones I've bought) shows the variations in how to use the sling and how to derate the SWL for each method. The appropriate method should be chosen for the load to be carried, as well as for the type of truss used.

[Pete McCrea]

There are several different ways of wrapping truss. The key points are:

1) Load spread evenly between the chords as far as possible

2) Minimise movement of the truss in the wrap, I.e going through the truss to prevent it being pulled out, or stop it twisting as far as possible.

3) Dressing the finished wrap so it sits properly.

4) Pick-ups should be on the node points of the truss

 

Chris Higgs first book provides a basic introduction to ways to wrap different types of truss. As mentioned above reference should also be made to the manufacturers guidance for thier truss. They will have designed it to work a specific way, and so know best.

 

If your up for learning more, then HSL and Tomcat are running a training course over three days. £350ex VAT gets you 3 days training, accomodation, go-karting evening and a certificate of attendance.

[dtgorton]

Hey Tom,

 

Just following on from the Prolyte advice above, Prolyte do have a useful tech.net section on their website which, amongst other things, gives several examples of how they'd have you wrap their trusses.

 

http://www.prolyte.nl/content/technet_basic/index.htm

 

Go Basic Tech Info, then Slinging of Trusses.

 

As I think has already been said above, you would want to apply any of these wraps to nodal points on the truss in question (both at the bottom and the top points).

 

As for truss steels having advantages over roundslings, I'm not convinced they do. Certainly I have been told on numerous occasions that they perform similarly in a fire situation in terms of load limits, as the aluminium ferrule on the SWR will give long before the SWR itself gives out, and before that happens you'd have long since evacuated the venue?? I have always worked using roundslings on trusses except where pyros are used on the near vicinity. And I've always found roundslings easier to handle...

 

Hope that's useful.

 

Dave

[Nick Evans]

Steels are generally harder wearing, which is important when the truss is landed on them. They generally have to be made to suit a particular truss and wrap, since they are not as flexible as spansets. They are generally easier to inspect than spansets, which are very good at hiding holes etc. Many venues will insist that trusses picked up with a spanset have a steel secondary between the truss and the motor, though more and more the safety will go straight to the roof, bypassing the motor as well (pointless dangerous exercise IMHO)

 

I have heard anecdotaly that when they are loaded, crimped steels and spansets fail under similar (fire) conditions, due to the expansion of the crimp under heating.

 

Spansets are much easier to wrap, since it is easier to get them under the truss if needed (not all truss needs to be picked up from the bottom chord all of the time, check with the manufacturer) and if they are too long, you can just add a wrap to shorten it. I have seen someone damage a piece of stacking truss more than once by wrapping it incorrectly, it is not just a case of chucking the spanny around it and picking it up.

[david.elsbury]

Generally we avoid landing things on slings, chaps...

And back in the real world, it happens all the time. If the truss is picked up by the bottom chord and it has no wheels what else are you supposed to do? Run around and put bits of timber underneath the truss? I am sorry but truss lands on slings all the time.

<{POST_SNAPBACK}>

 

In the 'real world' roundslings are less damaged by having trusses land on them than steels. In either case, you don't expect the slings to last very long, so manage them accordingly.

 

Sorry for the ignorance, but what are you referring to when you talk about "landing a truss on a roundsling"? The act of having it sit on the sling?

Thanks

David

[emj]

Sorry for the ignorance, but what are you referring to when you talk about "landing a truss on a round sling"? The act of having it sit on the sling?

Thanks

David

Hi David

 

It's when you ground the truss prior to disassembling (or assembling which is not grounding but can cause the same where and tear on a sling)

[TomLyall]

Sorry to interupt the discussion guys, but what do you all think to this...

 

http://www.prolyte.com/prolyft/news/news_02.htm

 

(sorry that link 'breaks' their site. bloody frames... B-)

[MartinGreen]

Sorry to interupt the discussion guys, but what do you all think to this...

 

Seen this before I think. Its a roundsling with a wire rope core. You still get a feerule secured termination so in effect you still get the same problems you get with wire rope.

 

I know a guy who tried to do them in the UK a couple of years ago and they were too expensive to get enough interest.

[Rob]

Moderation - Discussion about safeties split into new topic