CM chain hoist fails its yearly certification

[djandydee]

I have recently left 4 of my motors over to another production company who are certified to certify!. A few days later I get a call to say that 3 have failed due to a small nick in their chain. The chains are 22M long and the nicks are about half way along.

 

To re-chain them will cost £1200 plus labour - holy crap!

 

I know safety is absolutely paramount and so this conversation should stop immediatly..................but how does a small nick in a chain leave it totally un-usable. Surely all it takes is the hook to be dropped from a few inches onto the chain in the box to cause a nick. Are those chains not massivly over engineered? Those units have only done about 6 small gigs.

 

Rather than pay I have opted for the cheeper approach - My motors now have 12M chains and I will hire in when I need longer.

[AndyJones]

There is nothing in the official Lodestar Manual that says about nicks in the chain, The only bit that may be relevant is about general chain wear, which is:

 

If the stock diameter is 0.010 inches(0.254mm), or more, less than the stock diameter of the unworn link, the chain must be replaced

 

So I guess you could measure where the link in and see if it is more than described in the manual? But it seems like you have already scrapped it.

 

(Note the manual that I quote from is Manual No. E627-B page 10 para 3)

[Pete McCrea]

Is it worth a second opinion from an alternative testing house?

[Biro]

I was going to say, go see someone else about that, I had a nick (less than a mil) on one chain and took it in to be checked out, it passed.

[Jivemaster]

If the "nicks" were half way into the chain length then you should still be the owner of some chain in straight lengths for use as stingers, once fitted with shackles.

[csg]

not sure that is a good idea,im sure that is discouraged, along with stac chains

 

it would also be difficult getting decent sized shackle pins through 1 ton lodestar chain.

[kitlane]

not sure that is a good idea,im sure that is discouraged, along with stac chains

 

it would also be difficult getting decent sized shackle pins through 1 ton lodestar chain.

 

Are you saying that using chain as a stinger is discouraged? Why would that be?

[adamwb]

Hi Andrew,

 

I know we have spoken on the phone about this already but thought I would put up a quick post to try and clarify things as the UK CM Entertainment distributor.

 

The following paragraph comes from the CM Lodestar manual:

 

Chain Inspection: Make a link by link inspection for nicks, gouges, twisted links, weld splatter, corrosion pits, striations (minute parallel lines), cracks in weld areas, wear and stretching. Chain with any one of these defects must be replaced

 

This is the guideline we work to when inspecting Lodestars, and this same is taught in the CM Motor schools.

 

CM chain is case hardened. This basically means the outside of the links are treated and hardened, but the material inside the link is relatively soft. The Hard part of the chain is designed to hold the load and be hard wearing, and the soft part to allow elongation. The chain is engineered in this way to meet relevant standards.

 

The Hardened area is less than 1mm of the outside of the link but it would take more than dropping the motor hook or similar to nick the chain.

 

CM chain has a design factor of 8:1 and as such reduces risk of failure. However, any damage to the chain will reduce the factor of safety and therefore the chain will need to be replaced.

 

If a link has a nick or a gouge deep enough to go through the case hardening then it can substantially weaken the link. As the saying goes, a chain is only as strong as its weakest link.

 

I suspect the engineer working on your hoists was working to the above guidelines, to hence the failure of the chain. At the end of the day the engineer is signing your certificate so the responsibility lies with him.

 

As discussed over the phone, we are happy to work with you and the inspection company to resolve this or any other future issues you may have.

 

I hope this clears things up.

 

Adam.

 

P.S. One other thing. STAC chain (or similar) is a "Long Link" Chain which does not meet CE Machinery directive for lifting purposes. Chain used in hoists is "Short link" and is approved for lifting, hence its use in hoists, chain slings etc.

[Seano]

P.S. One other thing. STAC chain (or similar) is a "Long Link" Chain which does not meet CE Machinery directive for lifting purposes.

 

Not wishing to derail the thread with this old chestnut, but not entirely true.

 

The Machinery Directive doesn't say you can't use a long link chain for 'lifting purposes' it says you can't use a long-link chain as a 'lifting accessory'.

The distinction is significant because it has its own definition of what a 'lifting accessory' is, which is not the same as LOLER.

 

According to the Machinery Directive, a lifting accessory is used between a lifting machine and the load. (ie: in our industry - *below* the hoist).

 

The Machinery Directive seems to have nothing to say about rigging used above the hoist, where in many cases STAC is by far the best product on the market for building and adjusting bridles.

[Simon Lewis]

Not wishing to derail the thread with this old chestnut, but not entirely true...

 

and if I remember what was said at a recent Crosby seminar correctly, STAC will be "cleared" for such use in the near future.

[adamwb]

Yes Seano, There is room for interpretaion, Is it lifting? is it suspending? etc, and your understanding is very acurate. I was mearly trying to explain the difference between the chain used in a hoist and what people refer to as STAC. (STAC is a brand name of CM for thier own long link chain)

 

You are right Simon, Crosby have been working hard to change things as they also manufacturer a 13mm long link chain. Lets see what the future holds.

[RogerB]

Hi all

 

The HSE has recently ruled that STAC (specifically the CM brand, not any copies) is now approved for theatrical rigging purposes, although on the disappointingly dubious grounds that it forms part of the load. The HSE has stated that no enforcemnt action will be taken against such use, providing it is being used correctly (mainly so that there is no possibility of bending one of the long links sideways). As part of the rersearch, we sent some real STAC and some copies to the H&S Labs in Buxton - the copies all failed at scarily low levels, the real stuff was fine. Further details from the PSA.

 

Kind regards

 

Roger B

[Joe Betts]

Hi all

 

The HSE has recently ruled that STAC (specifically the CM brand, not any copies) is now approved for theatrical rigging purposes, although on the disappointingly dubious grounds that it forms part of the load. The HSE has stated that no enforcemnt action will be taken against such use, providing it is being used correctly (mainly so that there is no possibility of bending one of the long links sideways). As part of the rersearch, we sent some real STAC and some copies to the H&S Labs in Buxton - the copies all failed at scarily low levels, the real stuff was fine. Further details from the PSA.

 

Kind regards

 

Roger B

 

Cant find any info re this on PSA site, or on google.

 

I cant see how a piece of "Top Rigging" used to shorten and position bridle legs could possibly form "Part of the Load"

If this is really what they have said, it is no more allowed for use than it ever was, as that only allows you to hang bits of STAC

from your truss / hoist with nothing on the other end.

 

Can someone clarify what has or has not happened here?

 

A link to some official statement would be good.

[simonwest]

just a quick thing from another forum which you may or may not have seen....but here it is anyway as it may be important to you....or not

To All,

 

We had a Prostar hoist fail on a recent job.

The brake driver pin which connects the drive train to the brake disk sheared off causing the chain with the load on it to drop freely.

We were fortunate no one was hurt and there was no equipment damage.

 

We alerted CM, who advised us that there was batch of Prostars sold with defective brake driver pins.

CM sent a safety notice to all the distributors who received hoists from this batch.

We never received a notice from our distributor.

This leads us to believe there may be other end users who did not receive this notice.

 

The batch in question has serial numbers which end with the letters RP through SD indicating the hoists were manufactured between Feb 2005 and April 2006

The attached document relates serial numbers to the manufacturing date of the hoists.

 

To fix this problem we have opted to retrofit all of our Prostars that had a driver pin, regardless of what batch it was from, with the new C208 splined shaft kit that eliminates the driver pin entirely.

 

Please check your stock and take appropriate action to quarantine and repair any hoists which have this problem.

 

Feel free to forward this note to anyone else who has Prostar hoists.

 

cheers