Steel cable on lifters going flat

[andrew gissing]

Hi guys,

I've taken on a new role with a major PA company in my city (Neale, you can guess who and you'll be right).

We've got 4 winch up lifting towers and the steel cable appears to have flattened out in a few sections. I'm guessing this is because it's where it comes off the reel and spends most of it's time in that position.

I'd like to ask some advice - should I be concerned that it's no longer flat or is this ok ?

When speakers are hung the weight is on the pins so the cable is just for in-between the pins going up and down.

I realise that the internet is no substitute for professional advice especially where safety is concerned but, I just wanted to get an opinion before I start tracking down someone in my city who can advise on this.

two pics attached; sorry the second one is a bit blurry.

The cable isn't frayed; just flattened.

Regards,

Andrew

 

[Rob Timmerman]

Re: Steel cable on lifters going flat

Hi guys,

I've taken on a new role with a major PA company in my city (Neale, you can guess who and you'll be right).

We've got 4 winch up lifting towers and the steel cable appears to have flattened out in a few sections. I'm guessing this is because it's where it comes off the reel and spends most of it's time in that position.

I'd like to ask some advice - should I be concerned that it's no longer flat or is this ok ?

When speakers are hung the weight is on the pins so the cable is just for in-between the pins going up and down.

I realise that the internet is no substitute for professional advice especially where safety is concerned but, I just wanted to get an opinion before I start tracking down someone in my city who can advise on this.

two pics attached; sorry the second one is a bit blurry.

The cable isn't frayed; just flattened.

Regards,

Andrew

ANY deformities in wire rope will cause a reduction in the breaking strength of the rope, and are cause for concern if the wire rope is used in any load-bearing application (e.g. lifting or hoisting). And in that first photo, it looks like there's more than just crushing going on - it looks like there may be several broken strands in the rope as well.

Here are a couple of references in the inspection of wire ropes that a quick web search turned up.
http://www.unionrope.com/Resource_/...nspect-and-when-to-replace-your-wire-rope.pdf
http://www.wescovan.com/catalogs/wireropeinspection.pdf

 

[Jordan Lahr]

Re: Steel cable on lifters going flat

When in doubt a call to the manufacture is in order.

 

[Tim McCulloch]

Re: Steel cable on lifters going flat

Hi guys,

I've taken on a new role with a major PA company in my city (Neale, you can guess who and you'll be right).

We've got 4 winch up lifting towers and the steel cable appears to have flattened out in a few sections. I'm guessing this is because it's where it comes off the reel and spends most of it's time in that position.

I'd like to ask some advice - should I be concerned that it's no longer flat or is this ok ?

When speakers are hung the weight is on the pins so the cable is just for in-between the pins going up and down.

I realise that the internet is no substitute for professional advice especially where safety is concerned but, I just wanted to get an opinion before I start tracking down someone in my city who can advise on this.

two pics attached; sorry the second one is a bit blurry.

The cable isn't frayed; just flattened.

Regards,

Andrew

I agree with Rob Timmerman's assessment: it's crushed and you have broken strands. It's on the way to failure. Probably not today, maybe not tomorrow, but the failure process has begun.

With the extensible lift, you probably have other issues related to overloading lurking within the mast sections: pulleys with flat spots, damaged guides, etc. I suggest having it looked over by a technician experienced and trained to evaluate and rebuild these lifts.

We have 8 Genie-type lifts and rebuild 2 a year, it seems. The weight ratings are not forgiving, there is no 'headroom' built in. If it's rated for 250kg, it's NOT rated for 251. Some coworkers and crews have a hard time understanding that.

 

[andrew gissing]

Re: Steel cable on lifters going flat

Thanks all.

We're trying to get info from the manufacturer; still waiting on them.

We have found out though that whilst the stand is rated to 300Kg, the rope is rated to 3000Kg.

Again thanks guys; we will replace and Tim thanks for the advice about getting other parts checked out.

Regards,

Andrew

 

[andrew gissing]

Re: Steel cable on lifters going flat

Special thanks for the links Rob; great resource there.

andrew

 

[Tim McCulloch]

Re: Steel cable on lifters going flat

Thanks all.

We're trying to get info from the manufacturer; still waiting on them.

We have found out though that whilst the stand is rated to 300Kg, the rope is rated to 3000Kg.

Again thanks guys; we will replace and Tim thanks for the advice about getting other parts checked out.

Regards,

Andrew

Not sure of the exact wire rope (size, construction), but I'd guess that the 3000Kg rating is near the breaking strength. Rope works because the individual strands that make up the lay are free (mostly) to slip and slide, allowing the rope to conform. Things that restrict that movement, like crushed sections, prevent the load on each strand from being borne equally. The overloading of strands causes them to break. It is not necessary to exceed the ultimate breaking strength to have a failure, only a compromised product.