Winches, Working Load Limits and ...................................

[BLC392]

Winches, Working Load Limits and ………………………

I would like to put this forward to the collective of knowledge.

I purchased two winches, one electric and the other hydraulic. Both rated at 20,000lb.

Before I go any further, I did email the company three times requesting assistance, and spoke with support, twice. No return email response received.

There is an atmosphere of excitement when freight arrives and it’s not Christmas. So, when you open up the packaging, of the same load rated winches, one does expect that some things should be equal? Right?

The first being the supplied winch hook assembly for the synthetic. The winch specification is Layer 1 provides 20000lb (9072kg) of pulling force. The supplied hook assembly with hammerlock has a Working Load Limit (WLL) of 3.2t. This is substantially less than that of the capability of the winch. I understand that the Minimum Breaking Limit (MBL) of the hook assembly is the WLL times a safety factor multiplier (What is the safety factor multiplier in this case?).

Definition: WLL

Working Load Limit (WLL) is the ‘maximum working load’ designed by the manufacturer. This load represents a mass or force that is much less than that required to make the lifting equipment fail or yield, also known as the Minimum Breaking Load (MBL). WLL is calculated by dividing the MBL by a safety factor.

What further raises this point of the suitability of the 3.2t WLL of the synthetic hook assembly is that I also purchased the Hydraulic 20000lb winch? The hook assembly of the hydraulic winch being 8.2t WLL. The WLL of the hydraulic winch hook assembly is less than that of the winch specification for Layer 1, but somewhat closer to the rating. The disparity of the two is quite distinctive. Irrespective of the winch motive supply, hydraulic or electric, the load capability is the same, 20000lb (9.072t), the WLL of both hook assemblies should also at least be equivalent to or greater than the winch capacity (not including a safety factor multiplier).


Which one of these is not like the other?

I initially believed that, this is not really a concern, given that I would remove the hooks and replace with rated bow shackles and remove a point of failure from the system. But alas, the thimble eyelet dimension.

I considered replacing the 3.2t WLL hook assembly with an appropriate rated bow shackle. Research of rated bow shackles with at least a WLL of 9072kg lead to another discovery, the size of the thimble/eye of the synthetic rope. The working diameter of the thimble is approximately 23mm, measured with Vernier Calipers. The most appropriate WLL size bow shackle for this application is at least 9.5t, being at least equivalent to or greater than the winch capacity. The specification for 9.5t WLL bow shackle has a screw pin with a diameter of 32mm. The diameter of the screw pin exceeds the working diameter of the thimble/eye of the synthetic rope.

The working diameter of the hydraulic winch cable thimble is suitable for rated bow shackles up to 13.5t, therefore being equivalent to or greater than the winch capacity.

A bow shackle with a screw pin that will work within the thimble of the synthetic rope is a bow shackle with a 4.7t WLL, approximately half the capacity of the winch.

Where to from here? Did I misinterpret something? Thoughts? Options?

 

[dietert]

Hi mate
Just went and had a look at the winch hook on my Warn 15000. I have wire rope/cable. The hook itself does not have WLL rating other than 'Forged' and 'High Test' and '1/2'. The pin securing the hook through the wire rope loop measures 13mm. Now that flies in the face of your 32mm shackle pin size. And I note there's no thimble in my loop.

The rated shackles I have are, I think, an ARB product rated at 8.5T. The shackle pin measures ~28.5mm. The winch has been used to pull out one Landcrusier from a bog and to pull down/out a couple of mediums sized trees from the garden. So no real test of the winch capability itself, but my point is no problem with the hook or pin to date.

But to look at it as it is, clearly there's an anomaly. Given I haven't previously heard of winch hooks or the pin itself failing, am I/we now reading too much into this (not meaning to take it lightly given the potential for a disaster whenever winching).

I mean Warn is a rated company/winch builder who would have done their homework.

 

[billiebob]

I think we live in a world where the retail sale of a winch to a 4 wheeler is often jewelry for the front bumper. 1 in 100 never really need/use the winch. 1 in 1000 guys will ever stress the components. Those few guys almost always operate in a community which modifies everything.

I would say the electric winch is for retail consumers, quick and easy install. The hydraulic winch is geared for industrial applications since the install involves a hydraulic power supply, plumbing and it has a 100% duty cycle.

Retail means margins and quick sale and competitive pricing. Commercial means actual function and regular use.

I'm curious, was there a price difference? Hydraulic vs electric. Installed and ready to pull.

And what brand?

 

[billiebob]

Why did you buy 2 20K pound winches? Where are you installing them?

 

[Howard70]

I agree with Verkstad - high alloy shackles are great when you desire the highest capacity for the lightest weight or, in your case the smallest pin. This Skookum shackle might fit your needs. Be prepared - they are not inexpensive.

Howard L. Snell

 

[Fugly]

20000lb = 9.09tonne

Industry Standard here in Oz
SWL = Safe Working Load this was superceeded
WLL = Working Load Limit which became
MRC = Maximum Rated Capacity

If was fitting those 2 winches to my truck I would piss both hooks off
And get 2x BV-1310 which are 100 Grade Hooks Rated/ MRC 11.6 Tonne

Just my 2 bobs worth

 

[DaveInDenver]

Also consider rigging is usually rated for overhead use and vehicle winches aren't, so the two sets of requirements for stated WLL aren't the same.

It's conceivable that a U.S. engineer could rerate an ANSI Β30 device to SAE J706 standards. B30 requires typically 5 times WLL design safety factor and a 2 times WLL proof test. SAE J706 requires the winch to be capable of withstanding 2 times the WLL of the rope on its drum.

Using a device from one standard on one from another means you'd have to recalculate WLL. A 20,000 lbs recovery winch rated per SAE J706 would have presumably been designed to be capable of 40,000 lbs or 20 tons. A hook or shackle with an B30 WLL of 4 tons would have been originally designed to withstand 20 tons (and been tested to 8 tons). It would then be perhaps suitable for a J706 WLL of 10 tons.

You could look at it the other way, if you wanted to rate your 20,000 lbs winch for overhead use it would probably be a 2 ton winch, not 10 tons.

I'm certainly not suggesting a 3.2 ton slip hook is appropriate for a 20,000 lbs winch, but I am pointing out that WLL is contextual, not a universal or hard-fast number. Building margin in is of course better.

 

[charlieaarons]

Owning a 26000 lb vehicle with a 20k dp winch in the front and a 15k Superwinch in the rear (both used in the field) I agree with most of the above. Remember a winch only produces rated pull when on the last layer of cable. With a full drum figure about half.
The hydraulic winch hook is adequate IF built by a quality mfg (like Crosby, if no mfg stamp on hook replace it). I’d simply use the same hook on the electric.
What is the application? And again, what brand winches?
If I had insisted on the 1.5xweight rule I would have 40000 lb winches on the truck, ridiculous even for a Unimog , they weigh too much and are usually enormous. And yet I pulled a 35000 lb Mercedes tractor-trailer out of the mud up a slight incline in Mongolia.

 

[BLC392]

'If was fitting those 2 winches to my truck I would **** both hooks off' - Looking at fitting hammerlocks (HL). The throat of the HL will allow for a >9.5t rated shackle.

Application is for an Isuzu FTS700, hydraulic front, electric rear.

Winches are by RUNVA. I don’t wish to get into the Chinese debate. I have also purchased reputable brand tyres, and these are manufactured in China too.

My thought process for two winches was balancing up the cost vs. paying someone for remote recovery. In reality, I hope that I never need either winch, but it is better to have it and not need it than to need it and not have it.

The disparity of the two hooks for the same capacity winch, I think this is concerning, given that one of the hooks is 1/3 the capacity. Yes, I have emailed the company (3 times) and no response received.

B