Winch wire thickness.

[Aaron]

I was just wondering why my hand winch cable (4.8t) is 17mm thick, and when I look at tow truck winch cable, its only looks 10. Surely there winches that look massive are of a much bigger capacity than my hand winch.

[Slunnie]

I dunno. Perhaps to get traction on the cable.

Hand winches scare the hell out of me. Not only because it means a bit more than holding a button in, but when the wires loaded and singing I just can't help but wonder what would happen if the cable let go. Somehow I doubt you'd feel a thing... so perhaps this also contributes to why the wire is thick.

[Aaron]

So is your official response "over engineering"

I have the reflexes of the Karate Kid... Ill out run a snapping winch cable any day of the week :)

[Slunnie]

My official response is "I dunno" You must be "the one... neo!" from the Matrix!:lol2:

But I would hope over engineering is the case.

[Aaron]

Well it does make sense.

[1103.9TDI]

[Aaron So is your official response "over engineering"

I have the reflexes of the Karate Kid... Ill out run a snapping winch cable any day of the week
2nd May 2008 10:21 PM


Be that as it may; the result could include a rather bruised 'Vanilla leaf air freshener', amongst other casualties!.......:)

[ladas]

Just a straight forward observation

Doesn't matter how thick the cable is - it depends on the collective strength of the individual strands

..........and of course the material it is made from - ie the quality of each strand,

plus of course the way those strands are wound

If you take - lets say 50 strands - in a straight line - not wound - and then you take the same 50 strands wound in a certain fashion = the strength would be X, but if wound (ie tripple weave/platted) the strength would be X x 5 or 6, whereas a straight spiral wound cable would only have a strength of X x 2.5 or 3

at the end of the day winch cables are (or should be) rated - and there rating is based on science and testing

Remember the english saying "never mind the quality - feel the width"

[EchiDna]

i would have thought the average tow truck pulling a vehicle along tarmac would have FAR less rolling resistance than your average 4x4 sunk in mud up to the axles...

[Bush65]

Just a straight forward observation

Doesn't matter how thick the cable is - it depends on the collective strength of the individual strands

..........and of course the material it is made from - ie the quality of each strand,

plus of course the way those strands are wound

If you take - lets say 50 strands - in a straight line - not wound - and then you take the same 50 strands wound in a certain fashion = the strength would be X, but if wound (ie tripple weave/platted) the strength would be X x 5 or 6, whereas a straight spiral wound cable would only have a strength of X x 2.5 or 3

at the end of the day winch cables are (or should be) rated - and there rating is based on science and testing

Remember the english saying "never mind the quality - feel the width"
To me this sounds like conjecture from someone who is pulling numbers from out of the air, and doesn't know much about steel wire ropes :eek:

When you start with an example using 50 strands, I suspect that you don't know what a strand (in the context of wire rope construction) is.

Most wire ropes have 6 or 7 strands. Non rotating ropes (used on multi rope mine winders) and elevator ropes have more - I don't have a handbook with me, but I guess around 12. Flat balance ropes (used on mine winders) could have more strands (depending on heavy the rope has to be), I have never seen one (except in wire rope or winder handbooks) but 50 strands sound ridiculous to me.

...the strength would be X, but if wound (ie tripple weave/platted) the strength would be X x 5 or 6, whereas a straight spiral wound cable would only have a strength of X x 2.5 or 3
...
Where do these numbers come from?

[Bush65]

I was just wondering why my hand winch cable (4.8t) is 17mm thick, and when I look at tow truck winch cable, its only looks 10. Surely there winches that look massive are of a much bigger capacity than my hand winch.
A winch can utilise the strength of the rope because of the manner in which the rope is anchored to the winch drum.

I haven't looked inside a tirfor for so long and my memory of the mechanism is vague. I'm thinking they transfer the load on the rope, only through the outer wires of the rope to the grippers.

17mm wire rope is much larger than tirfors I have used.

[abaddonxi]

I suspect, but am not sure, that hand winch rope needs to be thicker because the winch grips the rope in jaws rather than winding it on a drum.

Cheers
Simon

[Bushie]

I think one of the other factors is that handwinches such as tirfor are rated at a lift capacity (Tu16 = 1.6 tonne) and so have a safety factor built in, I think minimum 5X lifting capacity (could be more) so the cable would not break before ~9 tonne.

Most recreational winches are rated at (or near) the breaking strain of the cable ie Warn 8500lb winch cable 8mm breaking strain around <4 tonne.

Personally I would be more worried about the electric winch cable breaking before the hand winch.


Martyn

[ladas]

To me this sounds like conjecture from someone who is pulling numbers from out of the air, and doesn't know much about steel wire ropes :eek:

When you start with an example using 50 strands, I suspect that you don't know what a strand (in the context of wire rope construction) is.

Most wire ropes have 6 or 7 strands. Non rotating ropes (used on multi rope mine winders) and elevator ropes have more - I don't have a handbook with me, but I guess around 12. Flat balance ropes (used on mine winders) could have more strands (depending on heavy the rope has to be), I have never seen one (except in wire rope or winder handbooks) but 50 strands sound ridiculous to me.

Where do these numbers come from?

Actually it was a typo and should have read 5 strands

[Tank]

I dunno. Perhaps to get traction on the cable.

Hand winches scare the hell out of me. Not only because it means a bit more than holding a button in, but when the wires loaded and singing I just can't help but wonder what would happen if the cable let go. Somehow I doubt you'd feel a thing... so perhaps this also contributes to why the wire is thick.
Hand winches (Tirfors) have shear pins in the operating lever, designed to break (shear) well before the Guaranteed Breaking Strain of the wire rope, Aaron's winch cable which he states has a Safe Working Load (SWL) (or Working Load Limit WLL) of 4.8 Tonne has a built in Safety Factor (SF) (GBS divided by SF = SWL or WLL). The SF varies with the use, but in this case the SF would be 5, which means the GBS would be the SWL X SF = GBS which is 4.8T X 5 = 24T.
The size of the cable on a winch determines the SWL of a winch, NOT what the Manufacturer or Retailer says, for example how many winches do you see that are advertised as a 12,000lb(5,500kg.) winch with 10mm cable which has a SWL of around 1100kg, these winches are being sold with the GBS of the cable advertised as the normal usage loads and not the SWL or WLL, no wonder there are so many accidents, I worked in heavy industry for years as a Rigger, crane driver, Dogman and never seen a cable break, yet it is a common occurrence in the 4WD community, Regards Frank.

[Tank]

To me this sounds like conjecture from someone who is pulling numbers from out of the air, and doesn't know much about steel wire ropes :eek:

When you start with an example using 50 strands, I suspect that you don't know what a strand (in the context of wire rope construction) is.

Most wire ropes have 6 or 7 strands. Non rotating ropes (used on multi rope mine winders) and elevator ropes have more - I don't have a handbook with me, but I guess around 12. Flat balance ropes (used on mine winders) could have more strands (depending on heavy the rope has to be), I have never seen one (except in wire rope or winder handbooks) but 50 strands sound ridiculous to me.

Where do these numbers come from?
General Purpose (GP) wire rope used for slings, snotters and other GP use is usually Galvanised high tensile wire with 19 Wires twisted into a Strand, which is then twisted into 6 strands around a lubricated rope core to form a GP cable, Winch cable, both Hand and Powered (Winches) has an extra Strand in the core replacing the rope core, this is to prevent crushing when the cable is run over sheaves or through a Tirfor hand cable, it also adds about 10% to the strength of the cable.
There are Hundreds of combinations of wire rope cable, I have used 32 Strand wire to make a sling for lifting massive turbine wheels (50+ tonnes), because standard GP 6 (3"dia.) strand rope was too stiff and inflexible, I have seen non rotating crane wire cable with 64 strands, Regards Frank.

[Blknight.aus]

the reason the SWR for tirfors is so thick for its rated load is simple.

they use a pair of jaws to grip the rope so the rope needs to be thicker to offer the purchase requirement.

its nearly impossable to break a rope outside of a tirfor by overtensioning if you put the wrong strenght safetypin in what will happen is the strands under the jaws will shear away and make an ugly mess inside the tirfor.

[Aaron]

Bush - So are you saying that with hand winches they need a bigger rope for serface area grip ?

[Tank]

Bush - So are you saying that with hand winches they need a bigger rope for serface area grip ?
No they dont, you can get Tirfors with 10mm rope, your Tirfor has a RATED SWL or WLL of 4.8T so the cable is of a size that will comply with the rated SWL, Regards Frank.