Polypro rope woes

[mikeyT]

Last evening I was over at my brother's place to help him extract a stump. Warn HS9500i, polypro rope.

I set up for a simple straight pull from about 40' away; tree strap, shackle, blanket on the rope, not rubbing anywhere. My truck was butted against a good size maple to keep it in place.

We stood back out of harm's way, just in case, as should be done.

On the very first pull, with the stump budging a bit at least, the winch got almost to the stall point when the line snapped at the winch. That thing recoiled like a bullet into the blanket. I was astounded; those ropes are supposed to be load rated pretty highly. And, according to urban legend, they're not supposed to recoil dangerously like that.

This was a relatively new rope, placed on just one year ago, maybe a couple dozen pulls "under its belt". It spent the winter on the truck, but covered, well protected from the elements.

During the first time pulls with the rope. We (Steve and Brad Morris and I) found it slippery; it kept sliding on the spool and pulling out of the anchor lug. That was fixed by sticking an 8" x 8" piece of skateboard grip tape to the spool. THAT worked great last night. If it had have slipped, I'd still have a rope. Also, the rope deforms easily, sinks down into the wraps easily; but this, apparently is normal. But all this led to Brad not really liking the rope. So now, I'm in agreement. Just as well it broke under simple conditions; I'd rather not have it break when I have a buddy on the end of the line (facing uphill, off-camber, something like that).

Cheers.

I'm off to the wire rope store.

[chet]

I have synth rope as well. and it still recoils but with it being so light there is no force behind it. If it did hit you it would leave mark but yu would be OK if it was steel cable it would cut you in half! Strange that it broke where it did. I have had good success with mine.

[lowenbrau]

You don't really mean Polypropylene do you? The only Rope I know of that exceeds the strength of wire rope is HMWPE (high molecular weight poly ethylene) I have the Amsteel Blue version and am happy with it. It is easy to splice once it breaks. All the breaks I have seen have had little drama. What brand/size of rope are you running?

[mikeyT]

Hey, Bruce.

I bought my rope from Rockstomper. It is the Amsteel Blue stuff. I thought it was polypropylene. Polyethylene; I stand corrected. Here's a link to the manufacurer's write-up, via Rockstomper:

http://www.rockstomper.com/images/pr...pe/amsteel.jpg

It's 5/16ths and 125' long, supposed to be the best. Rated 13,700lb at that size.

I've however just lost confidence in it; maybe I'm over-reacting...

I put a huge load on it, but slowly, without bucking the control, didn't pull with the truck, no rubbing anywhere. I figured that winches don't really pull with their full rating and the rope is supposed to easily withstand a straight line pull. And the story about no recoil is clearly not realistic.

Cheers.

[mikeyT]

Chet, your point about the actual dangerousness of the recoiling synth rope are surely valid. Makes sense; it doesn't have nearly the mass of a wire rope nor the "cutting/sharp edge" factor.

Cheers.

[lshobie]

Hi Mike, If the rope was only rated to 13.7K or so - then it wouldnt take much to take it to it's failing point. Any minor chaffing, or pinching point could have caused it to go - especially if your winch was rated at 9.5K pounds.

We had a hook snap on a wire winch cable once, nearly tore the windshield frame in half on my buddies fj40.

REgards

[mikeyT]

I've had some time to think about this, Lou. When I first installed the rope a year ago, it would slide on the spool and pop out of the eye-grommet. It did that about 3 times. All the same, I managed to get a couple dozen good pulls out of it during one memorable off-road event.

(Down in New Hampshire at the Yankee Toys' Fall Gathering, one of the guys broke his rear drive shaft, so, since I was in front of him, I got to break in my new winch. At one very interesting point, we did a dozen pulls, at least, to winch him uphill over slick boulders in the dark. I actually had to climb the hill in reverse. The Morris' did the spotting, cable-monkeying and controlling. I followed orders.)

Because of that slipping on the spool, I got the skateboard grip tape. An 8x8 piece stuck on the spool seemed to do the trick.

HOWEVER, I think maybe the rope bit down through the wraps right to the grip tape and was abraded enough to cause it to fail.

Cheers.

[crushers]

i must be damn lucky, i have broken many steel winch cables under extreme load and NEVER had so much as a recoil let alone it coming back visiously.
every single time all it does is travel about 2-3 feet and drop...

i would love to see a test of stored energy in a steel cable under say 14,000 lbs of pull...

anyone have some links to actual tests?
cheers

[HZJ60 Guy]

There is a video out there somewhere of a guy getting cut in half by a broken winch cable. It was horrible. I watched it before I really knew what it was. Very serious and very dangerous.

[crushers]

i would be more cautious around a tugem than a winch cable...
it would be interesting to know the whole story behind the clip you watched to see if there were any other extenuating circumstances...
cheers

[lowenbrau]

Neither wire rope nor synthetic rope stretch much. This makes them very bad for rock climbers to use. It also makes them a poor choice for towing with. Tuggum straps are opposite, they stretch a whole bunch, store a lot of energy and smoothly take it from a moving truck and apply it to a stuck one. If a tuggum strap fails, it recoils with much violence. If a rig has its winch securely mounted exactly at its center of gravity, on level ground, and pulls perfectly straight on, a broken cable drops immediately to the ground. I can hear some of your eyes rolling now, hear me out... A winch cable will recoil when whipped by the loaded suspension of whichever rig it remains connected to after it breaks. There is lots of science showing that in a controlled test facility cable fails very anti climatically but the news reports show cable failing violently. The difference is if/how you store energy. A tow truck, winching from the top of its boom to lift a wreck from a ditch can easily lift its front wheels off the ground. If that cable comes loose from the wreck the cable can be whipped exactly like a bull whip and it will take the cab of the tow truck off. Its documented and has happened in BC. I carry about 225' of amsteel blue on my winch and it weighs four or five pounds. It replaced about 50 lbs of wire rope. If my winch technique causes my rig to whip the cable, I feel a lot better about being struck with four lbs of plastic even if it is doing 90 MPH.

[Mark W]

Ditto what Bruce says and Wayne alludes to. Neither wire or synthetic winch cable/rope stores much energy and neither cause any significant recoil. It is chain and hooks and (if you're nuts) snatch straps rigged to the cable that create the recoil due to the energy that they store as they stretch and deform and then release when the fail. Compressed suspension of the rig, a flexed boom on a wrecker and lots of other things can store energy and cause recoil when some thing in the rig fails. But the cable or the rope is not the culprit. I've broken my share of cables in the field and watched a few purposely stressed to the breaking point in a test stand. Anyone who tells you that the cable is the cause of the recoil has not examined the situation closely enough. The real cause will be found elsewhere.


Mark...

[Greg_B]

Very interesting. Thanks all...

gb













































Call me post whore tonight...

[mikeyT]

Originally Posted by Mark W

Anyone who tells you that the cable is the cause of the recoil has not examined the situation closely enough. The real cause will be found elsewhere.Mark...

That's it. You guys are right. In my case, the stump had lifted an inch or so, and being nice massive (and stuck) green wood, it flexed and IT returned to its original resting state, whipping my rope towards it. The wrecker analogies illustrate this effect very well. Thanks.

Cheers

[mikeyT]

Anyone have any better ideas for keeping a synthetic rope from sliding on the spool? I found the skateboard grip tape idea searching Pirate, IIRC; I'm almost convinced that that caused the rope to fail. Before the tape, the rope would slide and pop out of the anchoring eye-grommet thing, did it 3 times despite at least 2 layers of rope still on.

It certainly held the rope in place for this last pull, though.

TIA

[mikeyT]

So. As it happens, I'll get to test my rope again. About 30' had snapped off, leaving me with about 95' of rope. A friend in True North is a sailor and is quite experienced in splicing lines. He'll fix the new end of rope so I can replace the hook and put a new loop on the broken length so I'll have an extender strap.

To be continued next pull...

No more stumps, though.

Cheers.

[Kalawang]

Kind of shocking to hear that the rope snapped and whipped. Now I don't know what to trust.


Kalawang

[lowenbrau]

I'd just end splice the break and put it all back on the drum if I were you. Some guys are putting climbing webbing over the rope for abbrasion and UV resistance. Maybe you should leave the griptape on the drum but add enough webbing for the bottom wrap.

3/4" tubular webbing

[wesintl]

Not to hijack but there is a 24v 8274 on ebay. Some 24v dieselers might be intersted in.

[honk]

Since it squeezes down into itself (for lack of a better way to put it) doesn't it make sense to use a larger size than the wire it replaces? The strength rating jumps pretty good going from 5/16" to 3/8" and most any winch spool has room to have the same length of fiber rope in a larger size as there's room for with the smaller wire cable. Bigger rope = more safer stump pulling, no?

[mikeyT]

I agree with you, honk. After all consideration of the situation, I remain convinced that the synthetic rope is far safer. If I was to replace it, I'd go with 100' of 3/8ths and use an extender rope made of the same material.

As it is, there is almost 100' of 5/16ths remaining on the spool, so I'll keep that, get it re-spliced and make the extender out of the length that snapped off. A buddy of mine is doing the splicing; I'll let you all know how it goes.

When THAT snaps, I'll go for the 3/8ths.

Cheers from humid Ottawa.