Wire rope splices: Ski Cooper, A-Basin

[BushMogulMaster]

Is there a different splice and/or tuck technique used on haul ropes for detachable systems? The reason I ask is because where I work (with all FG chairs) we're told to make sure none of the grips move (the grips move back slightly when they go around the bullwheel and can move quite a bit over the course of a season) onto any of the tucks because it could damage the tuck. With a detachable it seems there would be no way to make sure the grip didn't re-attach onto the haul rope where a tuck was.

The technique is basically the same, but detachable lift tucks must be tested to a certain compression tolerance via a hydraulic press.

The technique of tucking varies much more based on the wire rope manufacturer (not the lift manufacturer, although sometimes they are the same). For example, at the Cooper splice, the wire rope manufacturer didn't specify tail length. However, on the A-Basin splice, the manufacturer specified 8' tails. Things like that will vary from splice-to-splice.

What you're referring to in your question is called grip migration in fixed grips. That fixed grip is pretty tight, and if it migrates onto a tuck point, it's not only compressing the tuck (which isn't a big deal.....), but it's also applying a "pulling" force on those strands that have been tucked. A detachable grip wouldn't do this, because when it "re-attaches," it just grabs and doesn't pull any force on the individual wire rope strands.

 

[BushMogulMaster]

Not a problem. I had a feeling that's what they'd use. It makes sense. I guess it's sold as both Spectra and Dyneema in stranded form.


Incidentally, it's technically the same base molecule that makes up what milk jugs are made from (HDPE).

So just remember, you're trusting your life to a milk jug rope....

:dunce:

:lol:

Yes, but there's no tensioning force really acting on said milk jug material. It's the six strands that take care of that. The milk jug just gives them their shape. :wink:

 

[Marc]

Hey Mr. Brains, a simple "Cool, thanks for the pictures." would have been enough.

So i'll dumb the thread back down and ask, how much weight can a cable like that take?

Hush up boy, so's I can learn ya somethin'.



According to Harken, stainless braided rigging 1/2" in diameter has a breaking strength of 30,000 lbs.

These haul ropes are, what BMM.... 1 1/2" - 2" diameter? I'd imagine the breaking strength has got to be on the order of several hundreds of thousand pounds or possibliy a million pounds (500 tons) or more.

 

[Marc]

:lol:

Yes, but there's no tensioning force really acting on said milk jug material. It's the six strands that take care of that. The milk jug just gives them their shape. :wink:

Shush. They don't know that. 'Specially kore... that boy's just a few sandwiches short of a picnic, if you know what I mean.

 

[koreshot]

I assume those properties remain pretty much constant between -50F and +150F.

Another dumb question, how many occurences of chair lift cables breaking are there? This does not include freak accidents involving incompetend US military pilots.

 

[Marc]

Actually it wouldn't matter even if it did. Spectra is still incredibly strong. While 1/2" stainless breaks at 30,000 lbs, Spectra will do almost as much... 27,000 lbs at the same core diameter. So basically, it's as strong as steel.

 

[bvibert]

The technique is basically the same, but detachable lift tucks must be tested to a certain compression tolerance via a hydraulic press.

The technique of tucking varies much more based on the wire rope manufacturer (not the lift manufacturer, although sometimes they are the same). For example, at the Cooper splice, the wire rope manufacturer didn't specify tail length. However, on the A-Basin splice, the manufacturer specified 8' tails. Things like that will vary from splice-to-splice.

What you're referring to in your question is called grip migration in fixed grips. That fixed grip is pretty tight, and if it migrates onto a tuck point, it's not only compressing the tuck (which isn't a big deal.....), but it's also applying a "pulling" force on those strands that have been tucked. A detachable grip wouldn't do this, because when it "re-attaches," it just grabs and doesn't pull any force on the individual wire rope strands.

Thanks, makes sense. I guess the detachable grip doesn't pull on the strands because it never goes around the bullwheel with the haul rope where it flexes the most?

 

[BushMogulMaster]

Cool. Could you give some background for those of us who don't know anything about operations? Why would you splice a haul rope? Was the entire rope replaced?

Sure. Let's start with reasons to splice a haul rope (which has sort of been answered already).

Of course, any new lift installation will require a splice, because the haul rope comes as one long rope, not a continuous rope (aka, it has ends). So in order to make it a circulating haul rope, it's gotta be spliced together. The A-Basin splice was a splice of a brand new Poma fixed grip quad.

Another reason is stretching. Over time, with the incredible tension on the wire rope, it will stretch and require a splice.

Finally, eventually, a haul rope will stretch so much that it will begin to lost diameter (because the tension causes the strands to compress the core). In this case, simply splicing the existing haul rope won't suffice. Therefore, a new wire rope must be purchased, and then spliced just like on a brand new lift.

As for the process, I'll try to keep it concise, but it's a very very complex process when you get down to the details.

Basically, you have your haul rope detensioned on the towers, and you pull down a segment of the haul rope. You determine the length of the splice by multiplying the diameter of the wire rope by 1,200. That's how much you're going to work on.

You then need to mark 6 points (assuming a 6 strand rope), the end points being the far ends of the length of the splice, and the remaining 4 equidistant between them. Remember... at this point, there are two distinct ends of the haul rope, because it is not a continuous loop yet. The marriage (more on that in a minute) occurs at the center point of the splice length.

At those 6 points, a stake is pounded into the wire rope to separate a single strand, which is then "cut" with a welder. That strand is unwound from the outside toward the center of the splice length. Therefore, you unwind three strands from uphill of the center point TO the center point, and three strands from downhill of the center point TO the center point. (important but confusing detail: the 3 strands you unwind from downhill are on the segment of wire rope whose end also terminates on the downhill side. this will make a little more sense later. essentially, this piece of haul rope originates from a sheave trail uphill of the center point, and terminates downhill of it, and then is unwound UPHILL to the center point)

Once that's complete, the marriage must happen at the center point of the splice length. The three unwound strands are pulled away from the three wound strands and the core. Using the welder, the wound strands and core are cut off. Repeat the process for the other side.

The marriage itself is way too complicated to explain in this setting. Suffice it to say that the strands at the marriage point are twisted and combined, all the while pulling on the strands that were separated, while the splicer pounds and combines the strands and cores until that marriage point looks essentially the same as any other point on the wire rope.

So you have to visualize what it would look like at this point: the marriage point, three long strands going uphill from the marriage point, three long strands going downhill from the marriage point, one complete six strand wire rope going uphill from the marriage, and one going downhill (see the "important note" above if you're confused at this point).

Now you measure out the separated strands (minus tail length) and mark on the intact wire rope where they will wind to. Then, one at a time, unwind a strand to the point associated with the strand you plan to wind, then wind the new strand. The freshly unwound strand is cut off via welder, leaving the tail length behind. As you do this, the splicer is pounding it in with metal mallets. You do this 3 times downhill, and three times uphill.

Once that is complete, it's time for the tucks (one where each tail ends). At each tuck point, you have 2 tails: one from the freshly wound strand and one from the freshly unwound strand. Those strands are wrapped with a rubbery material until they are equal in diameter to the core. The core is removed for the length of the tails, and the tails are "wrapped" into the wire rope and become the core for that segment. You pound the tuck point, and you have a successful tuck. Repeat for the other 5 tuck points, and now you have a spliced wire rope.

I left out some details, but the explanation was long enough already!

 

[BushMogulMaster]

Woah... nice pictures... thanks BMM. I've always wanted to see that done. Apparently it involves much fewer big tools than I thought it would. Looks like it's mostly hand tools and man power. Very cool.

Yeah... not really much for tools going on. A couple of spikes, a few mallets, a welder, a heat gun, and someone who's been working splices for years. That's all a basic splice requires.

 

[BushMogulMaster]

I assume those properties remain pretty much constant between -50F and +150F.

Another dumb question, how many occurences of chair lift cables breaking are there? This does not include freak accidents involving incompetend US military pilots.

The only occurrences I'm aware of were heat related. If there's a fire and the haul rope is stationary, it WILL compromise the integrity of that point until it breaks. Bad news releasing a few tons of tension all at once.

 

[BushMogulMaster]

The splice is where the two ends of the haul rope are attached together. To my knowledge it's only done when replacing the haul rope, you wouldn't splice in a section for any reason.

I've always wanted to see how it was done myself.

Is that you with the Sugarbush vest on BMM?

Yup. Gotta sport the Sugarbush colors!

 

[BushMogulMaster]

Hush up boy, so's I can learn ya somethin'.



According to Harken, stainless braided rigging 1/2" in diameter has a breaking strength of 30,000 lbs.

These haul ropes are, what BMM.... 1 1/2" - 2" diameter? I'd imagine the breaking strength has got to be on the order of several hundreds of thousand pounds or possibliy a million pounds (500 tons) or more.

They're typically measured in mm. They generally range from 25-60mm, depending on lift type, length, tension, etc. I believe the wire rope we spliced at Cooper was 36mm, and the one at A-Basin was 40.5.

So yeah, you're range is pretty close in inches.

 

[BushMogulMaster]

Thanks, makes sense. I guess the detachable grip doesn't pull on the strands because it never goes around the bullwheel with the haul rope where it flexes the most?

Yes. A fixed grip going around the bullwheel creates a lot of forces on the haul rope other than straight tension force. Doing this on a tuck point (where the two tails are twisted and unwound) would be adding undue force to a point that MIGHT be slightly more easily compromised.

It would still probably take a long time for a serious problem to arise, but if it did... you'd have problems!

 

[BushMogulMaster]

Not a problem. I had a feeling that's what they'd use. It makes sense. I guess it's sold as both Spectra and Dyneema in stranded form.

BTW, the polyethylene cores are not stranded. They're a solid wax-like core.

 

[BushMogulMaster]

Here are two pictures of the marriage:

 

[Marc]

Little early in the season to break out the Koflach's isn't it?

 

[sledhaulingmedic]

The technique is basically the same, but detachable lift tucks must be tested to a certain compression tolerance via a hydraulic press.

The technique of tucking varies much more based on the wire rope manufacturer (not the lift manufacturer, although sometimes they are the same). For example, at the Cooper splice, the wire rope manufacturer didn't specify tail length. However, on the A-Basin splice, the manufacturer specified 8' tails. Things like that will vary from splice-to-splice.

What you're referring to in your question is called grip migration in fixed grips. That fixed grip is pretty tight, and if it migrates onto a tuck point, it's not only compressing the tuck (which isn't a big deal.....), but it's also applying a "pulling" force on those strands that have been tucked. A detachable grip wouldn't do this, because when it "re-attaches," it just grabs and doesn't pull any force on the individual wire rope strands.

Help me out here, cause I'm the dumest guy in the world: I thought the elength of the splice was set ANSI B77 at something like 1200 or 1700 times the diameter of the wire rope?

 

[BushMogulMaster]

Help me out here, cause I'm the dumest guy in the world: I thought the elength of the splice was set ANSI B77 at something like 1200 or 1700 times the diameter of the wire rope?

Total splice length is 1200 X diameter, yes. Tail length is a completely different thing.

 

[mountainman]

Who did the splice?

Now few guys who do them in the east. Just did a cable shorting at the resort i work at. Done a few spilces in my days. Did one in Dec. in the east not fun. Looks like you had good weather for it. Makes a big difference.

 

[BushMogulMaster]

Now few guys who do them in the east. Just did a cable shorting at the resort i work at. Done a few spilces in my days. Did one in Dec. in the east not fun. Looks like you had good weather for it. Makes a big difference.

Who did the splice? Dale Walters? Alsop (can't remember first name... is it Bill?)?