38 replies to this topic

[pete_dl]

What is an average expected lifetime of a haul rope ? I imagine it varies considerably, but I just want a rough idea.

Thanks,
Pete.

[Aussierob]

About 20,000 hours. Sometimes more.

[towertop]

Many factors... but the biggest would be when the person who inspects your rope says it's at the end of its usefull life. I have seen ropes go way past 20,000 hrs and have seen them go less. If you take care of the rope by doing the required inspections and maintenance, you can expect many years of use. Also the length of a rope should be taken into consideration. A short rope that will have many cycles won't last as long as a rope thats longer.

[pete_dl]

20,000 hours sounds surprising short (in my ignorance). What is the fastest type of deterioration ? Fatigue, abrasion, or weathering ? With a 6 times safety factor I would not have thought that fatique is a problem.

Pete.

[aug]

Min. diameter ,excessive lay length

[Vinny 2 Shoes]

How much do ropes usually cost/unit length?

[pete_dl]

aug, on Mar 12 2009, 10:41 PM, said:

Min. diameter ,excessive lay length

Interesting. By this I am guessing you mean that the rope stretches over time. The temperature required for steel to creep is greater than 300 degrees C, so what is happening ? Does the weave of the rope flatten/stretch ?

[aug]

pete_dl, on Mar 13 2009, 10:01 AM, said:

Interesting. By this I am guessing you mean that the rope stretches over time. The temperature required for steel to creep is greater than 300 degrees C, so what is happening ? Does the weave of the rope flatten/stretch ?

The core is wearing out making the diameter smaller and the length longer. Steel expands and contracts with tempreture . I expect the tension carriage to be in different postions vs. a hot day and cold day. I believe this is due to the thermal expansion/ contraction of the steel. ( Please correct me if I am wrong). As for the Lay length and Diameter of the rope, as the rope ages under tension and use, the core "breaks in " lengthening the rope . This is why in the past (before solid core ropes) that a resplice was usually needed in the first years of the lift with a new haul rope. As the core wears the strands of the rope come into contact with each other. The result of this is called "nicking". The wire in the strands( inside the rope) will show were wire to wire contact is being made. (Splicer should post a link to a wire rope page.)Hope this helps

This post has been edited by aug: 13 March 2009 - 09:47 AM

[Kicking Horse]

I once heard that the avg detach haul rope service life is ~30,000 hrs.

[Splicer]

Okay here it goes:
In general, and ignoring the very lift-specific detail parameters, revolving "average" haulage ropes on "average" ski lifts serve some 20 years on fixed grip lifts, that a running at 400 fpm.
Rope life is based more on rope cycles, bending cycles around the bull wheels and cycles over the sheave assemblies rather than number of years on the rope.
With a range of 90,000---120,000 expectable rope cycles, the speed, the length of the lift, and the number of service hours are decisive for a rope life expectancy:

Example: "average" lift length 4000 ft.
rope length 8000 ft.
"average" lift speed 400 fpm 1000 fpm
rope cycles per hour 3 7.5
rope cycles per ski season (1200 hrs) 3600 9000
min. expectable rope life 25 seasons 10 seasons
max. expectable rope life 33 seasons 13.3 seasons


This does not consider outside influencing factors such as routine maintenance (how often the rope was lubed), quality of the rope, quality and condition of the splice, if the rope was initially installed correctly, as well as the drive and line machinery quality (proper alignment), all of which contribute to the life expectancy of the rope.
Calculating Cycles Per Hour

Rope Length = 8000 ft.
Lift Speed = 1000 fpm

1000 fpm/ = 1 ft./min./ = 1 cycle / X 60 min. / = 7.5 cycles/
8000 ft. 8ft. 8 min. 1 hour hour
divide by
1000 to
simplify

Rope Length 8000 ft.
Lift Speed 400 fpm

400 fpm/ 60 min /
8000 ft. 1 hour

Divide rope speed by lift length then multiply by 60 = cycles per hour.

I couldn't figure out the underline for divided by so the "/" will have to do. ex. 1000fpm/8000ft. in the example above.
In my experience in inspecting wire rope, lay length and diameter generally never are the cause for rope retirement, the most common cause for rope retirement is the splice where work hardening makes it no longer possible to splice the rope. Hope this helps in this discussion.

Attached File(s)

•  Rope_Life.pdf (27.85K)
  Number of downloads: 61

[Kelly]

Norm thanks for the detailed explanation.
I will second the cycles around bullwheels for wear is very valid…changed a haulrope every three years for nine years on a 700’ Chair – night skiing plus first to open and last to close.

[liftmech]

....and on the other end of that spectrum we have an original 1986 42mm rope with 29,000 hours on it. It's almost 20,000 feet long, though, so the cycles are way lower than you'd expect.

[Kicking Horse]

So Longer the Rope the longer it will last? Interesting. Never knew that.

[FSJ]

Kicking Horse, on Mar 19 2009, 06:55 PM, said:

So Longer the Rope the longer it will last? Interesting. Never knew that.

Length and speed. Twice as long and twice as fast would have the life, not including other factors as mentioned above.

Similar with insert clips. Inspection & relocation intervals should be determined more by cycles around the bullwheel than just straight operating hours.

[moura39]

I WOULD LIKE TO KNOW IF A CYCLE IS A COMPLETE RETURN OR TOP-STATION TICKET IN THE BULLWHEELS (A COMPLETE RETURN AND TOP IS THE TWO BULLWHEELS, HOW MANY CYCLES IS?

[Bogong]

The First Doppelmayr double chair in the world had the same haul rope for it's entire life, from 1964 to 1983 at Mt Buller in Australia. The cable came with a 20 year guarantee and despite constant inspection and testing, it never needed to be replaced.

[moura39]

HOW MANY CYCLES ARE IN A COMPLETE RETURN WITH TWO BULLWHEEL? (intervals should be determined lives by cycles around the bullwheel than just straight operating hours)

[Lift Kid]

moura39, on Mar 25 2009, 09:31 AM, said:

I WOULD LIKE TO KNOW IF A CYCLE IS A COMPLETE RETURN OR TOP-STATION TICKET IN THE BULLWHEELS (A COMPLETE RETURN AND TOP IS THE TWO BULLWHEELS, HOW MANY CYCLES IS?

Although I'm not certain about the question you are asking, I think I might understand it a little. One cycle is the cable going uphill and coming back downhill. So it goes around both bullwheels to be a complete cycle. Hope that helps.

[moura39]

Although I' m not certain about the question you ploughs asking, I think I might understand it little. One cycle is the wire going uphill and coming back downhill. It goes around both bullwheels you be only completes it cycle. Hope that helps. OK WILL BE TRUTH THAT COUNTS ONE OR TWO, HAS THE CERTAINTY?

[2milehi]

The Outpost Gondola at Keystone has ~45,000 hours on it. I believe that it is the original rope, but I will double check this.