Haul Rope Stretching

TomWhite

I remember Mt. Snow’s Challenger Triple had an unusually long stretch in its haul rope. I don’t know if it was the first season, but I remember the spring photo, with much snow and a full-size bulldozer being used in the repair process. My question for the experts is, what is the normal number of shortening and resplicings a haul rope can endure? I’m guessing two. What is the average life span of a haul rope? I’m guessing age, seasons of hot and cold, are at least as important as hours of use.
Below is a bit of Liftblog’s posting of Sunshine’s work.

sunshinevillage

So what is a gondola splice? The haul rope is the backbone of a gondola system. It’s the continuous steel cable that runs in a loop, pulling cabins up and down the mountain. Over time, the rope can stretch slightly due to regular use, tension, and environmental conditions. This stretch, while completely normal, must occasionally be corrected to maintain optimal tension and performance.

That’s where splicing comes in.

Jonni

While I'm not an expert on it, when I worked at Sunapee on lifts, we had to resplice our Sunapee Express once during the time I was there due to stretching. We removed about 25' of rope during that splice and it was a very interesting process to be involved with. The lift was built new in 1998 and is around 6100' long. I'm also pretty sure it was respliced within a year after install due normal stretching that happens within the first year.

That being said, the old Sun Bowl Quad (the fixed grip lift) that was replaced in 2014 had had numerous splices in it due to the lift moving many times in it's lifetime. It started as the Solitude Quad at Okemo, then was the South Face Quad, then moved to Sunapee as the Sun Bowl Quad. Each time it had to have a resplice, in addition to the normal 1 year post original installation resplice. We also respliced that rope in the same year as the Sunapee Express due to availability of the guy splicing the express. That haul rope had many MANY hash marks for the years of grip movement. If the history serves me right, that's 5 splices on that lift over it's 38 year life. Pretty sure that rope is still spooled up at the bottom of the Sun Bowl.

LiftGuy

Good questions, Tom. In reality, there is no limit to the number of 'resplices' that can occur. The 2 most common reasons for a resplice are 1) To shorten the rope to restore carriage travel and 2) To eliminate broken wires in the splice zone. The amount removed during shortening is limited to the amount of carriage travel available x2 minus an amount for rigging for the splice. In Jonni's example above, I'm guessing they had 15' of carriage travel (30' total) minus 5 ' for rigging= 25' removed.
Rope stretch is a function of its construction process, and the process of pre-tensioning during construction and the use of solid poly cores has greatly reduced the amount of initial stretch. It is also affected by the length- more rope=more stretch. The original American Flyer at Copper Mountain, CO with just under 20,000' of 42mm rope was re-spliced 3 times in the initial season.
As for life span, a properly maintained wire rope should be able to last for 25-35 years of normal operation. Obviously, a lift that runs on a limited schedule of reduced hours or extended hours will differ. The most common reasons for replacement are 1) loss of diameter (which is usually an indication that the fiber core is collapsing and no longer supporting the strands properly) 2) loss of metallic cross section (too many broken wires in a given section or too much crown wear caused by grip slippage or continuous contact with sheave or bullwheel flanges.
Hope this answers your questions.

TomWhite

Thanks LiftGuy, that's a lot of helpful information. On occasion we do see haul ropes having to be respliced during the season. I've presumed that carriage travel has reached its limits. Obviously, areas prefer to do this work in this off season. I've never thought about decreased diameter as part of the stretching/aging process.
Another question occurs to me. Do detachable lifts generally have less "ability" for carriage travel?

LiftGuy

Detachable lifts and newer fixed grip lifts are hydraulically tensioned and therefore are limited in carriage travel by the length of the hydraulic ram used. Provisions can be made to add extensions to the ram travel with the ability to isolate the carriage to move the extensions. LPOA also has passive tensioning (the terminal can be moved and then locked in place) in the terminal opposite the active tensioning, which give additional ability to adjust for rope stretch. I'm not sure if Doppelmayr also has that function.
Older fixed grips were tensioned by physical counterweights and the amount of carriage travel is determined by the length of the structure supporting the carriage.
Each lift is required to have a Wire Rope Log which includes splice data and annual inspection reports that should include relative carriage position, which should preclude mid-season resplices. Those are generally caused by extenuating circumstance.

TomWhite

All cool stuff, thanks.

obienick

Correct me if I'm wrong but don't most of mid-season re-splices occur on first-year lifts?

When I was living in NY Greek Peak had to replace 1A after a month or so of running and had to replace it again that summer.

LiftGuy

obienick;c-69423 wroteCorrect me if I'm wrong but don't most of mid-season re-splices occur on first-year lifts?
When I was living in NY Greek Peak had to replace 1A after a month or so of running and had to replace it again that summer.

You are correct. The majority of constructional stretch occurs in the first few years of operation. Looking at 1A at Greek Peak it seems to have shorter terminal travel and a shorter hydraulic ram which would contribute to the initial 2 re-splices.

ceo

LiftGuy;c-69334 wroteLPOA also has passive tensioning (the terminal can be moved and then locked in place) in the terminal opposite the active tensioning, which give additional ability to adjust for rope stretch. I'm not sure if Doppelmayr also has that function.

Poma detachables have this weird arrangement where the entire terminal can move back and forth on its supports. I'd wondered why they're like that at both ends; now I know.