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How Does A Chairlift Work?

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HOW DOES A CHAIRLIFT WORK?

BY, DEE DEE TOMATOS AND ANDY JAMESON

Wait your turn, lower the bar, quickly judge if the people next to you are friendly enough to converse with, and that’s it, nothing to it.  The chair magically sends you to the top of your run.  Easier than hiking, cheaper than a helicopter, and a lot more quiet than a snowmobile, it’s no wonder chairlifts are the most popular uphill people mover.   But how do they work?  Below we walk through the basic mechanics of the two most popular types of chairlifts: the classic fixed grip, and the high speed detachable.  Most other lifts are variations of these two technologies.  Special thanks to Chairlift.org for technical knowledge and pictures.

The Classic Fixed Grip

If you’re old enough to (legally) drink a beer, you’ve spent a good amount of time ridding the classic fixed grip chair.  Save Magic was kind enough to supply us with some background on Magic Mountain’s 1971 Heron-Poma fixed grip double chair, which we’ve used as an example.   We are going to really simplify the process for those who never think about what they are riding.

A chairlift is basically a looping steel cable with a large pulley at each end (the bullwheels).  Carriers (the chairs) are hung from the cable and held in place with a mechanical grip.  The grip functions similarly to a vice and is tightened around the cable to keep the chair from sliding back.  A chair gradually slides back a bit each season, which is why lines are often painted on the cable.  The paint mark provides the lift mechanic with a visual indicator of how far the chair has moved.  Don’t worry if the paint mark is far away, chairs are often moved every few seasons to ensure even wear on the cable.

                         Positive Jaw Grip                                                         The Red Chair’s Summit Bullwheel

A series of towers form the line and keep the cable from dropping to the ground below. Towers are installed with either a crane or a helicopter depending on the budget, terrain, and weather.  The towers are topped with cross-arms that hold sets of wheels called sheaves.  The cable can go either above or below the sheave assemblies. On the vast majority of towers the cable travels over the sheaves, exceptions are when the lift is about to climb a steeper section, traveling under adds tension to the cable allowing it to achieve a more drastic angle.

                     Cable Traveling Under Sheaves                                                 Helicopter Installing a Tower

So what makes the bullwheel turn?  Today most lifts are driven by electric motors but have secondary diesel backup drives.  Mad River’s single chair ran exclusively on diesel until 2007, when it was completely refurbished.  Today’s electric motors are cleaner and less expensive than their diesel ancestors.  Chances are if you hear an engine running, the lift is operating on its back-up diesel for one reason or another.  The engine can be located at either the summit or the base of the lift depending on the engineer’s recommendations.

What keeps the cable from getting too loose? On older lifts a large counter weight provides tension to one of the bullwheels, ensuring that the cable remains taught.  Newer lifts use hydraulic tensioning (giant shock absorbers) for easier adjustability and improved ride quality.

        Red’s Counter Weight Sits on Railroad Tracks       Modern Hydraulic Cable Tension System

Magic’s Black Chair has a highly visible summit counterweight. 

 

The High-Speed Detachable

We all know that high-speed detachable chairs are much faster, and as the name implies, the chair “detaches” from the cable.  In fact, high-speed chairs are 2.4x the speed of their fixed grip brethren.  These detachable chairs typically travel at speeds of 1,200 feet per minute (14 mph, 22 km/h, 6 m/s) versus a typical fix-grip speed of 500 ft/min (6 mph, 9 km/h, 2.5 m/s).   Theoretically, a fixed grip chair could move just as quickly; however, getting off and on a chair traveling 14mph could be very painfull and embarasing.

High-speed detachables work in a very similar manner to fixed grip chairs, with one key exception. The high-speed detachable has a grip mechanism that allows the chair to release from the cable at the loading and unloading stations. The cable continues to run at the faster speed while passengers load and unload at easy slow speeds reducing the number of stops the lift must take.

To detach or not to detach?  Traditionalists favor the fixed grip for many reasons.  Fixed grip lifts are well suited to service tougher terrain where the capacity of a high speed lift is not necessary.  They provide more time for recovery and plenty of time to chat with your neighboor, enjoy a beverage or whatever else suits your fancy.  Most importantly, powder is not tracked out as quickly.

In the West detachables are a treat as there is much more acreage over which to dispense skiers.  Resort designers in the East must carefully consider where to place detachables and and how they affect skier traffic.  Detachables also help get new skiers using lifts quicker as loading and unloading is almost at a standstill.

 

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24 comments
  • Miles Clark (the real one)

    FYI
    Not all fix grip chairs are clamped. Some are head in place by tension from the haul cable. A tongue on the chair is inserted between the cables that become the main cable once it is spliced together and weighted by the counter weight.

    • Dee Dee

      Agreed Miles, we love Riblets with clips as well but figured we would keep it simple for the beginners.

      Mabey a follow up story!

    • Art Vandelay

      I guessing you haven’t skied at any of the rinky dinky ski areas across the east. Riblet chairs are all over out there.

      • Anonymous

        Riblets are almost all gone in the east, most remaining old school chairs are Halls or Borvig in the east. You actually see many more Riblets in the west and PNW.

  • Goose

    The speed of a chair has absolutely nothing to do with uphill capacity. Chairs unload every 6-8 seconds on the average chair, fixed grip or detachable. Capacity is based on number of seats per carrier and the frequency of the chairs, not the speed of the rope. A fixed grip chair has 2.5 times more chairs on the line but moves 2.5 times slower.

    • Anonymous

      frequency of chairs=speed of chair / distance between chairs
      therefore, speed of chair does matter. Because detachables improve loading/unloading efficiency, the distance between chairs can be kept more or less constant for fixed grip vs detachable. As a result, uphill capacity is improved.

  • SkiPhan

    Do I really need a lesson in this. I’ve stared at countless lifts over the years, I think I figured it out, just by observing.

  • Anonymous

    Holy fuck is it hard to be appreciative of an article every now and again? Cheers for the article. As for everyone else quit Internet trolling.

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  • BoGnar

    How a chair lift works

    Your buddy is falling asleep in a chair. You and your buddies notice this and position yourself besides the chair.
    This is a plastic lawn chair. You grab the back legs and lift. Your buddy meets the lawn with his face and crushes his half drank beer under himself.
    Everyone gets a good chuckle.

    Note: this only works with good friends. Do not try with strangers!

  • Chris

    All pretty accurate except for, ” Chances are if you hear an engine running, the lift is operating on its back-up diesel for one reason or another.” This isn’t true. The back up diesel is run everyday to keep it operating correctly. It is not attached to the drive gears at this point so it runs concurrent with the electric motor. In other words, if you hear a engine running, it most likely is just sitting staying warm like every other day.

    • liftie scum

      the diesel is usually only run for 10 mins before opening to public, unless electricity use allowances are exceeded. if its running during normal operating hours, theres an issue.

  • CalSki

    Long live the fixed grip. Those darn detachables go too fast to enjoy a fat one on the chair. Can’t even light the darn thing, then when you do it runs to high heaven, ruins the dube.

  • Phil

    A detachable high speed lift can change the dynamics of a ski hill. The older fixed grip chairs become less attractive and don’t run midweek anymore, because the high speed is so popular.

  • Per-Ola

    Miss the detachable “Poma” surface lifts – or what we call the button lifts in NA. They were used a lot in France to reach odd but good terrain. They were very fast, and they kept the beginners out of the way. You learned to stand sleeping while they whisked you up the hill for more powder.
    And they truly never “detached” from the wire, as the ‘attachment device” was a ring, slightly larger than the wire, that when “tilted” would prevent the wire from gliding through and hence “attach”.
    Simple system, fast, and reliable.

  • torn edge

    I remember a feature on a ’60’s fixed chair at Timberline. They had a large net attached to the upper bullwheel shack. This was so if you failed to manage to get off at the correct unloading ramp, but were about to get off too late just past the bullwheel and past the shut off wand, you would fall into the net instead of all the way to the snow 40 feet below. I saw people who were caught in the net.

  • Surly Liftie

    One more difference between fixed grips and detaches: Fixed Grip chairs can run in much higher winds than detachables, making them more usable in the higher difficulty terrain mentioned in the article.

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