A chairlift (technically, an elevated passenger ropeway), is a type of aerial lift, which consists of a continuously circulating steel cable loop strung between two end terminals and usually over intermediate towers, carrying a series of chairs. They are the primary onhill transport at most ski areas (in such cases referred to as 'skilifts'), but are also found at amusement parks, various tourist attractions, and increasingly, in urban transport.
Depending on carrier size and loading efficiency, a passenger ropeway can move up 4000 people per hour, and the fastest lifts achieve operating speeds of up to 12 meters/second (27 mph, 43 km/h). The two-person double chair, which for many years was the workhorse of the ski industry, can move roughly 1200 people per hour at rope speeds of up to 2.5 m/s. The four person detachable chairlift ("high-speed quad") can transport 2400 people per hour with an average rope speed of 5 m/s. Some bi and tri cable elevated-ropeways and reversible tramways achieve much greater operating speeds. Fixed-grip lifts are usually shorter than detachable-grip lifts due to rope load; the maximum vertical rise for a fixed grip chairlift is 300-400 meters and a length of about 1200 m, while detachable quads and "six-packs" can service a vertical rise of over 600 m and a line length of 2000 m.
A chairlift consists of numerous components to provide safe efficient transport.
The capacity of a lift is constrained by the motive power (prime mover) versus the rope speed, the carrier spacing, the vertical displacement and the number of carriers on the rope (a function of the rope length). Human passengers can load only so fast before loading efficiency decreases; usually an interval of at least five seconds is needed.
Various techniques are used for constructing the rope. Dozens of wires are wound into a strand. Several strands are wound around a textile core, their twist is oriented in the same or opposite direction as the individual wires; this is referred to as Lang lay and regular lay respectively.
Rope is constructed in a linear fashion, and must be spliced together before carriers are affixed. Splicing involves unwinding long sections of either end of the rope, and then winding each strand from opposing ends around the core. Sections of rope must be removed, as the strands overlap during the splicing process.
Every lift involves at least two terminals and—usually—intermediate supporting towers. A bullwheel in each terminal redirects the rope, while sheaves (pulley assemblies) on the towers support the rope well above the ground. The number of towers is engineered based on the length and strength of the rope, worst case environmental conditions, and the type of terrain traversed. The bullwheel with the prime mover is called the drive bullwheel; the other is the return bullwheel. Chairlifts are usually electrically powered, often with diesel or gasoline engine backup, and sometimes a hand crank tertiary backup. Drive terminals can be located either at the top or the bottom of an installation; though the top-drive configuration is more efficient, practicalities of electric service might dictate bottom-drive.
Either diesel engines or electric motors can function as prime movers. The power can range from under ten horsepower (7.5 kW) for the smallest of lifts, to several hundred for a long, fast detachable eight-seat up a steep slope. AC electric motors were the most common, though direct current motors are now economically competitive.
The driveshaft turns at high RPM, but with low torque. The gearbox transforms high RPM/low torque rotation into low RPM/high torque to drive the bullwheel. Higher power is able to pull heavier loads, or sustain a higher rope speed.
Also called a retention bar or safety bar, these may help hold passengers in the chair in the same way as an automotive seatbelt or safety bar in an amusement park ride. If equipped, each chair has a retractable bar, sometimes with attached foot rests. In most configurations, a passenger may reach up and behind their head, grab the bar or a handle, and pull the restraint forward and down. Once the bar has rotated sufficiently, gravity assists positioning the bar to its down limit. Before disembarking, the bar must be rotated up, out of the way.
The physics of a passenger sitting properly in a chairlift do not require use of a restraining bar. If the chairlift stops suddenly (as from use of the system emergency brake), the carrier's arm connecting to the grip pivots smoothly forward—driven by the chair's inertia—and maintains friction (and seating angle) between the seat and passenger. The restraining bar is useful for children—who do not fit comfortably into adult sized chairs—as well as apprehensive passengers, and for those who are disinclined or unable to sit still. In addition, restraining bars with footrests reduce muscle fatigue from supporting the weight of a snowboard or skis, especially during long lift rides. The restraining bar is also useful in very strong wind and when the chair is coated by ice.
Restraining bars (almost always with foot rests) on chairlifts are more common in Europe and also naturally used by passengers of all ages. Some newer chairlifts have restraining bars that open and close automatically.
Many—if not most—installations have numerous safety sensors which detect rare but potentially hazardous situations, such as the rope coming out of an individual sheave.
Detachable chairlift control systems measure carrier grip tension during each detach and attach cycle, verify proper carrier spacing and verify correct movement of the detached carriers through the terminals.
Some installations use brittle bars to detect several hazardous situations. Brittle bars alongside the sheaves detect the rope coming out of the track. They may also be placed to detect counterweight or hydraulic ram movement beyond safe parameters (sometimes called a brittle fork in this usage) and to detect detached carriers leaving the terminal's track. If a brittle bar breaks, it interrupts a circuit which causes the system controller to immediately stop the system.
In May 2006, a cable escaped the sheaves on the Arthurs Seat, Victoria chairlift in Australia causing four chairs to crash into one another. No one was injured, though 13 passengers were stranded for four hours. The operator blamed mandated changes in the height of some towers to improve clearance over a road.
If a passenger fails to unload, their legs will contact a lightweight bar or thin line which stops the lift. The lift operator will then help them disembark, reset the safety gate, and initiate the lift restart procedure. While possibly annoying to other passengers on the chairlift, it is preferable to strike the safety gate (that is, it should not be avoided) and stop the lift than be an unexpected downhill passenger. The majority of chairlifts are rated for zero downhill capacity, so the operator would eventually stop the lift and call for a time-consuming evacuation of the passenger.
The first recorded mechanical ropeway was by Venetian Fausto Veranzio who designed a bicable passenger ropeway in 1616. The industry generally considers Dutchman Wybe Adam to have built the first operational system in 1644. Alpine regions of Europe developed the technology; progress rapidly advanced and expanded with the advent of wire rope and, especially, electric drive. World War I motivated extensive use of military tramways for warfare between Italy and Austria.
The first known chairlift was created for the ski resort in Sun Valley, Idaho in 1936. It was installed on Proctor Mountain, two miles (3 km) east of the more famous Bald Mountain, the primary ski mountain of Sun Valley resort since 1939. The chairlift was developed by James Curran of Union Pacific's engineering department in Omaha during the summer of 1936. Prior to working for Union Pacific, Curran worked for Paxton and Vierling Steel (www.pvsteel.com), also in Omaha, which engineered banana conveyor systems to load cargo ships in the tropics. (PVS manufactured these chairs in their Omaha, NE facility.) Curran reengineered the banana hooks with chairs and created a machine with greater capacity than the up-ski toboggan (cable car) and better comfort than the J-bar, the two most common skier transports at the time—apart from mountain climbing. His basic design is still used for chairlifts today. The patent for the original ski lift was issued to Mr. Curran along with Gordon H. Bannerman and Glen H. Trout (Chief Engineer of the Union Pacific RR) in March 1939. The patent was titled "Aerial Ski Tramway,' . W. Averell Harriman, Sun Valley's creator and former governor of New York State, financed the project. The original 1936 chair lift was later moved to Boyne Mountain, Michigan (U.S.A.) where parts of it are still in use.
FIVE SKI KIDS HURT IN CHAIRLIFT COLLAPSE; TERROR AT THE LECHT SKIERS FALL 20FT TO GROUND AFTER CABLE PYLON ACCIDENT Terror on the Chairlift Five Kids and One Adult Hurt, 30 Stranded at Busy Centre Victims Airlifted to Hospital with Spine and Leg Injuries SKIERS FALL 20FT TO GROUND AFTER CABLE PYLON ACCIDENT Terror on the Chairlift Five Kids and One Adult Hurt, 30 Stranded at Busy Centre
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