Figure 3 : A comparison of energy consumption among different elevator systems . ( Source : http :// www . otisworldwide . com ).
will result in the greater generated energy ( Figure 3 ).
Elevator Rope The elevator rope is an essential component of traction elevators because it connects the elevator engine with the cab , sheaves , and counterweight . Conventionally , ropes are made of steel , which is strong enough to hold cabins . However , in supertall and mega-tall buildings , as these ropes get longer , they get extremely heavy — the rope weight increases exponentially with height . In very tall buildings , ropes may stretch for too long , adding dozens of tons of additional weight that can result in the rope breaking or snapping . In very tall buildings , almost 70 % of the elevator ’ s weight is attributed to the cable itself , and when the rope gets too long it cannot support its weight [ 29 ].
The total rope ’ s weight for an elevator with a rated load of 2,000 kg at a travel distance of 500m can be about 27,000kg . This weight needs to be accelerated and decelerated , and starting currents and energy consumption grow fast with the increase in height ([ 29 ], p . 822 ). Further , when a 50 – 70 ton rope moves just 21 passengers , the long-term financial and ecological values of these systems are questionable . Another significant problem with very long cables is that during strong winds , they over sway and vibrate like guitar strings . In response to these problems , elevator companies have been working on improving cable capabilities .
Schindler invented the aramid fibre rope , which is stronger and lighter than the conventional steel rope . Similarly , Otis has designed compact Gen2 lifts that replace the steel rope with a band of ultra-thin cables encapsulated in a polyurethane sheath . According to Otis , the new belt system is stronger and enjoys greater longevity than its original steel cables ( Figure 4 ). Mitsubishi has manufactured a stronger , denser rope that incorporates concentric-layered steel wire . These stronger and lighter ropes require less energy to move and transport elevator cabs , leading to significant power savings .
However , the most significant breakthrough came recently from KONE . The “ UltraRope ” comprises a carbon-fibre core and a unique high-friction coating , making it extremely light , enabling cars to travel up to 1,000m ( 3,280 ft ). This is double the current maximum distance of 500m ( 1,640 ft ) that cars can travel . Further , in the case of maintenance and repair , the lighter UltraRope would require much less time for replacement than regular ropes , reducing downtime considerably . This large decrease in
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