21ST CENTURY HIGH-RISE TRAINING SERIES To meet the demand for an ever-more efficient and cost-effective elevator system for high-rise buildings, manufacturers have developed a new concept that can eliminate the need for roof elevator penthouses. Doing so saves building owners an average of...
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21ST CENTURY HIGH-RISE TRAINING SERIES
To meet the demand for an ever-more efficient and cost-effective elevator system for high-rise buildings, manufacturers have developed a new concept that can eliminate the need for roof elevator penthouses. Doing so saves building owners an average of $35,000 by not having to construct this enclosure, or provide heating, ventilating and air conditioning (HVAC), lighting and fire protection. This new concept also eliminates the need for elevator machine rooms, which take up valuable space within the tower when there are multiple elevator banks involved (i.e., low, mid and high banks). All fire departments should be aware of this, since it can affect standard operating procedures (SOPs) for elevator emergency responses.
Although there are several variations of this new concept, this article will focus primarily on the introduction of the "Gen2" elevator system, which is patented and manufactured by Otis Elevator Co. It is indeed the "next generation" of elevators. By seeing beyond the limitations of conventional wire ropes, Otis found a way to increase flexibility and strength with the use of polyurethane-coated galvanized steel belts that provide greater traction and are two-to three times more durable than conventional wire ropes.
The new design also eliminates the problems associated with rust and lubrication requirements of wire ropes. Traditional wire ropes require a large bending radius, which requires a sheave at least 40 times the diameter of the wire rope.
In a conventional traction system, the drive sheave and hoist motor are located in the machine room above the hoistway, along with the governor and a controller. In a conventional traction configuration, a single machine room may contain the controls, governors, hoist motors and associated electrical equipment for several elevators. Structural steel or concrete support is required for each elevator.
In the Gen2 system, the machine, governor and support elements are combined into a compact machine mounting structure housed within the upper region of the hoistway, eliminating the need for a rooftop machine room. The Gen2 coated-steel flat belts allow a significantly smaller bending radius over conventional wire ropes. The sheave height requirements are reduced to only four inches, which means the elevator motor runs at a faster, more efficient speed. The typical sheave height on regular traction elevators is about 36 inches high (see photo on page 118). The smaller sheave requirement allowed Otis to engineer a unit that is 70% smaller and 50% more efficient than conventional geared machines.
The new, permanent-magnet gearless machine's sealed bearings require no oil and eliminate the energy loss of larger systems, reducing power consumption. The unique, lubrication-free system eliminates the repeated lubrication, clean-up and hazardous waste disposal of conventional systems. The Gen2 roller guides are also lubrication-free, unlike conventional hoistway slide guides.
Another advantage of the Gen2's design includes the reduction of car noise by 30% over traditional systems, as well as reducing vertical and horizontal vibration by as much as 75% when compared to conventional equipment. The end result is a much quieter, smoother ride. Harnessing new technologies to fit within existing industry standards, Otis has created a smart, compact system that defines the next generation in efficient elevator operation. It should be noted that, at present, the maximum rise with this system is 300 feet, or around 30 floors in a hotel/residential setting where the floor-to-floor ratios are about 10 feet. It can handle up to eight cars in a group or four cars in a "bank," which is mandated by code.