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Past, Present, and Future: Elevators
Depending on your definition of the word, the dawn of the elevator was as early as the 1820s. From the middle of the 19th century, power elevators (steam- or water-driven) conveyed materials in factories and warehouses. Many elevators were also driven using leather belts and pulley systems that operated the elevator and much of the building's machinery. Elevator equipment moved up and down through floor cavities (or “trap doors”) that opened and closed as needed. “There were no enclosures - no car enclosures, no hoistway enclosures,” explains Edward Donoghue, administrator, National Elevator Industry Inc. (NEII), Salem, NY. “Over the years, these conditions were found to be safety hazards. The American Society of Mechanical Engineers got together with the insurance, enforcement, and elevator industries and developed what became the ASME A17.1 Safety Code for Elevators and Escalators, the first edition being in 1921. That edition was a pamphlet with about 25 pages; today’s edition is a large book close to 450 pages.”
Due mostly to changes in code, the industry moved to enclosed cars and hoistways, and to traction and hydraulic elevators. And, wherever there was an elevator, there was an elevator operator. A big advancement occurred shortly after World War II, when basic automation was incorporated into elevator equipment: Improvements in electronics made it possible for passengers to use push-buttons to operate elevators that once required an attendant.
In more recent years, elevator relay control systems have gone to solid state. “We used to drive high-speed elevators with DC; we converted the building’s AC to DC using motor-generator sets. Today, it’s all done with solid-state devices,” says Donoghue.
Other changes on the horizon: machine-room-less elevators and destination-oriented elevators (also called “destination-based” elevators).
Machine-room-less elevators incorporate machinery and equipment into the hoistway or closets, eliminating the need for a separate machine room. “The machine-room-less elevator is becoming very common. The latest supplement to the ASME A17.1 is recognizing them,” Donoghue points out.
Destination-oriented elevators eliminate control buttons in elevator cars; instead, passengers enter the elevator-lobby area and select a floor. Based upon the floor they’re visiting, they’re assigned an elevator car. “It’s a faster way of moving people,” says Donoghue.
Another change in the industry looms with regards to codes. “Our codes haven’t kept up with new technology. There is major work going on in the code-writing arena, which - in the near future - will hopefully allow us to keep up with technology as it comes forward and still have safe elevator equipment that complies with codes,” Donoghue explains. “The ASME A17.1 Committee is in the final throes of developing what’s known as a Performance-Based Safety Code for Elevators and Escalators.”
Instead of stating specific requirements (like the A17.1 does), the performance-based code will require compliance with Global Essential Safety Requirements (GESRs). While the A17.1 might state that manufacturers must provide a non-perforated car enclosure with 7-foot walls, a ceiling, and with no through openings in the walls, a performance-based code would indicate that protection against falling and entanglement with equipment adjacent to the elevator car must be provided. The manufacturer then chooses how it will meet that code. It performs a risk analysis to show how compliance with the GESR will be provided by the new design, and takes that risk analysis (along with the design) to an accredited elevator/escalator certifying organization (AECO). The AECO performs an analysis to ensure that the manufacturer has done the proper risk analysis, mitigated the hazards, and put into place all of the necessary design and criteria to assure that the GESRs (stated in the performance-based code) were met. If they are, the manufacturer receives a certificate from the AECO, which is presented to the authority having jurisdiction, showing proof of compliance with the code.
“Once that comes on the street and starts to be accepted by the enforcement authority, you’ll see more and more new technology,” notes Donoghue.
Leah B. Garris (firstname.lastname@example.org) is associate editor at Buildings magazine.