Elevator Troubleshooting & Repair. David Herres

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СКАЧАТЬ is to be provided with a safety capable of stopping and sustaining the car with rated load. When the safety is operated by a governor, the safety is to be capable of stopping and sustaining the car with rated load from governor tripping speed. Counterweight safeties are to be provided and are to be capable of stopping and sustaining the counterweight.

      ■ Safeties are to be applied mechanically. Electrical, hydraulic, or pneumatic devices are not to be used to apply the safeties nor to hold the safeties in the retracted position. Safeties that depend upon traction for application are prohibited. When car safeties are applied, no decrease in tension in the governor rope nor motion of the car in the down direction is permitted to release the safeties, but the safeties are permitted to be released by the motion of the car in the up direction.

      ■ Rail lubricants or coatings that will reduce the holding power of the safety or prevent its functioning as required are not to be used.

      ■ The car and counterweight guide rails are to extend at the top and bottom to prevent the guiding member from disengaging from the guide rails in the event that either the car or counterweight reaches its extreme limit of travel.

      ■ Sheaves and drums are to be of cast iron or steel and are to have finished grooves for ropes.

      ■ Winding drum machines are to be provided with a slack rope device having an enclosed switch of the manually reset type that will cause the electric power to be removed from the elevator driving-machine motor and brake if the hoisting ropes become slack or broken.

      ■ In indirect-drive machines, each chain or belt in a set is to be continuously monitored by a broken belt or chain device of the manually reset type, which will function to automatically interrupt power to the machine and apply the brake in the event any belt or chain in the set breaks or becomes excessively slack. If one belt or chain of a set is worn, stretched, or damaged so as to require replacement, the entire set is to be replaced. Sprockets and toothed sheaves are also to be inspected on such occasions and to be replaced if noticeably worn.

      ■ The elevator-driving machine is to be equipped with a friction brake applied by a spring or springs, or by gravity, and is to be released electrically. The brake is to be designed to have a capacity sufficient to hold the car at rest with its rated load.

      ■ Enclosed upper and lower normal stopping devices are to be provided and arranged to slow down and stop the car automatically, at or near the top and bottom terminal landings. These devices are to function independently of the operation of the normal stopping means and of the final terminal stopping device.

      ■ Manually operated rope (shipper rope) or rod-operating devices, or rope-operating devices actuated by wheels, levers, or cranks are not to be used.

      ■ Handles of lever-type operating devices of car-switch operation elevators are to be so arranged that they will return to the stop position and latch there automatically when the hand of the operator is removed.

      ■ Elevators with automatic or continuous-pressure operations are to have a continuous pressure button operating switch mounted on the top of the car for the purpose of operating the car solely from the top of the car. The device is to operate the car at a speed not exceeding 150 feet per minute.

      ■ The means for transferring the control of the elevator to the top-of-car operating device is to be on the car top and located between the car crosshead and the side of the car nearest the hoistway entrance normally used for access to the car top.

      Electrical Protective Devices, as covered in ASME A17, Part III, will be discussed in detail in Chapter 5, Troubleshooting Elevator Systems.

      Hydraulic elevators, as covered in ASME A17, Part IV, will be discussed in detail in Chapter 2, Types of Elevators.

      The requirements listed above are a small part of the entire elevator Code. They are presented by way of introduction to the general topics covered in this book.

ACKNOWLEDGMENTS

      Many thanks to:

      ■ Judy Bass, Publisher, Industrial Press Inc., who envisioned this work and suggested viable approaches

      ■ Janice Gold, copy editor, and Patricia Wallenburg, compositor, who together wrote the book on competency and accuracy

      ■ Judi Howcroft, supreme nature and industrial photographer, who showed me the way, departed, and lives on among the stars

      ■ Deidre Schardine, an ongoing inspiration, who knows what is right and how to get there

      Elevator Troubleshooting

       & Repair

CHAPTER 1

       HISTORY

      It is likely that animal- and human-powered elevators predated written history. Unlike masonry and stone buildings, the cars were probably woven baskets or wooden platforms with or without guardrails, and the support structures built of wooden logs, so these remains would have decayed centuries ago. We can only surmise that they existed, powered by domesticated animals on the ground, who worked long hours at a turnstile. Alternatively, occupants of the car may have pulled a looped rope that turned a pulley with more ropes that lifted the car, as shown in Figure 1-1.

FIGURE 1-1 The rope was operated from within the car. The hoistway was primitive, but it did the job.

Early Elevators

      Vitruvius (c. 80–15 BC), a Roman author, architect, and engineer, provided the first extant written reference. He reported that the Greek mathematician Archimedes (c. 287–212 BC) built a bank of elevators operated by hoisting ropes wrapped about a drum. It was turned by humans and this torque was applied to a capstan, causing platforms to lift gladiators and fierce animals through vertical shafts into the arena. In the seventeenth century, English and French monarchs built “flying chairs” to discreetly transport their mistresses to upper palace levels. These machines, powered by humans and animals, were eventually eclipsed by steam, water, and finally electric motors.

      Where it gets interesting, from our point of view, is in the nineteenth century. During this 100-year period, the elevator evolved from steam-powered platforms used to move coal in English mines, to electrically-powered elevators that lifted passengers to ever greater heights in comfortable rooms with plush furniture.

      In the late 1790s, William Strutt (1756–1830), shown in Figure 1-2, assumed control of his father’s textile mills in England. Among many projects, including fireproofing and improving the heat system, he designed a combination passenger and freight elevator, known then as the crane. It was adjacent to the main stairway and was used to transport workers within the five-story building. Strutt’s elevator was powered by a flat belt, running off of power shafting that ran throughout the building, presumably СКАЧАТЬ