Elevator Troubleshooting & Repair. David Herres

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СКАЧАТЬ of the hoistway.

      ■ Rated speed: The speed at which an elevator is designed to operate.

      ■ Car or counterweight safety: A mechanical device attached to the car, car frame, or to an auxiliary frame, or to the counterweight or counterweight frame in order to stop and hold the counterweight under one or more of the following conditions: predetermined overspeed, free fall, or if the suspension ropes slacken.

      ■ Traveling cable: A cable made up of electric conductors, which provides electrical connection between an elevator car or counterweight and a fixed outlet in the hoistway or machine room.

      ■ Unintended car movement: Any movement of an elevator car that is not intended car movement, resulting from a component or system failure.

      Besides the foregoing definitions, which give us a valuable overview, Part II (Hoistways and Related Construction for Electric Elevators), Part III (Machinery and Equipment for Electric Elevators) and Part IV (Hydraulic Elevators) provide specific mandates and construction details. It is necessary to comply with these ASME A17 provisions in order to ensure that existing installations remain safe for workers and users. In performing repairs, it is essential that safety mechanisms remain in place, intact and fully functional. Moreover, workers should constantly evaluate the overall installation in the context of NEC and ASME A17 compliance. Additionally, Occupational Safety and Health Administration (OSHA) regulations are relevant to workplace safety. Keep in mind that most elevator accidents involve not members of the public who are using the equipment, but workers who are installing, maintaining, and repairing it. The obvious hazards are falling, being crushed, and being electrocuted. Additionally, there are long-term health hazards. Proper workplace procedures protect technicians and workers.

      ASME A17 Part II applies to hoistways and related construction for electric elevators. It begins with the very basic statement that hoistways are to be enclosed throughout their height. The enclosure protects elevator machinery to a limited but very significant extent from fire that may occur in an adjacent area. This buys time for elevator occupants to descend to the ground floor (Phase I) and for firefighters to take manual control of the elevator (Phase II) so that they can endeavor to halt the fire and perform rescue operations.

      Notwithstanding the fact that the hoistway protects the car and occupants from an external fire, the fact must be recognized that in some instances this vertical shaft can act as a highly efficient flue, increasing a fire’s temperature and facilitating its spread to upper floors. We shall see in Chapter 1, History, some attempts to confront this problem, for example by installing safety hatches, which consisted of sliding or hinged panels at each floor to create a series of closed compartments to control the draft. These panels would open to allow the car to pass. The hoistway moreover serves as a supporting structure for cable sheaves, counterweight guards, doorways at landings, control wiring, guide rails, and safeties.

      Protection is to be provided around elevators adjacent to areas permitting passage of people and adjacent to areas permitting storage. This protection is permitted to be fixed guards, or sufficient distance from the moving portion of the elevator, or a combination of both, so that no one can accidentally come in contact with the elevator. Hoistway enclosures must have substantially flush surfaces on the hoistway sides used for loading and unloading. Landing sills, hoistway doors, door tracks, and hangers are permitted to project inside the hoistway enclosure.

      ■ Where a car leveling device is provided and the hoistway edge of the sill is either flush with or projects into the hoistway, the guard is to have a straight vertical face extending below the sill not less than the leveling zone plus three inches.

      ■ Where the sill projects inward from the hoistway enclosure, the bottom of the guard is to be also beveled at an angle of not less than 60 degrees nor more than 75 degrees from the horizontal or the guard is to be extended from the hoistway edge of the landing sill to the top of the door hanger pocket of the next entrance below.

      ■ Where no car leveling device is provided and the sill projects inward from the general line of the hoistway, the guard is to be either beveled at an angle of not less than 60 degrees nor more than 75 degrees from the horizontal, or it is permitted to have a straight vertical face extending from the hoistway edge of the landing sill to the top of the door hanger pocket of the next entrance below.

      ■ Metal guards are to be installed in the pit and/or machine room located underneath the hoistway on all open sides of the counterweight runway except that where a compensating chain(s) or rope(s) is attached to the counterweight; the guard is permitted to be omitted in the pit on the side facing the elevator car to which these chains or ropes are attached.

      ■ Where pit-mounted buffers are used, the guard is permitted to be omitted where the bottom of the counterweight resting on its compressed buffer is seven feet or more above the pit floor or above the machine or control room floor if located under the hoistway.

      ■ A permanent means of access to elevator machine rooms and machinery spaces is to be provided for authorized persons. Access doors to machine rooms and machinery spaces are to be kept closed and locked. The only means of access to a machine room is not to be through the hoistway. Permanent lighting is to be provided in all machine rooms and machinery spaces.

      ■ Means of access for authorized personnel is to be provided to all pits. A stop switch is to be provided in the pit for every elevator.

      ■ For hoistway doors, interlocks are required for passenger elevators.

      ■ Elevators that are operated from within the car are to have elevator parking devices installed at every landing that is equipped with an unlocking device.

      ASME A17 Part III covers machinery and equipment for electric elevators.

      ■ Car and counterweight buffers or bumpers are to be provided. Solid bumpers may be permitted in lieu of buffers.

      ■ On rod-type counterweights, the rod nuts are to be cotter-pinned and the tie rods are to be protected so that head weight cannot crush the tie rods on buffer engagement. The weights are to be protected so they cannot be dislodged.

      ■ Every elevator car is to have a platform consisting of a non-perforated floor attached to the platform frame supported by the car frame, and extending over the entire area within the car enclosure.

      ■ Hinged platform sills, where provided, are to have electric contacts that will prevent operation of the elevator by a normal operating device unless the hinged sill is within two inches of its fully retracted position.

      ■ The elevator is permitted to be operated by the leveling device in the leveling zone with the sill in any position.

      ■ Floating (movable) platforms that permit operation of the elevator when the car door or gate is not in the closed position are prohibited.

      ■ Cars are to be fully enclosed on all non-entrance sides and on top.

      ■ Cars are to have a car door or gate provided at each entrance equipped with a car door or gate electric contact. It is to be positively opened by a lever or other device attached to and operated by the door or gate.

      ■ For elevators installed in enclosed hoistways, cars are to be provided with a car top emergency exit with a cover hinged or otherwise attached to the car top so that the cover can be opened from the top of the car only, and opens outward. Interiors of cars are to be provided with electric light or lights. No less than two lamps are to be provided.

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