Elevator
Raw Materials An elevator is a platform, either open or enclosed, used for lifting people or freight to upper floors within a building. Raw Materials The elevator car itself is constructed with a steel framework for durability and strength. A set of steel beams above the car, called the crosshead, span the elevator shaft from side to side and hold the pulley for the hoist cable. A steel structure, called the sling, extends down the sides of the car from the crosshead and cradles the floor, or platform. The sides of a passenger elevator car are usually made from steel sheet and are trimmed on the inside with decorative paneling. The floor of the car may be tiled or carpeted. Handrails and other interior trim may be made from stainless steel for appearance and wearability. A suspended ceiling is usually hung below the actual top of the car and may contain fluorescent lighting above plastic diffuser panels. The elevator controls, alarm buttons, and emergency telephone are contained behind panels in the front of the car, next to the doors. Steel guide rollers or guide shoes are attached to the top and bottom of the sling structure on each side to run along the guide rails. The guide rails are also steel and are attached to the interior walls of the elevator shaft which runs from the top of the building to the bottom. The emergency brake mechanism consists of two clamping faces which can be driven together by a wedge to squeeze on the guide rail. The wedge is activated by a screw turned by a drum attached to the emergency cable. The Manufacturing Process 1. The elevator cars are built at the elevator manufacturer's plant using standard metal cutting, welding, and forming techniques. If the cars will be exposed to the weather during building construction, the interior trim may be installed after the building is finished. 2. The rest of the elevator is assembled on the building site. The building design integrates the elevator shaft from the beginning, and the shaft grows as the building is erected. The walls of the shaft are poured concrete, and the shaft straightness and Most elevators use counterweights which equal the weight of the elevator plus 40% of its maximum rated load. This counterweight reduces the weight the motor must lift and ensures that the elevator cannot fall out of control while the cable is intact. Most elevators use counterweights which equal the weight of the elevator plus 40% of its maximum rated load. This counterweight reduces the weight the motor must lift and ensures that the elevator cannot fall out of control while the cable is intact. other dimensions are carefully monitored as each floor goes up. 3. Guide rails, switch ramps, service ladders, and similar support equipment are bolted into the shaft after the shaft walls are complete, but before the shaft is roofed. 4. While the shaft is still open at the top, a crane raises the counterweight to the top of the building and lowers it into the shaft along its rails. 5. The crane then lifts the elevator car and inserts it partly into the shaft. The guide wheels connect the car to the guide rails, and the car is carefully lowered to the bottom of the shaft. 6. The shaft is then roofed over, leaving a machine room above the shaft. The hoist motor, governor, controller, and other equipment are mounted in this room, with the motor located directly over the elevator car pulley. 7. The elevator and governor cables are strung and attached, the electrical connections completed, and the controller programmed. Traction elevators and escalators These are the most common types of equipment. Cars are maneuvered by means of rolling ropes over a pulley system, and the load is balanced by a counterweight. Accurate control of a high-efficiency motor using an AC drive provides the required ride comfort. Elevator-specific functionalities make it easy to integrate the AC drive into a new elevator series or to modernize existing installations. In escalators, AC drives enable low-speed idling and full-speed operation with soft acceleration and deceleration. The high efficiency and smooth operation of the equipment guarantees its long lifetime. Both new equipment and existing installations benefit from a lower total cost of ownership. Hydraulic elevators Hydraulic elevators, also widely used, have pistons that move the car along guide rails. When AC drives are used, the hydraulic pump is driven in relation to the true demand with the lowest losses. The hydraulic oil doesn’t get hot and the lift will have unlimited cycles per day, shorter cycle times and very high efficiency. Energy savings exceed 50%, and total savings of up to 75% are possible when oil coolers are removed and the air conditioning has less work to do. Modernization of an existing lift to use AC drives can be done in a matter of hours. Ropeways Smooth access to locations at high altitude, in deep snow or that offer spectacular scenery is possible with ropeways. __________ provides the required redundancy by controlling multiple motors or multi-segment motors. The flexibility in application design allows various different configurations for both new and modernization systems. Energy efficiency can be maximized with regenerative drives that feed the braking energy back to the electrical grid. Construction hoists and manufacturing plant elevators Moving people and goods at construction sites is handled efficiently by using rack- and pinion-type hoists and elevators. Multiple parallel motors and a single __________ with dynamic braking enable different capacity hoisting equipment within the same mast or rack. Drives can be installed either inside or on top the car. The drives also offer interfacing to elevator controls and enable accurate landings to floors to increase safety. |