Elevators and Escalators

Traction Lift

In a typical elevator, the car is raised and lowered by three to eight motor-driven wire ropes that are attached to the top of the car at one end, travel around a pair of sheaves, and are again attached to a counterweight at the other end. The counterweight adds accelerating force when the elevator car is ascending and provides a retarding effort when the car is descending so that less motor horsepower is required. The counterweight is a collection of metal weights that is equal to the weight of the car & containing about 50% of its rated load. A set of chains are looped from the bottom of the counterweight to the underside of the car to help maintain balance by offsetting the weight of the suspension ropes. Guide rails that run the length of the shaft keep the car and counterweight from swaying or twisting during their travel. Rollers are sometimes attached to the car and the counterweight to provide smooth travel along the guide rails.

Most elevators earlier used a direct current motor because it’s speed can be precisely controlled to allow smooth acceleration and deceleration. Now a days AC Motors are frequently used and speed is typically varied using sophisticated ACVVVF Drives, which results in accurate floor leveling of even fully loaded elevator. However in goods elevator choice of fitting ACVVVF Drive depends on cost benefit approach taken by client. The elevator controls vary the motor’s speed based on a set of feedback signals that indicate the car’s position in the shaftway. As the car approaches its destination, a sensor near the landing, signals the controls to stop the car at floor level. Additional shaftway limit sensors are installed to monitor over travel & under travel.

Hydraulic Lift
Hydraulic elevators are limited to no more than six or seven story service. The simplest hydraulic elevator uses a single stage hydraulic cylinder under the cab. An electric motor powers the cab. The pump forces fluid in the cylinder below the piston, forcing the piston to rise. When the elevator is descending its P.E. is converted to heat that must be dissipated. In these systems the hydraulic cylinder is housed in a well bored in the ground. The well has a impermeable liner to prevent hydraulic fluid from leaking in to the ground and contaminating ground water. The hole is essentially deep as the lift height. In addition since the fluid reservoir and pump apparatus are preferentially located at the lowest level of the building, no machine room is required.

Traction Vs. Hydraulic Lift
Two types of elevators, which are hydraulic and traction, have been widely used as vertical transportation equipment. Hydraulic elevator has lower ownership costs and can be quickly installed if compared to traction elevator. Yet the hydraulic elevator is noisy, slow with poorer ride quality, and it uses a lot of energy and has the potential for environmental damage from leaking hydraulic fluid. On the other hand, the traction type is faster and smoother but it costs little more to buy and own. In addition, both types of elevators can slow building completions with their special construction requirements, if not planned well in advance i.e. at the time, building drawings are being prepared.

Elevator Safety
Elevators are inherently safe. Their safety record, that of moving millions of passengers every day, without incident, is unsurpassed by any other vehicle system. The only way to get top performance and long life from equipment is preventive maintenance, which means regular inspection, adjustment and lubrication for elevators and escalators. These cares keep elevators and escalators operating at their best.
At Beacon, safety is of paramount importance and utmost care is taken to test/check all the critical components, sensors, controls & devices so as to derive maximum operational efficiency without failure. In order to make our elevator safe to ride we take care that all the mandatory and additional safety features are provided in all types of lift. Our team of dedicated engineers constantly analyze the breakdown pattern and pass it to the R& D team, which in turn use this information to further enhance & improve the riding quality, making beacon elevators smoothest & safest.

This entry was posted on Tuesday, October 9th, 2007 at 10:16 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.