Blog

Know Your Elevator
Series 2

Door &
Doors Operator

Synopsis

We shared with you earlier the root causes of fears that get instilled in people’s minds. Like any other piece of equipment or a machine, one becomes confident when she or he knows at least the basic operation of the same. Eg, One may know how to drive a car on a straight road but on slopes of gradient how you and what gears are to be used may not be known. I have seen many novice drivers (especially if the car is new) who may not know where the lever of the boot or petrol tank is located.

Back to the elevator, let me ask you what are the parts that a user can see being used and are moving the most. There are the doors and door operators and the main car in which passengers travel. Let us first familiarize ourselves with the doors, door operator, and car.

Doors & Door operator

There are two types of doors in any elevator. One is for the passenger car and the other is at the landing or a floor. If a building has 6 floors, then the elevator in that building will have 6+1 doors (7 doors) The door for the car is known as a car door and door and the floor is known as a landing door

The manual door elevators do not have a door operator. As the name suggests. The doors of such elevators are operated by the elevator users or passengers. Most of the time they are collapsible gates or manual sliding doors in the car and collapsible gates and wooden or steel swing doors at the landings.

Elevators installed in the 20th century were predominantly manual door elevators till around 8 stops and above that were automatic doors. Why? Because that was a recommended norm of the National Building Code (NBC) and a mandatory rule by the lift inspector of the state. In those days only 8 states had a lift or an elevator inspector who was a certifying authority and without his certificate the use of the elevator was illegal. It is similar to a car that cannot be driven unless it has a registered number.

Today 12 state Governments in India have an electrical Inspectorate department to inspect and certify every installed elevator.

Please be aware that doors of any proper and certified elevator are designed and installed in such a way that the car cannot move when the landing door is open; which means when the elevator car say is on 5th Landing, only the 5th-floor landing door can open, while landing doors on all other floors are interlocked; be it manual door or automatic door. While the construction of manual door elevators is very simple, let us see how an automatic car door is constructed. The most common models (plan view) are shown in Figure 1. Here we can see one panel sliding doors, two-panel centre opening doors, and two-panel side opening doors (also popularly known as telescopic doors) They are made of fast-moving and slow-moving panels retracting on the same side. Opposite 4-panel (that is the combination of 2-speed doors and so one

While we get the clarity of the automatic door systems, the parameters that decide which door system to use are decided based on the architectural requirement and the clear door width required

What moves these automatic doors? It is the door operator

The door operator is an electromechanical device that by means of a mechanism, transforms the rotational movement of an electric motor into horizontal movement of panels. The most simple door operator contains a sensitive device to limit the force and energy produced by the panel movement.

A decade ago elevator manufacturers used edge-of-shoe technology, which meant the edge would softly touch the passenger moving out of the cat and retract back. Now the complete door opening system is a multi ray one where the passenger body just cuts the rays and the door retracts. Electronics plays an important role in a door operator making it smoother and power saving (they use the VVVF technology) In fact the complete safe operation of the door is assured and the door operator due to the self-learning system controls the panel opening and closing system, the slowing phases and based on the panel weight detects through measurement of drive currents the reversal of the car door in case of obstacle in the path. Eg if a stone is stuck in the door sill, the door will keep on retracting back till the stone is removed. This takes us to the subject of housekeeping of the elevators. It is important that the elevators just do not need technical maintenance, they need proper housekeeping. An abused or badly maintained elevator will behave erratically.

Normally, housekeeping is done by the elevator service provider whom you need to have a comprehensive annual maintenance contract (AMC). If the elevator use is rough and there is a tendency to abuse, this must be specified while signing the annual maintenance contract. This will ensure that the frequency of visits housekeeping team will be specified in the AMC.

The other moving component in an elevator is the car. Like an automobile car which considered good, if it has a good ride quality. The same applies to an elevator. Here the good part is the ride quality is not road dependent as the car (rather the car frames move on the rails). The components that impact the elevator ride quality are the guide shoes (or roller guides in case of higher speeds above 2.5 mps) and the installation of rails.

We will cover the other safety related components and other elevator parts in the later weeks

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