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Traction elevators are further classified
as Geared and Gearless. Geared Traction elevators
are controlled by either AC or DC power. They use
worm drives to control the movement of the cars by
rolling steel hoist ropes over a drive sheave which
is attached to a gearbox. They have speeds up to 1000
ft/min or 5 m/s. They are normally preferred for Passenger
lifts as they provide fast mobility. The Gearless
Traction elevators generally low speed elevators with
the drive sheave directly attached to the motor. In
both the types, cables are attached to a hitch plate
on top of the cab and looped over the drive sheave
to a counterweight attached to the opposite end of
the cable in effect reducing the pulling power needed
for the elevator. The weight of the elevator is generally
equal to the empty weight of the cab plus 50% of the
capacity of the elevator. In some cases there are
two elevators side by side with one always moving
upward and the other moving downwards. This way they
act as counterweights for each other. This system
is most commonly seen in office complexes.
Hydraulic elevators are normally
installed in mid sized buildings around 3 to 10 floors.
They make use of a hydraulically powered plunger to
push the elevator upwards. Roped hydraulic elevators
use a combination of ropes and hydraulics. Twin post
hydraulic elevators provide higher travel distance
without the need for an underground hole.
LIFTS
The following
kinds of lifts are available for purchase in the market
through a host of different producers.
a)
Passenger Lifts
These are designed specifically for
moving people. Depending on the kind of building and its
size where such elevators serve, their speed and
capacity is decided. In most residential complexes with
medium rise buildings the speed of such elevators is
around 1m/s. The load capacity is typically about 600
kg. However, in large and tall office complexes where a
large number of people have to be moved and quickly the
lifts are as fast as 7m/s and have a capacity of 30 – 40
people.
b) Goods Lifts
These lifts operate
at considerably lower speeds around 0.5m/s. They are
primarily designed to handle goods of all kinds. Thus
they are able to handle heavy loads. Most of these lifts
are around 3-5 m in width and can carry loads up to 5000
kg and more.
c) Hospital/ Stretcher Lifts
These lifts are so designed to provide maximum space
and smooth & comfortable travel. In addition they
also have high precision to the inch so that the
elevator stops accurately at the doors. These lifts too
have a high capacity and can fit nearly in 25 people in
one travel.
d) Dumbwaiters/ Service Lifts
These lifts are designed to accommodate fast
movement of light weight objects. Thus, they are most
commonly used in commercial organizations and hotels to
move mails, food, cutlery etc. The maximum weight
carrying capacity of such elevators is around 250-300
kg.
Most of the elevators mentioned above are
traction controlled but the hydraulic variety can also
be bought.
LIFT MAINTENANCE
a) Lift Cabins
A variety of designs of the lift cabins are
available. So you can choose to have a glass faced
elevator or maybe even a wood faced one.
b) The
Winding Engine
This converts and controls the
electrical energy for the up and down movement of the
elevators. The winding engine consists of Reduction
Gear, Electric Motor, Brake, Bed Plate and Rope
pulley.
c) Main Motors
These are the driving
force behind the elevators and as such need to be highly
safe and dependable.
d) Gate Locks & Floor
Selectors
These are important from the point of view
of safety and reliability.
e) Control Panel with
Micro Processor
Some other additional parts and
features can also be purchased. These include:
f) Remote Locking
g) Temperature and Time
Indicators
h) Overload Warnings
i) Automatic
Lights and Fans
BRANDS
The international
market for elevators is highly competitive. The top
names include:
• OTIS ( The largest elevator
company)
• Schindler Group
• KONE
•
Mitsubishi
• Toshiba
The Indian scene too has a large number of
players on the elevators front. The popular ones
being:
• Johnson Lifts
• Kinetic Elevators
• Monarch Elevators
• Omega Elevators
• East
India Elevators Pvt. Ltd.
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