elevators: kinds, functions, mechanisms

8/11/2019 Elevators: Kinds, Functions, Mechanisms

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Elevators

Functions & Mechanisms


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Outline

Definition

Major Elevator Designs

Hydraulic Elevator System

Roped Elevator System

MRL


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Definition

Compartment attached to a rope

Modern Passenger & Freight Elevators are more complex

Mechanical Systems

Control Mechanism

Safety Devices


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Major Elevator Designs

Three Major designs are:

Hydraulic Elevator

Traction (Roped) Elevators

Machine room less


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Hydraulic Elevator System: Operations


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Hydraulic Elevator System: Operations

Car Approached Floor:

Control System (CS) sends signal to Electric Motor (EM) To

gradually shut the pump Pump off: No more fluid to cylinder

The fluid already in the cylinder can not escape as Valve is stillclosed

Piston rests on fluid and stays where it is

To Lower Car: CS sends signal to Valve

Fluid can flow to tank

Weight of car & cargo pushes down on piston: car descends

To stop car at any floor, CS closes the valve


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Hydraulic Elevator System: Pros &Cons

Pros

Easily multiply the relatively weak force of the pump togenerate stronger force needed to lift the car

Cons

Size of Equipment Dig Deeper: 10 story building, dig at least 9 stories deep

Fairly inefficient: Takes lots of energy and do not reserve it, soone have to regenerate energy on every turn


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Rope Elevator System: Operations


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Rope Elevator System: Operations

Traction steel ropes are attached to car and looped around sheave

The other end of rope is connected to a counterweight

Why CW?

To conserve energy: PE levels shift

To act as a see-saw

Sheave is connected to electric motor and it raises/descends the elevator according to

the motion of motor Gearless Elevators: Motor rotates the sheave directly

Geared Elevators: Motor turns a gear train to rotate the sheave

Car and CW rides on guide rails along the sides of elevator shaft. No swaying back andforth


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Rope Elevator System: Gearless


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Rope Elevator System: Geared


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Rope Elevator System: Pros & Cons

Pros

Versatile Efficient

More safety systems

Cons

Machine rooms must be air conditioned Energy cost


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Rope Elevator System: Comparison

Rise Limitations

300 feet (G) Unlimited (GL)

Cost

150,000 200,000 (G)

200,000 + (GL)

Speeds

350-500 fpm (G)

500 1800+ (GL)


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Safety Systems

Hollywood?

Line of Defenses

Rope SystemSeveral length of steel material is used in each ropeMultiple ropes (between 4 & 8)Powerful enough to deal with the weight of car and

counterweight Safeties

Built in braking systems that can grab railIt is activated by a governor if elevator moves too fast


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Safeties: Governor System

Governor rope looped around a governor sheave

Connected to the car and another weighted sheave atthe bottom of the shaft

As car speed up so does the governor


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Safeties: More Backups

Electromagnetic brakes (open position): Engages whencar stops

Automatic breaking system: Stop the car if it moves toofar, located the top and bottom

Shock Absorber System: piston mounted in oil filled

cylinder and acts as a giant cushion

Load sensors


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Making Rounds?

Computer control

Buttons in car and floor

Vertical holes along the shaft (magnetic or light)

Building with many floor

Avoid reversing the elevator direction

Passenger traffic in specific times

Computer directs to the fastest elevator to desired floor

Compass (OTIS Vs. Schindler)


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Automatic Doors


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Machine Room Less


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Thanks!

elevators: kinds, functions, mechanisms

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