Elevator modernization

Elevator modernization (or lift modernization) is the process of upgrading the critical parts of the elevator in order for it to be able to handle new technology, have better performance, improve safety, and even give the aesthetics an up-to-date appeal.

Sometimes, elevator (lift) replacement work also applied in this term.

Introduction

Most elevators are built to provide about 30 to 40 years of service (although some elevators as old as 50 years or more are still in service), as long as service intervals specified and periodic maintenance/inspections by the elevator manufacturer are followed. As the elevator ages and equipment become increasingly difficult to find or replace, along with code changes and deteriorating ride performance, a complete overhaul of the elevator may be suggested to the building owners.

Typically, a modernization will affect the controller equipment (the part of the elevator that controls the movement of the elevator through the floors), the hoist machines and motors (the part of the elevator that does the heavy lifting), electrical wiring and buttons of the cab (controlling the lights, destination floors, etc.,) even the tracks of the doors are sometimes modified and changed, all to keep the elevator up-to-date, and to the aesthetics conscious, paneling, electronics, and additional style changes can also be done in the interior of the cabs.

The process

For starters, an elevator modernization plan will have to be created. This is done usually with the help of an elevator service company which can also do modernization.

This process will determine which parts of the elevator will have to be modernized, the scope of the procedure, and most importantly,  making sure that code compliance is met. Once this is done, preventive maintenance will have to be done until the elevator is removed from service.

During this time, the elevator will be out of service, so building owners will have to compensate for this. This includes proper diversion of building’s traffic, creating contingency plans, and so on. This is needed because depending on the amount of modernization done, the number of elevators, and the size of the building, the whole process may take anywhere from a few months, to a whole year.

When the process complete, elevator service company must complete the elevator examination for newly installed elevator or elevator recently complete the major alterations before it back in service.

Benefits of elevator modernization

Modernization can greatly improve operational reliability by replacing mechanical relays and contacts with solid-state electronics.Ride quality can be improved by replacing motor-generator-based drive designs with Variable-Voltage,Variable Frequency(VVVF) drives,providing near seamless acceleration and deceleration. Passenger safety is also improved by updating systems and equipment(such as double brake system,unintended car movement protection device on the brake systems..etc.) to confirm to current codes.

Problems of elevator modernization

Many vintage elevators enthusiasts dislike elevator modernization,because it reduces the aesthetic appeal of the elevator with a generic,modern design, and also may not blend with the architecture of historic buildings.Also,some people criticize that modernization elevators are not as well made or have as long a lifespan,because of the sensitive electronic controllers,cheaper made mechanical parts,and fast work method.As a result,some people say that elevators should not be modernized,unless it’s absolutely needed.And if so,should be done in a high quality,efficient manner.

What is the traction machine

People usually take elevators everyday.While do you know what is elevator traction machine? If not,the following details will show you.

The elevator hoisting machine generally consists of motor, brake, gearbox and machine base and so on. If you drag a power plant, without intermediate gearbox directly to the hoisting machine and the traction sheave are called gearless machine. Motor armature gearless machine with the brake drum and sheave is directly connected. The power actuator is transmitted to the traction sheave of the hoisting machine via an intermediate gear box called Geared Traction Machine.

Elevator AC motor

1.Characteristics requirements of the motor

(1)A large starting torque;

(2)Starting current is smaller;

(3)The motor should be flat torque characteristics

(4)In order to ensure the stability of the elevator, at rated voltage, the motor slip at high speed should be no greater than 12% at low speed when it is not more than 20%.

(5)It requires low noise, small torque ripple

2. The type commonly used on elevator motor

Single-speed motor

Two-speed motor

Three-speed motor

3.Motor capacity estimates
　　

Worm gear drive

Current speed is not greater than 2.5 m / s, geared traction machine they use a worm gear box, its main advantages are:
   Smooth transmission, low noise operation

   Compact structure, small size
　 Less transmission parts
   With good loading characteristics
　　

1.Worm shaft support mode
Pair Worm located above the worm is called top-mounted, located below the worm called under-mounted.

The advantage of top-mounted is that the housing relatively easy to seal, easy to check, and the the inadequacies is relatively poor lubrication.
　
2.Common worm gear tooth
There are two kinds of common cylindrical and circular arc.

3.Choose worm material
In choosing the material to fully take into account the characteristics of the worm gear, the worm to select high hardness, rigidity good material, the worm should choose wear and good anti-friction properties of materials.　　

4. Requirements of worm meshing characteristics
5. Worm Drive efficiency calculation
6. Worm force calculation
7.Heat balance

Since the worm transmission power of a larger friction loss, the loss of power of the majority is converted into heat, so that the oil temperature rise. High oil temperature will greatly reduce the viscosity of lubricating oil, oil film between the tooth surface damage, resulting in direct contact with the working surface to produce tooth surface gluing phenomenon. To avoid overheating lubricants, designed worm gear box should meet, the heat from the heat emitted worm gear box is greater than or at least equal to the power loss.
　　

Helical gear transmission

In the design of helical gear used in custom elevator should consider the following factors in：
　Cross resilience
　Impact bending stress
　Pitting and wear
　Vibration and noise

Brakes

Brake type:

Elevator brake system should have an electromechanical brake, when the main circuit or control circuit power off, the brake must be action. Cut off the brake current, at least two independent electrical devices should be implemented.
To achieve the braking effect of the brake should be oriented compression spring or the hammer. The braking torque at rated speed should be enough to run and stop the car carrying 125% rated load

The most commonly used elevator brake is an electromagnetic brake.

Dumbwaiter,a small freight elevator

Dumbwaiters are small elevators intended to carry objects rather than people. Dumbwaiters are found within modern structures, including both commercial, public and private buildings, are often connected between multiple floors. When they are installed in restaurants, schools, hospitals, libraries, retirement homes or in private homes, the dumbwaiter generally terminate in a kitchen.

History

A mechanical dumbwaiter was invented by George W.Cannon, a New York inventor.

Cannon first filed for the patent of a brake system(US Patent no.260776) that could be used for a dumbwaiter on January 6^th ,1883.Cannon later filed for the patent on the mechanical dumbwaiter(US Patent no. 361268) on February 17^th, 1887.Cannon reportedly generated a vast amount of royalties from the dumbwaiter patents until his death in 1897.

One of the first non-mechanical dumbwaiters in the world was used bu Thomas Jefferson in his mountain home at Monticello,Virginia.He use it to limit the number of servants around the table to one,so that his guests could enjoy more of the view.

Description

A simple dumbwaiter is a movable frame in a shaft,dropped by a rope on a pulley,guided by rails.Most dumbwaiters have a shaft, cart and capacity smaller than those of passenger elevators,usually 50-450 kgs (100-1000lbs).Before electric motors were added in the 1920s,dumbwaiters were controlled manually by ropes on pulleys.

Early 20th-century codes sometimes required fireproof dumbwaiter walls and self-closing fireproof doors and mention features such as buttons to control movement between floors and locks on doors preventing them from opening unless the cars is stopped at that floor.Most dumbwaiter has external fixtures which contains floor destination buttons,floor position indicator,and built-in inter-phone or normal inter-phone.When a person is using the dumbwaiter,he/she opens the doors manually,load the goods,and closed the doors again before operating the dumbwaiter.After that,he/she pushed the floor buttons to send the dumbwaiter to the desired floor.Sometimes,the person may also using the inter-phone or telephone to contact other person on the other floors.

Type of dumbwaiter

Dumbwaiters typically have two types of landing:Floor type and window type.

Floor type

Floor type dumbwaiter is installed on the same horizontal level with the floor of the passage way to facilitate carriage of goods normally carried on the handcarts.This type of dumbwaiter is normally found in hotels,libraries,or corridor areas.Normally used to carry large goods such as tables.

Window type

Window type dumbwaiter is installed at the height of a man’s waist,so that users can use the dumbwaiter conveniently.This type is commonly found in libraries,offices,hospitals,restaurants,kitchens and other places.It is normally used to carry books,documents,medicines,kitchen utensils,food and beverages and other goods.

Large type

This type of dumbwaiter has a large cab with an external manual gate and it is similar to a normal freight elevator.But there are no buttons inside the car.Some large dumbwaiters may have interior light.Passengers are usually not allowed to enter or ride it for safety reason.Button panel is located on the outside,often has a digital floor indicator.

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Freight elevator types

A freight elevator, (or service elevator, cargo elevator, or goods lift in china) is an elevator designs to carry goods, rather than passengers.

Freight elevators are generally required to display a written notice in the car that the use by passengers is prohibited (though not necessarily illegal), though certain freight elevators allow dual use through the use of an inconspicuous riser.

Freight elevators are typically larger and capable of carrying heavier loads than a passenger elevator, generally from 2,300 to 4,500 kg. Freight elevators may have manually operated doors, and often have rugged interior finishes cab (which called enclosure) to prevent damage while loading and unloading. Although hydraulic freight elevators exist, traction elevators are more energy efficient for the work of freight lifting. These elevators are specially constructed to withstand the rigors of heavy loads.

Classes of freight elevator  

Class A: General Freight Loading

Freight elevator with this class has the load distributed, the weight of any single piece is not more than 1/4 the capacity of the elevator and the load is handled on and off the car platform manually or by means of hand trucks.

Class B: Motor Vehicle Loading

Freight elevator with this class is used solely to carry automobile trucks or passenger automobiles up to the rated capacity of the elevator.

Class C1: Industrial Truck Loading

A four-wheeled vehicle may be used to load and unload in the elevator with this class. The combined weight of the vehicle and the load cannot exceed the rated capacity and may be rolled onto the platform as a single unit.

Class C2: Industrial Truck Loading

In this class, during loading and unloading, the maximum load on the platform may be up to 150% of the rated capacity. This enables the user to use a forklift to load a car with freight weighing up to the rated capacity.

Class C3: Other forms of Industrial Truck Loading

During the loading and unloading process, the rated capacity must never be exceeded.

Doors

Door configuration in some smaller freight elevators are normally center-opening or two sliding telescopic doors, Larger freight elevators normally have three or four sliding telescopic doors.

Very large or heavy-duty freight elevators with very large capacity (up to 7000 kg) may have six-sliding telescopic doors.

Safe elevator china have designed a large capacity up to 10000kgs. 

Vehicle elevator

A vehicle elevator (or car lift) is used within buildings or areas with limited space (in lieu of ramps), typically to move cars into the parking garage or manufacturer's storage. Vehicle elevators are mostly hydraulic drive and have a weight capacity of 2 tons.

Geared hydraulic chains (not unlike bicycle chains) generate lift for the platform and there are no counterweights. To accommodate building designs and improve accessibility, the platform may rotate so that the driver only has to drive forward.

Dumbwaiters

Dumbwaiters are small freight elevators intended to carry objects rather than people. Dumbwaiters are found within modern structures, including both commercial, public and private buildings, are often connected between multiple floors. When they are installed in restaurants, schools, hospitals, libraries, retirement homes or in private homes, the dumbwaiter generally terminate in a kitchen.

Ultra-floor elevator system selection

In the high-rise building, the fast, efficient, smooth vertical service is indispensable. Elevator equipment as a vertical transport, its number of configurations, the selected control mode and related parameters will not only directly affect the building of an investment in elevator invest about 10% of total investment in the building), but will also affect buildings the use of safety and operational quality of service ......

Key words：High-rise building  Elevator system  Select application

First.  High-rise elevator configuration

In the high-rise building, the proper selection of the numbers of elevator, capacity, speed, control is very important, and once selected and elevator installation in a building almost become a permanent fact, if you want to increase or modification after is very difficult, even impossible, therefore, in the design should be in the beginning of the design configuration of the elevator should be full attention.

Generation of ultra-high-rise buildings, mostly in about 100 floors, large population movements in the building, the key longitudinal transport depends on elevators, efficient elevator design of high-rise building elevator is to use a variety of local elevator service, and the local area of the elevator system organized. Access to these local area, by the ground station to the originating local area air fast shuttle between lobby elevator service, air passenger arrival lobby then transfer to local elevators. To be able to transport passengers to reach their destinations as fast, generally every 30 to 35 layer construction is a local area.  

Super high-rise elevator in the configuration should pay attention to the following:

1.Limited numbers of viable elevator lift is a single group 8 units.

2.Number of floors located above each elevator floor area (office) should not exceed 15 to 16 layers (double layer is 18 to 20 floors)

3.A typical office building elevator load is single: 1350,1600 and 1800kg. Double is: 1350/1350; 1600/1600; 1800 / 1800kg.

4.Typical air corridor / sightseeing story elevator load 2040/ 2250/ 2500kgs.

5.The vertical acceleration of the elevator at 0.9 ~ 1.5m /s.

6.Elevator emphasis on speed to overcome a long stroke; a typical non-elevator speed gearbox is: 2.5,3.5,4.0,5.0,6.0,7.0,8.0,9.0,10.0m / s, etc.

7.Traction elevator longest stroke 600m.

Second.Layer super high-rise elevator control system
Since the high-rise building multi-elevator system, in order to improve the efficiency of the elevator group, with the fastest speed to meet the needs of passengers and shorten the waiting time of passengers, should be used to this end microcomputer elevator control system, processing large amounts of information through the computer control system in a timely manner various state judging information of each call and each elevator platform, directions, opening and closing state, call the car so as to improve transport capacity, improve service quality, enhance economic efficiency over the building.

Elevator group control microcomputer system mainly has the following aspects:

1.Each stop of the car cabin before it reaches the site should slow down,and forced slow down before it reaches the ends of the platform, stop and avoid the red top hit bottom, in order to ensure safety.

2.The passengers inside the car to reach the site by registering as a response signal lights, slow down before reaching the designated site parking, elimination number, and respond to registered signals call of waiting passengers.

3.Full load by pass, only the passengers in the car parked in the designated site.

4.When the car reaches a certain load from the platform, another platform call, the car with another car traveling in the same direction relatively to each layer distance call, the calling station arrived recently, and elimination No.

5.End platform passengers call, call the low-end car and the nearest platform of the empty car service.

6.In each car platform to set the display position of the platform passengers forecast eliminate passengers anxious mood, while allowing passengers to move in advance to the transponder elevator, to shorten waiting time.

7.After answering a landing call is registered, the car arrived at the site should have a voice to remind passengers waiting ladder.

8.Operation of the car scans the site of the deceleration point, according to the car or whether the site to decide whether to call parking.

9.Call passenger car platform, the same platform can provide elevator service to all transponders respond.

10.The control room make elevator group classification, the number of single-layer and double-stop-stop several layers, all elevators are in end station as the end point, in the middle of the hall, the singular layer station call double layers of the platform of the car, do not register the control room, without response.

11.Intermediate landing call elevators do not register, do not respond.

12.Complete car transport task, without instructions or call signal to perform other services, the elevator stop at the station, the car door open, waiting for the other call signal.

13.Control system monitor the status of the elevator control system in time, while scanning each station's call status.

Third.Ultra-high-rise high-rise elevator system power supply

Super high-rise elevators powered systems are generally configured two independent power supply to ensure that the elevator electricity to prevent power interruptions elevator leaving passengers stranded in the elevator traveling. When all the way to power failure or maintenance, another way Power Automatic. If an accident or a wide area of the second power outage can not supply, then the power supply system should be converted to the third power, high-rise a third supply is generally supplied from a diesel generator. When the third power supply also fails, and only rely on battery power, the battery will give the general public access requirements for each floor to provide emergency lighting and emergency power, the remaining power to the elevator, and the elevator can be maintained to continue to work.

Fourth.Elevator grounding system
After modern Elevator reference computer control system, elevator grounding system becomes complicated. It includes signal ground, safety ground lightning protection and grounding protection.

Fifth.Elevator weak system

In addition to the device itself with an elevator and some weak and various monitoring devices, in general, there are provided in the elevator car and the elevator machine room and duty room can intercom hot-line and emergency bell and other electronic equipment. Which features more than one elevator group control of the buildings also has run accident dashboard for monitoring elevator anomalies and emergency operations. Many of the buildings are now using a lot of computer systems, such as building automation system (BAS), fire alarm linkage control system (FAS), security monitoring system (SAS), these control systems have to achieve control of the elevator, its purpose is to strengthen the elevator management, improve elevator usage, reduce energy consumption, providing people with comfortable, efficient and safe environment.