VERTICAL CIRCULATION
LIFTS An appliances designed to transport persons or materials between two or more levels in a vertical direction by means of a guided car platform is called lifts/ elevators. OR An elevator or lift is a vertical transport vehicle that efficiently moves people or goods between floors of a building. They are generally powered by electric motors that either drive traction cables and counterweight systems, or pump hydraulic fluid to raise a cylindrical piston.
COMPONENTS OF LIFT The main components of an electric traction lift are in the following :
1. CAR The car is a cage having an external frame of steel channels , which is supported at the top by suspension ropes . The bodywork , which is fixed to the frame , may consist of suitable paneling material such as plywood , laminated board etc. with appropriate surface finishes to facilitate cleaning . A metal flushing sliding door (about 32 mm thick) is generally provided ; an electric door operator automatically opens and closes the door of the car.
2. GUIDE RAILS The steel guide rails , generally of tee section , up and down which the car traverses , must be truly vertical . They are screwed to brackets , which are rag bolted to the enclosure walls . Guide shoes of phosphor – bronze or gun metal ,are self – acting and spring – loaded and are fitted
centrally at the top and bottom of both sides of the car. These shoes fit the smooth surfaced rails to ensure that the car doesn’t “jump” the rails when in motion. Instead of sliding guide shoes , roller guide shoes may be used which have the advantage of not requiring lubrication of rail guides and thus promote cleanliness and reduce the fire risk.
3. COUNTERWEIGHT The counterweight consisting of thick steel plates balances the weight of the car together with 40-50% of live load. Self-acting guide shoes (two at each side) are bolted to the top and the bottom of the counterweight . It is usual for the counterweight to to be at the back of the car.
4. LIFT WIRE ROPES Suspension wire ropes have a high factor of safety are kept well oiled and are frequently inspected. The driving sheave or traction drive is mounted and connected to the motor. V – shaped grooves are formed on the face of the sheave and the suspension ropes from the car pass over the sheave in these grooves to the counterweight after they have been offset by the diverting pulley.
5. BUFFERS Spring buffers are provided on the pit floor with suitable foundations symmetrically underneath both car and counterweight to absorb or reduce the impact of both at the extreme bottom limit of travel. Only oil buffers shall be used with lifts having rated speed in excess of 1.5m/s.
6. OPERATION OF LIFT The ropes raise and lower the car in the lift well. The winding machine consisting of the motor , brakes , reduction gear and sheave are installed on a rigid base in the machine room above the lift well or in the basement. Motive power is electricity. Controller starts the motor in the required direction with the necessary acceleration and deceleration. There are four methods of control, a) Full automatic control by push button, b) car switch control, c) dual control , d)semi-automatic control every passenger and good lift must be provided with an emergency stop switch , a press button alarm and automatic safety gear on the car, which in the event of rope failure , will stop and sustain fully loaded car in the guides. If a car during its descent exceeds the maximum speed , the over speed governor comes into operation to the rope and thereby activating the safety gear.
TYPES OF LIFTS • • • •
Passenger lifts Goods lifts Hospital lifts Panoramic lifts
1. PASSENGER/TRACTION LIFTS A passenger elevator is designed to move people between a building's floors. SR.No.
LOAD PERSONS
CAR INSIDE
LIFT WELL
KG
A
B
C
D
ENTRANCE E
1
4
373
1100
700
1900
1300
800
2 3 4 5
6 8 10 13
408 544 680 884
1100 1300 1350 2000
1000 1100 1300 1100
1900 1900 1900 2500
1600 1900 2100 1900
800 800 800 900
2. GOODS / FREIGHT LIFTS
A freight elevator, or goods lift, is an elevator designed to carry goods, rather than passengers. Freight elevators may have manually operated doors, and often have rugged interior finishes to prevent damage while loading and unloading.
SR.No.
LOAD
CAR INSIDE
LIFT WELL
ENTRANCE
KG
A
B
C
D
E
1
500
1100
1200
1900
1500
1100
2
1000
1400
1800
2300
2100
1400
3
1500
1700
2000
2600
2300
1700
4
2000
1700
2500
2600
2800
1700
5
2500
2000
2500
2900
2800
2000
3. HOSPITAL LIFTS For simple transportation of a patient on wheelchair to wheeling away a critical patient on bed without disturbing his life support system with doctors & nurses attendance, smoothly & silently, without jerks & shocks. SR.No.
LOAD PERSONS
CAR INSIDE
LIFT WELL
KG
A
B
C
D
ENTRANCE E
1
15
1020
950
2400
1700
3000
800
2 3
20 26
1360 1768
1300 1600
2400 2400
2200 2300
3000 3000
1200 1200
4. DUMBWAITER LIFTS
Dumbwaiters are small freight elevators that are intended to carry food rather than passengers. They often link kitchens with rooms on other floors.
4. PANORAMICS LIFTS The panoramic lift applies both to external lifts on the facades of imposing business premises from which passengers ca enjoy the view and internal lifts in department stores or in foyers of large hotels where they look out on to the sales floors and displays.
TYPES OF HOIST MECHANISM Passenger lifts generally employ two kinds of hoist mechanisms :1. Traction lifts 2. Hydraulic lifts 1. TRACTION ELEVATOR : This type of lift is driven by Wire ropes passing over a driving wheel or sheave and connected to the lift car and a counterweight. The speed of these lifts can range from 0.5 m/s up to a maximum of 10 m/s. These machines are generally the best option for basement or overhead traction use for speeds up to 500 ft/min (2.5 m/s). Ropes are attached to the elevator car and looped around a hoist machine with deep grooves in its circumference known as a sheave. The sheave grips the hoist ropes, so when the sheave, which is connected to an electric motor, rotates, the ropes move too.
When the motor turns one way, the sheave raises the elevator; when the motor turns the other way, the sheave lowers the elevator. The counterweight is located in the hoist-way and rides a separate rail system; as the car goes up, the counterweight goes down, and vice versa. This action is powered by the traction machine which is directed by controller, typically a relay logic or computerized device that directs starting, acceleration, deceleration and stopping of the elevator cab.
The advantages of the traditional traction lift include:• • •
Fast speeds and efficient performance. Quiet, smooth ride. Available for high-rise applications.
The drawbacks of the traditional traction elevator include:• • •
Higher installation cost. Significant structural loads at the top of the hoist way. Elevator machine room required.
n
Traction elevator.
2. HYDRAULIC LIFTS • • • •
Hydraulic lifts work by the action of a pumped fluid, normally oil. Within a cylinder driving a piston which is attached to the lift car. The hydraulic lift is used in applications where the maximum travel distance is about 20m. The maximum traveling speed of commercially available hydraulic lifts is limited to about 0.75m/s. The hydraulic lift has the advantage of lower capital cost when compared with a traction lift Hydraulic systems are commonly used in low-rise buildings up to five stories. Speeds rarely exceed 150 feet per minute (fpm).
WORKING METHOD :
Originally the fluid used to drive the piston was water, hence the name hydraulic; today, the fluid is typically an oil-based “hydraulic fluid.” There are four major components to the hydraulic system: a tank (fluid reservoir); a pump powered by an electric motor; a valve between the cylinder and the reservoir; and the cylinder. The pump forces fluid from the tank into the cylinder. As the fluid collects in the cylinder, it pushes the piston up, lifting the elevator car. When the valve is opened, the pressurized fluid will take the path of least resistance and return to the fluid reservoir. When the car approaches the correct floor, the control system sends a signal to the electric motor to gradually shut off the pump and close the valve. With the pump off, there is no more fluid flowing into the cylinder, but the fluid that is already in the cylinder cannot escape (it can't flow backward through the pump, and the valve is still closed). The piston rests on the fluid, and the car stays where it is. To lower the car, the elevator control system sends a signal to the valve. When the valve opens, the fluid that has collected in the cylinder can flow out into the fluid reservoir. The weight of the car and the cargo pushes down on the piston, which drives the fluid into the reservoir. The car gradually descends. To stop the car at a lower floor, the control system closes the valve again.
TYPES OF HYDRAULIC LIFTS : 1. 2. 3.
In-ground system Holeless system Roped system
THE ADVANTAGES OF THE HYDRAULIC ELEVATOR INCLUDE:• No overhead machine room is necessary. • Elevator hoist way dimensions are optimized. • Loads are distributed to load bearing walls—there are no overhead structural requirements. • Machine rooms can be located remotely. • Installation costs are generally less than those for conventional traction roped systems. THE DRAWBACKS OF THE HYDRAULIC ELEVATOR INCLUDE:• Machine room needed for pump unit and control system. • Limited speed and performance. • High noise levels as compared to other systems. • Odour from heated oil. • Environmental concerns due to significant use of oil. • Poor ride quality as compared with other systems.
ESCLATORS • • • • •
An escalator is a conveyor type transport device that moves people. It is a moving staircase with steps that move up or down using a conveyor belt and tracks keeping each step horizontal for the passenger. They are provided where it is necessary to move large number of people from floor to floor in minimum of space. For example , at railway stations , airports etc. The escalators operate at a constant speed , serve only two levels and have a known maximum capacity , which varies from 3200 to 6400 persons per hour depending on the width of the escalators. Escalators are reversible in direction. They are generally operated at a speed of not more than 38m/minute.
COMPONENTS OF ESCALATORS : • An escalators consists of trusses or girders , the balustrade and handrails , and an endless belt with step treads and landings. • At the upper end of the escalators there is a pair of motor driven sprocket wheels and a worn gear driving machine. • At the lower end also there is a matching pair of sprocket wheels. Two precision made roller chains travel over the sprockets pulling the endless belt of step supported on four resilient rollers. • The structural framing is housed in escalator enclosure which is suitably rendered from outside to provide an aesthetic appearance.
DESIGN CONSIDERATIONS: ANGLE OF INCLINATION It shall not be in excess of 30° from the horizontal excepting that with an escalators having a vertical rise not exceeding 6m an angle upto 35° may be allowed.
WIDTH The width of the escalators is reckoned . The minimum and maximum width of the step tread being 400mm and 1020mm respectively.
BALUSTRADE Escalators shall be provided on each side with solid balustrade. Each balustrade shall be provided with a handrail moving in the same direction at substantially the same speed as the steps. Each moving handrail shall extend at normal handrail height not less than 30cm beyond the line of points of combplate teeth at the upper and lower landing. Hand or finger guards shall be provided at the point where the handrail enters the balustrade. The clearance on either side of the steps between the steps and the adjacent skirt guard of balustrade shall be not more than 5mm and the sum of the clearances on both sides shall not be more than 6mm.
COMBPLATES There shall be a combplate at the entrance and exit of every escalators. It is a pronged plate that forms part of an escalator landing and engages with the cleats of the steps at the limits of travel. The combplate teeth shall be meshed with and send into slots in the tread surface so that the point of the teeth are always below the upper surface of the treads.
TRUSSES OR GIRDERS: The truss or girder shall be designed to safely sustain the steps and the running gear in operation. In event of failure of the track system it shall retain the running gear in its guides.
STEP WHEEL TRACKS: These shall be so designed to prevent displacement of the steps and the running gear if a step chain breaks.
SAFETY DEVICES: Safety devices shall be provided to cause automatic interruption of power supply in case of failure of step chain , drive chain etc. An electrically released brake shall automatically stop the escalator when any of the safety device functions.
EMERGENCY STOP BUTTONS: These are manually operated switches having red buttons or handles conspicuously marked STOP PUSH OR STOP SWITCH. These shall be located at or near the top and bottom landings of each escalators.
DESIGN AND LAYOUT CONSIDERATIONS
A number of factors affect escalator design, including physical requirements, location, traffic patterns, safety considerations, and aesthetic preferences. Foremost, physical factors like the vertical and horizontal distance to be spanned must be considered. These factors will determine the pitch of the escalator and its actual length. The ability of the building infrastructure to support the heavy components is also a critical physical concern. Location is important because escalators should be situated where they can be easily seen by the general public. Furthermore, up and down escalator traffic should be physically separated and should not lead into confined spaces. The carrying capacity of an escalator system must match the expected peak traffic demand, presuming that passengers ride single file.
MODEL SIZES AND OTHER SPECIFICATIONS Escalator step width
Size
Width (Between Balustrade Panels), in mm
Very small
400 mm
Energy usage Width (Between Balustrade Panels), in Inches
16 in
Single-step capacity
Applications
Energy consumption, in Kilowatts
Energy consumption, in Horsepower
One passenger, with feet together
A rare historic design, especially in older department stores
3.75 kW
5 HP
Low-volume sites, uppermost levels of department stores, when space is limited
3.75 kW
5 HP
7.5 kW
10 HP
7.5 kW
10 HP
Small
600 mm
24 in
One passenger
Medium
800 mm
32 in
One passenger + one Shopping malls, package or one piece department stores, of luggage. smaller airports
Large
1000 mm
40 in
Two passengers — one may walk past another
Mainstay of metro systems, larger airports, train stations, some retail usage
ARRANGEMENTS OF ESCALATORS
Multiple parallel layout
Parallel layout Crisscross layout
Escalators have three typical configuration options:• parallel (up and down escalators "side by side or separated by a distance", seen often in multilevel motion picture theatres), • crisscross (minimizes structural space requirements by "stacking" escalators that go in one direction, frequently used in department stores or shopping centers), and • multiple parallel (two or more escalators together that travel in one direction next to one or two escalators in the same bank that travel in the other direction). • Escalators are required to have moving handrails that keep pace with the movement of the steps. • The direction of movement (up or down) can be permanently the same, or be controlled by personnel according to the time of day, or automatically be controlled by whoever arrives first, whether at the bottom or at the top (the system is programmed so that the direction is not reversed while a passenger is on the escalator).
