University of Hail

Faculty of Engineering

Department of Architectural Engineering

Building Mechanical SystemsBuilding Mechanical Systems

ARE 322Lecture 6

Dr Azeddine Lakehal BELAKEHAL

2014-2015

Dr Azeddine Lakehal Belakehal

MECHANICAL CONVEYORSLIFTS, ESCALATORS AND LIFTS, ESCALATORS AND

TRAVELATORS

Lifts

Planning Lift Installations

To function efficiently and to provide access for the elderl y anddisabled, modern offices and public buildings are provided withsuitably designed lift installations.

Planning (as with all services) should commence early in the designprogram .program .

Priority must be given to locating lifts centrally within a building tominimize horizontal travel distance.

Consideration must also be given to position , relative to entrancesand stairs . Where the building size justifies several passenger lifts,they should be grouped together.

In large buildings it is usual to provide a group of lifts near themain entrance and single lifts at the ends of the building.

The lift lobby must be wide enough to allow pedestrian traffic tocirculate and pass through the lift area without causingcirculate and pass through the lift area without causingcongestion .

For tall buildings in excess of 15 storeys, high speed expresslifts may be used which by-pass the lower floors.

Requirements:

•Necessary in all buildings over three storeys high.

•Essential in all buildings over a single storey if they are accessed by the elderly or disabled . the elderly or disabled .

•Minimum standard : one lift per four storeys.

•Maximum walking distance to access a lift : 45 m .

•Floor space and lift car capacity can be estimated at 0.2m 2 per person .

Lift speed

* Express lift that does not stop at the lower floor levels. The upper speedlimit is 7 m/s because of the inability of the human ear to adap t to rapidchanging atmospheric conditions.

1 Overall theoretical maximum travel distance is 21m vertica lly, thereforelimited to four or five storeys.

Roping Systems for Electric Lifts

High tensile steel ropes are used to suspend lift cars.

They have a design factor of safety of 10 and are usually at lea st fourin number .in number .

Ropes travel over grooved driving or traction sheaves and pu lleys.

A counterweight balances the load on the electric motor and t ractiongear.

Methods for roping vary:

Single wrap 1:1 : the mosteconomical and efficient ofroping systems but is limitedin use to small capacity cars.

Single wrap 1:1 withdiverter pulley: required forlarger capacity cars.It diverts the counterweightaway from the car. Toprevent rope slip, thesheave and pulley may bedouble wrapped.

Single wrap 2:1 : an alternative for use with larger cars. Thissystem doubles the load carrying capacity of the machinery butrequires more rope and also reduces the car speed by 50%.

Double wrap: used to improve traction between thecounterweight, driving sheave and steel ropes.

Single wrap 3:1 : used for heavy goods lifts where it is necessaryto reduce the force acting upon the machinery bearings andcounterweight. The load carrying capacity is increased by u p tothree times that of uniform ratio, but the capital costs are higherwith increased pulleys and greater length of rope. By compar ison,the car speed is also reduced to one-third.

Drum drive : a system with one set of ropes wound clockwisearound the drum and another set anti-clockwise. It is equallybalanced, as one set unwinds the other winds. The disadvanta geof the drum drive is that as height increases, the drum becomesless controllable, limiting its application to rises of abo ut 30 m.

Compensating rope and pulley : used in tall buildings where t heweight of the ropes in suspension will cause an imbalance onthe driving gear and also a possible bouncing effect on the ca r.The compensating ropes attach to the underside of car andcounterweight to pass around a large compensating pulley atlow level.

Single Automatic Lift Control

The single automatic push button system is the simplest and leastsophisticated of controls. The lift car can be called and use d byonly one person or group of people at a time. When the lift car i scalled to a floor, the signal lights engraved `in use' are ill uminatedon every floor. The car will not respond to any subsequent lan dingcalls, nor will these calls be recorded and stored. The car is undercomplete control of the occupants until they reach the requi redfloor and have departed the lift.

The `in use' indicator is now switched off and the car is avail able torespond to the next landing call. Although the control syste m issimple and inexpensive by comparison with other systems, it has itslimitations for user convenience. It is most suited to light trafficconditions in low rise buildings such as nursing homes, smal lhospitals and flats.

Down Collective Lift Control

Down collective: stores calls made by passengers in the car a ndthose made from the landings. As the car descends, landing callsare answered in floor sequence to optimize car movement. If the caris moving upwards, the lift responds to calls made inside the car infloor sequence .floor sequence .

After satisfying the highest registered call, the car autom aticallydescends to answer all the landing calls in floor sequence .

Only one call button is provided at landings. This system is mostsuited to flats and small hotels, where the traffic is mainly betweenthe entrance lobby and specific floors

A variation in which car and landing calls are immediately st ored in

any number. Upward and downward intermediate landing calls are

registered from one of two directional buttons . The uppermost and

Full or directional collective

registered from one of two directional buttons . The uppermost and

lowest floors only require one button. The lift responds to c alls in

floor order independent of call sequence , first in one direction and

then the other. It has greater flexibility than the down coll ective

system and is appropriate for offices and departmental stores

where there is more movement between intermediate floors.

Controls for Two or More Cars

Two cars may be co-ordinated by a central processor to optimi zeefficiency of the lifts. Each car operates individually on a full ordown collective control system . When the cars are at rest, one isstationed at the main entrance lobby and the other, which has callpriority, at a mid-point within the building or at another co nvenientfloor level .floor level .

The priority car will answer landing calls from any floor except theentrance lobby. If the priority car is unable to answer all ca lldemands within a specific time, the other car if available wi llrespond.

A similar system may also apply to three cars, with two stationaryat the entrance lobby and one available at mid-point or the to p floor.

With the supervisory controlsystem, each car operates on fullcollective control and will respondto calls within a dedicated zone.

A micro-processor determinestraffic demand and locates carsaccordingly to each operatingzone.

Lift Doors

Door operation is by an electric motorthrough a speed reduction unit, clutchdrive and connecting mechanism . Thetype of entrance and doors form a vitalpart of the lift installation. The averagelift car will spend more time at a floorduring passenger transfer time than itwill during travel.

For general passenger service, either side opening, two-

speed or even triple-speed side opening doors are preferred .

The most efficient in terms of passenger handling is the two- speed

centre opening. The clear opening may be greater and usable c lear

space becomes more rapidly available to the passengers.

Vertical centre-bi-parting doors are suitable for v ery wide openings,

typical of industrial applications.

Lift Machine Room and Equipment

Wherever possible the machineroom should be sited above thelift shaft. This location minimizesthe length of ropes andoptimizes efficiency.

The room should be ventilated,but the vent opening must notbut the vent opening must notbe over the equipment.Machinery must be well securedto a concrete base.

To reduce sound transmissionand vibration, compressed cork,dense rubber or a compositelayer is used as an intermediatemounting.

A steel lifting beam is built intothe structure above the machineryfor positioning or removingequipment for maintenance andrepair.

Sufficient floor space is necessaryfor the inspection and repair ofequipment.

To prevent condensation the roommust be well insulated and heated.Walls, ceiling and floor should besmooth finished and painted toreduce dust formation. A regularpattern of room cleaning andmachinery maintenance should bescheduled.

Details of an Electric Lift Installation

To satisfy the need for economies in lift manufacturing proc esses,

dimensions are limited. Therefore, architects will have to establish

passenger transport requirements as a preliminary design p riority.

The size of lift shaft will depend upon the car capacity and th e space

required for the counterweight, guides and landing door.

Shaft and pit must be plumb andthe internal surfaces finishedsmooth and painted to minimizedust collection. A smoke ventwith an unobstructed area of 0.1m2 is located at the top of theshaft.

The shaft is of fire resistant construction. This will be at l east 30 minutesand is determined by building function and size.

No pipes, ventilating ducts or cables (other than those spec ifically for the lift)must be fitted within the shaft.

A clearance is required at the top of the lift for car overtrav el.

Counterweight location is at the back or side of the car.

Typical Single Lift Dimensions

All dimensions in metres

Dimension E refers to the car door height.

Types of lifts

Paternoster Lifts

A paternoster consists of a

series of open fronted two-

person cars suspended from

hoisting chains. Chains run

over sprocket wheels at the

top and bottom of the lift

shaft. The lift is continuously

moving and provides for both

upward and downward

transportation of people in

one shaft.

Passengers enter or leave

the car while it is moving,

therefore waiting time is

minimal. Passengers will

have to be fairly agile,

which limits this type ofwhich limits this type of

installation to factories,

offices, universities, etc. It

is not suitable in buildings

that accommodate the

infirm or elderly!

When a car reaches its limit of travel in one direction, it mov es acrossto the adjacent set of hoisting chains to engage with car guid es andtravel in the other direction. In the interests of safety, ca r speed mustnot exceed 0.4 m/s.

Paternosters convey about 600 persons per hour. This type of lift

has the advantage of allowing passengers to begin their jour neys

undelayed, regardless of travel direction.

Simplicity of control gear adds to the advantages, resulting inSimplicity of control gear adds to the advantages, resulting in

fewer breakdowns by eliminating normal processes of stoppi ng,

starting, accelerating and decelerating.

They are most suited to medium -rise buildings.

Oil-hydraulic Lifting Arrangements

Direct acting:

The simplest and most effective method, butit requires a borehole below the pit toaccommodate the hydraulic ram. The ramaccommodate the hydraulic ram. The rammay be one piece or telescopic.

In the absence of a counterweight, the shaftwidth is minimized.

This will save considerably on constructioncosts and leave more space for general use.

Side acting :

The ram is connected to the side of the car. For large capacity cars and heavy goods lifts, two rams may be required, one each side of the car. A borehole is one each side of the car. A borehole is not necessary, but due to the cantilever design and eccentric loading of a single ram arrangement, there are limitations on car size and load capacity.

Direct side acting :

The car is cantilevered andsuspended by a steel rope.

As with side acting,As with side acting,limitations of cantileverdesigns restrict car size andpayload.

Car speed may be increased.

Indirect side acting :

The car is centrallysuspended by steel rope andsuspended by steel rope andthe hydraulic system isinverted.

Details of Oil-hydraulic Lift Installation

Originally, hydraulic lifts usedmains water supply as theoperating medium .

The main was pressurized froma central pumping station toservice lift installations inseveral buildings.

The oil-hydraulic system has oilpressure fed by a pump into acylinder to raise the ram and liftcar.

Each lift has its own pumpingunit and controller.

These units are usually sited at orThese units are usually sited at ornear to the lowest level served,no more than 10m from the shaft.

The lift is ideal in lower risebuildings where moderate speedand smooth acceleration ispreferred.

Car speed ranges from 0.1 to 1m/s and the maximum travel is

limited to about 21m. The lift is particularly suitable for g oods lifts

and for hospitals and old people's homes.

Most hydraulic lifts carry the load directly to the ground, t herefore as

the shaft does not bear the loads, construction is less expen sive

than for a comparable electric lift installation.

Lift performance

Lift performance depends on:

•acceleration ;•acceleration ;•retardation;•car speed;•speed of door operation; and•stability of speed and performance with variations of car lo ad.

The number of lifts will have an effect on the quality of service . Four

The assessment of population density may be found by allowin g betweenone person per 9.5 m 2 of floor area to 11.25 m 2 of floor area.

For unified starting and finishing times 17% of the populati on per fiveminutes may be used. For staggered starting and finishing ti mes 12% of thepopulation may be used.

The number of lifts will have an effect on the quality of service . Four18-person lifts provide the same capacity as three 24-perso n liftsbut the waiting time will be about twice as long with the three -cargroup.

The quality of service may be found from the interval of the group.25-35 seconds interval is excellent, 35-45 seconds is accep table foroffices, 60 seconds for hotels and 90 seconds for flats.

Further criteria for the comfort and convenience of lift users:

•Directional indication of location of the lift lobby for peo ple

unfamiliar with the building.

•Call buttons at landings and in the car positioned for ease of use

with unambiguous definition for up and down directions.

•Call buttons to be at a level appropriate for use by people wit h

disabilities and small children.

•Call display/car location display at landings to be favorab ly

positioned for a group of people to watch the position of all c ars and

for them to move efficiently to the first car arriving.

•Call lights and indicators with an audible facility to show w hich car

is first available and in which direction it is travelling.

•Lobby space of sufficient area to avoid congestion by lift us ers and

general pedestrian traffic in the vicinity.

Fire fighting Lifts

During the early part of the twentieth century, it became app arent thatthe growing number of high rise buildings would require spec ialprovisions for fire control.

The firefighting lift was conceived as a means of rapidly acc essing theupper floors. Early innovations prioritized the passenger lift by meansof a `break-glass' key switch which brought the lift to the gr ound floorimmediately.

This is now unlikely to be acceptable to building insurers an d the fireauthorities. It is also contrary to current building standa rds whichspecify a separate lift installation specifically for fire fighting purposes.

Special provisions for firefighting lifts:

•Minimum duty load of 630 kg.

•Minimum internal dimensions of 1.1 m wide, 1.4 m deep, 2.0 m high.

•Provision of an emergency escape hatch in the car roof.

•Top floor access time : maximum 60 seconds .•Top floor access time : maximum 60 seconds .

•Manufactured from non-combustible material.

•A two-way intercommunications system installed.

•Door dimensions at least 0.8 m wide, 2.0 m high of fire resisti ng

construction.

•Two power supplies: mains and emergency generator.

Structures with floors at a height greater than 18 m above fir eservice vehicle access (usually ground level), or with a bas ementgreater than 10m below fire service vehicle access, should h aveaccessibility from a purpose-made firefighting lift. All intermediatefloors should be served by the lift. Firefighting lifts for o thersituations are optional but will probably be required by the buildinginsurer.

Minimum number of firefighting shafts containing lifts:

Buildings without sprinklers :1 per 900 m2 floor area (or part of) of the largest floor.

Buildings with sprinklers:

< 900 m2 floor area = 1900 to 2000 m2 floor area = 2900 to 2000 m2 floor area = 2

> 2000 m2 floor area = 2 +1 for every 1500 m2 (or part of).

•Maximum distance of firefighting lift shaft to any part of a floor is60m.

•Hydrant outlets should be located in the firefighting lobby .

Vertical Transportation for the Disabled

A passenger lift is the most

suitable means for

conveying wheelchair

occupants between floor

levels. However, a platform

lift or a platform stair lift maylift or a platform stair lift may

be used if access is only

between two levels. Platform

lifts must not be used where

they would obstruct a

designated means of fire

escape on a stairway.

● Landing space in frontof lift doors should besufficient to allow awheelchair to turn andreverse into a lift car.

● Control/call panelshould be prominent andeasily distinguishable from

Lift provisions

easily distinguishable fromits background.

● Time delay on dooropening to be sufficient toallow wheelchair access.Doors fitted with areactivation device toprevent people and/orwheelchair from beingtrapped in closing doors.

•Control panel in lift carpositioned on a sidewall, at least 400 mmfrom a corner at aheight accessible whilstseated.

•Control panel floornumbers to be raisednumbers to be raisedon buttons to assist thevisually impaired.

•Audible announcementof the floor levelsserved to help peoplewith visual difficulties.

•Visual display of floorlevels served to assistpeople with hearingimpairments.

•Emergency telephones tobe provided with inductivecouplers for the benefit ofhearing aid users. Locationat an accessible height fromat an accessible height froma wheelchair.

•Alarm controls provided atan accessible height with avisual display to confirm thebell has responded for thebenefit of lift users withhearing difficulties.

Escalators

Escalators are movingstairs used to conveypeople between floorlevels. They are usuallyarranged in pairs foropposing directionaltravel to transport up to12000 persons per hourbetween them .

The maximum carrying capacity depends on the step width andconveyor speed. Standard steps widths are 600, 800 and 1000 m m,with speeds of 0.5 and 0.65 m/s.

Control gear is less complex than that required for lifts as t he motorruns continuously with less load variations. In high rise bu ildingsspace for an escalator is unjustified for the full height and the highspeed of modern lifts provides for a better service.

To prevent the exposed openingsfacilitating fire spread, a watersprinkler installation can be usedto automatically produce a curtainof water over the well.

An alternative is a fireproof shutteractuated from a smoke detector orfusible links.

Escalator Arrangements and Capacity

Escalator configurations varydepending on the required levelof service.

The one-directional single bankThe one-directional single bankavoids interruption of traffic, butoccupies more floor space thanother arrangements.

A criss-cross or cross-overarrangement is used for movingtraffic in both directions

Travelators

Travelators : also known as autowalks, passenger conveyors andmoving pavements. They provide horizontal conveyance for p eople,prams, luggage trolleys, wheelchairs and small vehicles fo rdistances up to about 300 metres.

Slight inclines of up to 12 ƒ are also possible, with some as gr eatas 18 ƒ , but these steeper pitches are not recommended for usewith wheeled transport.

Applications range from retail, commercial and stor e environments to exhibition centres, railway and airport terminal s.

Speeds range between 0.6 and 1.3 m/s, any faster wo uld prove difficult for entry and exit.

When added to walking pace, the overall speed is ab out 2.5 m/s.

There have been a number of experiments with different mater ials

for the conveyor surface. These have ranged from elastics, rubbers,

composites, interlaced steel plates and trellised steel.

The latter two have been the most successful in deviating fro m a

straight line, but research continues, particularly into p ossibilities

for variable speed lanes of up to 5 m/s. However, there could b e a

danger if bunching were to occur at the exit point.

Stair Lifts

Stair lifts have been used in

hospitals, homes for the

elderly and convalescent

homes for some time. In

more recent years,

manufacturers havemanufacturers have

recognized the domestic

need and have produced

simple applications which

run on a standard steel joist

bracketed to the adjacent

wall.

The Building Regulations

provides that staircases in all

future dwellings are designed

with the facility to

accommodate and support aaccommodate and support a

stair lift or a wheelchair lift.

This will allow people to enjoy

the home of their choice,

without being forced to seek

alternative accommodation.