BS 2 Lift presentation 2

BUILDING SERVICES TWO (BLD60503)

VERTICAL TRANSPORTATION

SYSTEM

BUILDING | SERVICES | TWO (BLD60503)

Vertical Transportation System

Hydraulic lifts

Hydraulic Elevators - How Elevators Work _ HowStuffWorks.html

BUILDING | SERVICES | TWO (BLD60503)Hydraulic lifts





Hydraulic systems has 3 partsA tank (fluid reservoir)A pump, powered by an electric motorA valve between the cylinder and reservoir

BUILDING | SERVICES | TWO (BLD60503)Hydraulic liftsHow it worksLift car by hydraulic ram, a fluid driven piston mounted inside a cylinderCylinder connected to a fluid pumping system (Oil)Pump forces fluid from the tank into the cylinder through pipeWhen valve is opened, pressurized fluid return to the reservoir


When valve is closed, fluid flow into the cylinderAs the fluid collects in the cylinder, it pushes the piston up, lifting the elevator car.When the car approaches the designated floor, the control system sends a signal to the electric motor to gradually shut off the pump


The fluid remain in the cylinderPiston stays on the fluid and the car remain still.To lower the car, the elevator control system sends a signal to the valve The valve is operated electrically by a solenoid switch

BUILDING | SERVICES | TWO (BLD60503)Hydraulic lifts – usage

Most suitable for slower speed operation (0.2 to 1 m/s)Shorter travel distance (20 to 24m)Suitable for hospitals and retirement homes – motion is smooth and almost jerk free.Popular for shopping centres and for refurbishment schemes – where headroom is limited

BUILDING | SERVICES | TWO (BLD60503)Hydraulic Lift System – Direct acting hydraulics

BUILDING | SERVICES | TWO (BLD60503)Hydraulic Lift System – Side acting hydraulics

BUILDING | SERVICES | TWO (BLD60503)Hydraulic Lift System -





BUILDING | SERVICES | TWO (BLD60503)Principal advantages of hydraulic lifts:

Lift loads directly transmitted to the ground. Motor room can be anywhere nearby. Save on structural costs if building height kept

minimum.Simplicity of operation reduces maintenance costsNo brakes or windings are necessaryCables or pulleys are not always required.

BUILDING | SERVICES | TWO (BLD60503)Principal advantages of hydraulic lifts:

Motor room is relatively small or not needed.No counterweight; larger lift carAccurate floor levelling is possible (important in hospitals & old people’s home)


Safety requirements For Electric Lifts:

BUILDING | SERVICES | TWO (BLD60503)Safety requirements

For electric lifts:Substantial enclosure for the carGates and locks that remain locked until the car is stationery.Automatic devices to prevent over-runningBuffers in the pit for car and counterweightCar suspended by at least separate cablesEmergency brakes operating on guides capable of supporting the car in the event of total cable breakage.

BUILDING | SERVICES | TWO (BLD60503)Safety requirements

For electric lifts:Alarm or telephone for emergency with a separate power supplyAdequate ventilation and lightingSafety exit should have an interlock to prevent lift moving if the safety exit is open.Over-speed governors are used and their operation causes the motor, brake and emergency guide brakes to operate simultaneously.Upper and lower terminal switches to stop over running also cause emergency brake operation


Lift Car Construction


Lift cars designed to serve one storey at a time Internal finishes

wide range of finishes to match interior design Strong and durable lasting for many years of wear and tear

Cars made of steel frame with mild steel panels having cellulose paint finish.

Alternative – demountable and replaceable panels can be fitted.

Floor finishes: passengers lift – easily cleanable

goods lift – steel plate for strength and impact resistance


No open panels permitted in enclosure (except ventilation panels) within .8m of car floor.

Openings in ventilation panel should not exceed 13mm

Fan ventilation is also used. Minimum height for car is 2m


Lift doorsTwo sets of lift doors are required for each lift entrance/exit:

Car doors fitted to the car; Landing doors fitted to the lift shaft enclosure

Landing doors form part of fire compartment and have appropriate fire resistance rating to BS 476. Qualified maintenance personnel have special keys to release the landing doors for access to shaft.On locking the doors, electricity supply is cut off and disables lift.


Doors may be:Single side openingTwo speed side openingSingle speed centre openingTriple speed side openingTwo speed, centre opening


BUILDING | SERVICES | TWO (BLD60503)Lift Doors

https://youtu.be/Bux6mzJovbw



BUILDING | SERVICES | TWO (BLD60503)Lift Door

BUILDING | SERVICES | TWO (BLD60503)Door control:Vertical infra red beamsUltra sonic sensors or electro static passenger detection

BUILDING | SERVICES | TWO (BLD60503)Guides

Shoes or Roller assemblies


Car and Counterweight buffersOil loaded buffers – for lifts having speeds of 1.5m/s or overSpring buffers – for speeds of between 0 and 1m/sTimber or cellular polyurethane buffers for slow speed lifts – between 0 and 0.25 m/s

BUILDING | SERVICES | TWO (BLD60503)Car and Counterweight buffers

Buffer design to stop a descending car or counterweight beyond its normal limit andTo soften the force with which the elevator runs into the pit during emergency


Door drive systems


Door drive systems

Fixed speed systems – driven by ac motors - used mainly on low to medium

speed small capacity lifts with a less intensive duty demand.

High speed, fully adjustable systems • Use controllable dc motors – permit optimum tuning to

applications• Energy efficient • Consistent door cycle times


Door drive systems

Door closing• Safety requirements – car drive system may not start

while doors are open• Limit kinetic energy of closing doors of two panels,

centre opening door 1100mm wide take 2.5 seconds to close

• Same size single panel side opening door take about 4 seconds


Door drive systems

Door opening• Permitted to begin door opening when car

approaching 0.25m of final stop to reduce transfer time.

• Higher performance installations – permit to open doors at much high speed than for closing

• Single panel, centre opening door 1100mm wide to open in 1.5 seconds


Tutorial

1.Compare the internal finishes of the lift car by 3 elevator companies. 2.Compare the door drive systems of lift car by 3 elevator companies.

BUILDING | SERVICES | TWO (BLD60503/QSB2714)Vertical Transportation System

The End

BS 2 Lift presentation 2

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