Building Services/Vertical Transportation/Lifts
Lifts are typically used for two purposes – passengers and goods. Passenger lifts, as the name suggests, are designed primarily for moving people although they are often used for moving small hand trolleys, persons in wheelchairs and sometimes prams/pushchairs. Passenger lifts in hospitals are often large enough to accommodate a hospital bed. Passenger lifts nearly always have sliding automatic doors although in smaller buildings, they may have a hinged door. In both cases, a safety interlock is fitted that prevents the lift from moving while the doors are open.
In most medium sized office buildings, separate good lifts are not required as most goods are small enough to fit in passenger lifts, however industrial sites, mixed use complexes and large retail stores often have a need for separate goods lifts. The smallest goods lift can generally accommodate a pallet plus pump truck. It is vital when sizing a goods lift to make sure that the equipment used for moving pallets can fit in the lift as well unless all floors served have their own moving equipment. Electrically assisted pedestrian operated pallet movers typically require more space than a manual pump truck and the extra weight of these should also be taken into account as they can weigh up to a ton! It is also useful to consider the weight of the operator in the lift as well.
Smaller goods lifts typically utilise automatic sliding doors in the same manner as passenger lifts, however larger lifts often utilise sliding concertina doors that must be opened and closed by the operator but like the passenger lift, there is usually a safety interlock to prevent the lift from moving unless the doors are closed. Similarly, the door is locked while the lift is moving for the safety of the occupants.
Goods lifts may have different controls to passenger lifts, a commonly installed feature is ‘Car Preference’ which enables the operator to insert a key into the lift’s control panel that stops it from responding to calls from other floors and only responds to buttons pressed within the lift car.
A specialist type of goods lift is the “Dumb Waiter”. Its name is derived from the traditional use of transporting food between a kitchen and serving area on different floors but essentially a dumb waiter is a lift that is too small for passengers and is only used for parcels or small items. A dumb waiter takes up less space and is cheaper to install than a full sized lift.
From a mechanical perspective, there are essentially three different types of lift – traction, hydraulic and stair lifts. These types will be described in detail in a separate module.