History: from the lift operator to the dispatcher

1850s — a safe lift. Hoists for goods had existed for a long time, but people were afraid to ride them: the rope could break. In 1854 Elisha Otis showed a safety brake at an exhibition in New York — a catch that holds the platform if the rope is cut. Three years later the first passenger lift with such a brake started working in a New York store — driven by a steam engine.

safety brake1854the rope breaks —the car holdselectric motor1880Siemens,Mannheimoperatoruntil 1950sthe logic isin a headgrouprelaysa floor scanner,no operatorprocessorlate 1970schoosing a caris a programwe build the relay stage — from transistors
A century and a half of lifts: from the safety brake that holds the car if the rope breaks to the program that chooses which car goes.

1880 — electricity. Werner von Siemens built the first lift with an electric motor in Mannheim. Houses began to grow upwards: height was no longer limited by the stairs.

The operator. For a long time a person drove the car — the lift operator. The operator listened to where people were going, watched the signals from the floors and steered the car with a lever, stopping it level with the floor. The logic "where to go next" was in the operator's head.

The automatic lift. Then the buttons in the car and on the floors began to control the lift by themselves, through relays: a press sets a relay, arriving at the floor resets it — exactly like our latches. Collective control appeared: the car picks up all the calls on its way. In houses with one call button per floor it is made "down collective": floor calls are taken on the way down.

A group of lifts

A tall building has several lifts, and if every car gets a call, every car goes. A dispatcher is needed. The first group systems were relay cabinets the size of a room: a scanner went round the floors and chose a car for every call. From the 1950s such systems made it possible to do without operators even in skyscrapers.

callsfloor buttonsdispatcherwho goes?car Acar Bcar Cone car gets the call — the cheapest
A group of lifts: floor calls go not to every car but to the dispatcher. It decides which car goes and gives the call to that car only.

The processor. In the late 1970s microprocessors came into lifts, and all the choosing logic became a program: the car price counts load, waiting time, rush hour. Later came destination dispatch: on the floor you type the floor you need, and the display tells you which car to go to.

We build exactly the relay stage, only from transistors: cars with collective control and a scanning dispatcher.