Elevator Working Principle (Traction Elevator)
Most commercial and residential elevators are traction elevators. They operate based on friction traction and mechanical balance, which is safe, energy-saving and stable.
1. Core Structure
A traction elevator mainly consists of a traction machine, control cabinet, steel ropes, car (cabin) and counterweight. The steel ropes hang over the traction sheave. One end connects to the elevator car, and the other end connects to the counterweight.
2. Basic Operating Principle
The counterweight is designed to balance the weight of the car and about half of the rated load. This balance reduces the load of the motor and saves energy. When passengers select floors or press hall buttons, the control cabinet receives signals and sends operating commands.
When the elevator starts, the brake releases, and the traction motor drives the traction sheave to rotate. By the friction force between the sheave and steel ropes, the ropes are driven to move. The car and the counterweight run in opposite directions - one goes up while the other goes down.
During operation, sensors in the shaft detect the floor position to achieve accurate leveling. After leveling, the door machine drives the car door, which links and opens the hall door. The elevator can only restart after all doors are fully closed and locked.
3. Main Safety Protection Principles
- Brake system: The brake holds the traction wheel tightly in normal state. It locks the elevator immediately when power cuts off or faults occur to prevent slipping.
- Governor & Safety Gear: If the car overspeeds, the speed governor triggers the safety gear, which clamps the guide rails firmly and stops the car mechanically.
- Buffer: Installed at the bottom of the shaft to absorb impact energy and protect the car from hard landing.
- Limit & Final Limit Switches: Prevent the elevator from over-traveling (roof crashing or bottom hitting).
- Door Lock System: The elevator cannot start if any car door or hall door is not completely closed and locked.
The simple summary is：
Under the control of the electric cabinet, the traction machine drives the steel ropes by friction traction. The balanced car and counterweight move up and down along the guide rails, and multiple safety devices ensure stable and safe elevator operation.
