Elevators are vertical transportation vehicles carrying […]
Elevators are vertical transportation vehicles carrying people and must be given top priority in safe operation. The safety of the elevator should first of all protect the personnel, and at the same time protect the elevator itself and the goods carried and the building where the elevator is located.
The hazards that may occur in elevators are generally: people are squeezed, impacted, and fall and shear occur; people are clicked, and the car strikes beyond the limit stroke; the car is overspeeded or falls due to broken rope; due to material failure and loss of strength Cause structural damage, etc.
In addition to fully considering the rationality and reliability of the structure, and the reliability of electrical control and dragging, the safety of the elevator also sets up special safety devices for various possible hazards.
1 Protection against overtravel
In order to prevent the elevator from malfunctioning due to control problems, the car will continue to run beyond the top or bottom end stations, and protection devices must be installed to prevent serious consequences and structural damage.
The protection device to prevent overtravel is generally composed of a forced speed switch, a limit switch and a limit switch that are located near the upper and lower end stations in the hoistway. The over-travel protection device can only prevent over-travel caused by control failures during operation. If the car over-travel is caused by slipping of the traction rope, failure of the brake or insufficient braking force, the protection device is powerless.
2 Protection against elevator overspeed and broken rope
The elevator will cause the car to overspeed and fall due to control failure, insufficient traction force, brake failure or insufficient braking force, and overloaded drag rope breakage. Therefore, reliable protection measures must be taken.
The protection device against overspeeding and rope breaking is a safety gear-speed limiter system. Safety gear is a mechanical device that stops the car (or counterweight) from moving downwards. Any elevator car suspended by wire rope or chain should be equipped with safety gear. When someone can enter the space under the pit, safety gear can also be set for the counterweight. Safety gears are generally installed on the bottom beam of the car frame and act on the guide rails in pairs.
The speed limiter is a device that limits the operating speed of the elevator and is generally installed in the machine room. When the car goes up or down overspeed, the elevator stops running through electric shock. When the down overspeed electrical contact action still cannot stop the elevator, after the speed reaches a certain value, the speed limiter mechanically moves, pulling the safety gear to clamp the guide rail to move the car Car stop; when the car (or counterweight) falls due to the broken rope, the safety gear is also pulled by the mechanical action of the speed limiter to stop the car on the guide rail. After the safety gear and speed limiter are activated, the car (or counterweight) must be lifted and adjusted by professionals before it can be used again.