On September 14, 2019, 1 college student at Huaqiao University died of asphyxiation after being stuck in an elevator; on September 16, a man in Wenzhou stepped on a foot and fell to the bottom of an elevator shaft.
At 12:23 p.m. on October 5, 2019, an elevator car stranded people in a commercial plaza in a city, stranding 16 people (including 2 young children).
On December 29, 2020, a woman in Ningbo suddenly fell from the 18th floor in an elevator and was stunned on the spot ……
The endless elevator fall accidents year after year are very alarming ……
Although the safety performance of elevators today is constantly improving, but mastering the knowledge of elevator safety and learning to save yourself in case of danger is the most important thing!
Since we were young, we have heard that we should press all the floor keys to deal with elevator malfunction, but it is really not necessary! This method may be really unscientific!
This method may not be scientific! “Know yourself, know your enemy, a hundred battles will not be dangerous”, only if you understand the structure and operation of the elevator, you can take the correct self-rescue measures when you encounter elevator failure, so as to avoid casualties caused by panic.
First of all, let’s understand the working principle of elevator
There are two ways to lift an elevator: hydraulic and traction type.
The working principle of these two ways is similar, both of them are made of traction rope with car and counterweight respectively (the following figure), winding on the traction wheel and guide wheel, traction motor drives the traction wheel to rotate through the reducer, and the traction force generated by the friction between traction rope and traction wheel realizes the lifting and lowering movement of car and counterweight to achieve the transportation purpose.
Schematic diagram of elevator operation
Visualize like this.
Elevator operation diagram
The common elevator traction rope in our daily life is 4-6, and according to the relevant national standards: traction rope in 3 or more than 3, its safety factor should not be less than 12; when the traction rope is 2, its safety factor should not be less than 16.
What is the safety factor?
It refers to the car with rated load stopping at the lowest level station, a wire rope of the minimum breaking load (that is, wire rope sampling in tension testing machine bearing, at least break a strand when the tension value) and this wire rope by the maximum force between the ratio.
So under normal circumstances by the wire rope breakage caused by the falling accident is basically impossible to happen!
In addition, the engineer also considered the elevator traction rope all broken or brake failure, designed a device to prevent overspeed and rope breakage, that is, the safety caliper – speed limiter system.
Through the safety elevator wire rope pulling the safety clamp to act, the safety clamp clamps on the guide rail to make the car or counterweight stop running and keep stationary.
Even if there is an extreme situation that all the wire ropes break, the car can be prevented from falling [1].
Safety clamp – speed limiter structure diagram
In simple terms, if all the elevator traction ropes really break and fall rapidly, the safety clamp device in the elevator will work at this time, which is installed at the bottom of the car, and the safety clamp can brake the car in an emergency to stop the car steadily, so as to protect the life of passengers and wait for rescue without worry.
So the security design of the elevator is generally enough to make us feel at ease and trust it!
In this way, elevator fall should be a relatively rare fault, so what about the suspected “elevator fall” encountered by some passengers?
There are three kinds of common elevator falls
NO.1 The start of the fall phenomenon generated by the weighing device error.
The elevator will provide the starting torque according to the load information displayed by the weighing device, that is, the starting capacity of the motor. When there is an error in the weighing device, there is a deviation in the starting torque, and the elevator will have a slight fall, and then the phenomenon of starting fall will be produced.
This kind of fall is normal because the force provided by the motor is not enough to pull up the people in the elevator when it is just started.
NO.2 Return to the base station after stopping in the process of operation.
This phenomenon is more common to be mistaken for the elevator falling down, and is also more likely to cause panic among passengers.
When the elevator is in operation, once the circuit fails (most of them are leveling sensor failures), the control system of the elevator will evaluate different situations, and as long as it thinks the failure is not serious, the elevator will choose the nearest leveling or return to the base station (usually the first floor) and open the door to release people.
At this point, passengers may mistakenly think that the elevator fell to the first floor, in fact, it is the opposite, this is a practice of the elevator to protect the safety of passengers, at this time, press the internal call button or the floor key is really useless, and may even cause interference.
NO.3 Insufficient braking force caused by brake failure or elevator overload, resulting in the elevator falling down, this situation can be considered a real elevator falling down fault.
But in actual situation, the elevator’s anti-fall and anti-speed system will emergency brake, which can protect our lives, so there is no need to panic.
In addition to car falls, there are also shaft falls
When the elevator does not arrive at the station, there are always people who, for whatever reason, “do not want anything, nothing is afraid” to open the door by external force and fall directly from the shaft.
Compared with the case of car fall, the consequences of such a fall is more serious, almost like jumping to suicide.
Most of the elevator accident casualties occur when trying to escape themselves!
When you find the elevator suddenly falling, if there is a handle inside the elevator, you must hold on to it and keep your own center of gravity smoothly to avoid falling down and being injured due to the impact.
If there is still space left in the elevator, quickly hands propped up against the elevator wall, back and head into a line, and close to the inner wall of the elevator, knees bent heel pad up posture can be used ligaments, play a cushioning role.
Never in the process of falling also to touch the floor keys one by one, or try to break open the elevator door!
Have you learned?
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