What do you fear most when taking an elevator? Sudden stop, sharp rise or sharp fall?
Most people would choose the latter two. After all, if it is out of service trapped in it, you can also call the maintenance personnel through the emergency button to rescue; If it's the latter two, you might just fall down injured and have trouble calling for help.
So, is it really that easy for elevators to rush up or down so fast?
The probability is 1 in 100,000 or less.
In fact, elevators have many safety devices, which are safeguarded by multiple layers of control.
Firstly, professional traction ropes with top-quality toughness,
secondly, a large number of safety switches from the machine room to the car top and pit to constitute a safety circuit, and also motor brakes, overspeed governor, safety gear, buffers and so on to limit the elevator's rapid up or rapid down.
If all other safety devices fail to work, the over speed will trigger the safety gear activate , which will clamp the guide rail and stop the elevator
Therefore, the elevator safety gear and speed governor are important items that must be inspected and tested for elevator installation, commissioning, acceptance, and final inspection.
Under normal circumstances, the safety gear and speed governor are linked action, the cause of the problem is many. In order to avoid the potential safety problems of elevator safety device, it is very important to explore the common problems of elevator speed limiting device and the relevant calibration technology.
Many reasons for the failure of elevator speed governor:
The rope length of the tensioning wheel of the speed governor is too long, which will cause the problem of dragging the floor and slipping. In the setting of speed limit, the setting value is higher than the setting design value, when the elevator in the process of overspeed operation, the role of the speed limit is difficult to play; After some old elevators are used for a long time, the lack of effective maintenance easy to cause the speed governor spring does not work, which affects the speed change of the speed governor. In the worn groove, the phenomenon of wire rope slipping appears.
At the same time, improper maintenance of the speed governor is easy to rust, which also leads to the elevator's electrical protection device or mechanical action can not operate normally, but also increase the resistance of the block, resulting in the failure of the speed governor.
In addition, there are some human reasons for the speed limit does not work, such as the wrong installation of the speed governor.
When the wire rope of the speed governor is extended, easy to cause the tensioning device to touch the pit ground, resulting in the problem of wire rope slipping due to insufficient tension.
In the process of daily maintenance and verification, it is necessary to confirm whether the wire elongation protection electrical switch can maintain the distance between the tightening weight and the ground within the effective running stroke.
In addition, the wheel brake parts of the elevator speed governor belong to wear parts, once not timely routine maintenance, will also cause the problem of rope lifting tension insufficient
As the spring of the speed governor retracts repeatedly for a long time, the speed of operation changes. At the same time, the electrical safety device has the problem of unreasonable clearance setting, which also leads to the speed limit can not operate normally between the mechanical parts.
In addition, a large number of debris and oil will also bring greater resistance to the rotating parts, resulting in the centrifugal swing part of the action is not accurate or flexible, can not meet the requirements.
When the speed governor or safety gear move beyond the range, the safety gear will cause excessive friction on the guide rail, resulting in the guide rail deformation.
At the same time, excessive oil and debris in the parts of the safety gear will also cause damage to the guide rail, and the wedge can not be automatically reset after the pulling arm is loosened.
In addition, the linkage failure may be caused by the quality problems of component design and manufacturing, the poor installation, debugging and matching of the safety gear of the speed governor, and the non-normal maintenance during the use of the device components due to wear, rust, fatigue and other conditions that lead to the change of action speed parameters or the weakening of function.
Therefore, it is particularly important to detect whether the function of the linkage security system is normal.