LImit Switch of Crane
Limit switch is an important part of the safety of Overhead Crane. The limit switch is electromechanical equipment, which can adjust all the equipment from household appliances to industrial machinery. For bridge cranes, they provide a solid reference basis for maintenance efficiency, reliability and safety standards.
Understanding the working mode of the limit switch is very important to understand the working mode of the crane and how these established settings make the crane run safely and effectively.
In some cases, there may be multiple limit switches associated with crane operation, such as crane movement or lifting motion. The first switch will signal that the safe travel limit is approaching and slow down the movement of the crane. The subsequent switch will indicate that the end of the safe travel distance has been reached and stop the movement.
H Type Limit Switch for Crane,Cross Limit Switch,Lifting Limit Switch Eurocrane (China) Co., Ltd. , https://www.eurocranegroup.com
First, in the selection of equipment above
Soft and hard-sealed gate valves are mainly based on process media, temperature and pressure, general media containing solid particles or having a wear or a temperature higher than 200 degrees is the best choice for hard sealing, caliber greater than 50 valve differential pressure is also considered to open the valve moment size When the torque is large, the fixed hard-sealed gate valve should be used. The sealing grade of the soft and hard seal can reach 6 levels.
Second, the use of conditions
Soft seals can generally achieve high seals, while hard seals can be as high or low as required; soft seals require fire protection, because at high temperatures, soft seal material will leak, and hard seal does not have this problem; hard seal Generally speaking, high pressures can be done, but soft seals are not. Soft seals cannot be used in some applications (such as some corrosive media) due to the problem of flowing media. Finally, hard seal valves are generally more expensive than soft seals. As far as manufacturing is concerned, the difference between the two is not significant. The main difference is the valve seat. The soft seal is non-metal, and the hard seal is metal.
Third, the manufacturing process
Due to many chemical and mechanical industries, the working environment is more complicated, and many of them are high temperature and high pressure. The frictional resistance of the medium is large and corrosive. Now that the technology has been improved, the use of various materials is better, and processing and other aspects can be followed. On the hard-sealed ball valve has been widely promoted.
In fact, the principle of the hard-sealed gate valve is the same as that of the soft seal. However, due to the fact that it is a seal between metals, the relationship between the hardness of the metals, the operating conditions, and the medium to be taken should be taken into consideration. Hardening treatment is generally required, and the balls and the seat must be constantly ground to achieve sealing. Hard-sealed gate valves have a long production cycle and are complicated to process. Hard-seal ball valves are not easy to do.
Fourth, on the sealing material
The flexible soft seal gate valve and the hard seal gate valve are the seal materials for the valve seat. The hard seal is precisely machined with the seat material to ensure the accuracy of the valve core (sphere). Stainless steel and copper are generally used. Soft sealing means that the sealing material embedded in the valve seat is a non-metallic material. Because the soft sealing material has a certain degree of elasticity, a relatively hard sealing of the processing accuracy will be low.
Function
In addition, the limit switch can prevent the crane from lifting loads exceeding the rated capacity. Another limit switch prevents the hoist from reaching the upper pulley and Cable Drum. There is another type that can prevent the motor from overheating.
If there is no overhead crane limit switch, the potential harm is very great. Therefore, each limit switch should be checked and maintained regularly.
When they open or close the circuit, the limit switch will wear out over time. In order to monitor wear and replace the switch before it fails, check the limit switch every day before using the crane.