L46A1 Mast Section gravity moment limiter lifted from tower
During the use of Tower lifting, we should know more about the various parts of Tower lifting to ensure that the use of smooth. This paper introduces the working principle and function of the gravity moment limiter lifting from the lower tower.
Structure and working principle
The gravity moment limiter is divided into mechanical and electronic types, and there are many forms such as bar-slant and bow plate in the mechanical type. The bow plate type gravity moment limiter is widely used because of its simple structure. The bow plate torque limiter is mainly installed on the main strut of the tower cap.
Its working principle is as follows: When the tower is lifted to carry heavy weights, due to the effect of the load, the main string rod of the tower cap produces compression deformation, and the greater the load, the greater the deformation. At this time, the bow steel plate on the moment limiter is also deformed. And the deformation of the string is enlarged, so that the distance between the adjusting bolt and the limiting switch on the bow plate is gradually reduced with the increase of the load. When the load reaches the rated load, by adjusting the adjusting bolt to touch the limit switch, the power supply of the lifting mechanism and the changing amplitude mechanism is cut off, and the purpose of limiting the hanging gravity moment load of the tower crane is achieved.
The role of two gravity moment limiters
The lifting moment limiter is one of the important safety devices of Taidao. The structure calculation and stability verification of the tower crane are based on the maximum rated lifting moment. The function of the torque limiter is to control the tower crane when it is used. The maximum rated lifting moment is used to prevent overload.
The current national standard "Safety Regulations for Tower Cranes" stipulates that: Tower cranes should be equipped with gravity moment limiters. When the starting moment is greater than the corresponding working conditions and is less than 110 % of the rated value, the power supply in the direction of rising and increasing amplitude shall be cut off, but the mechanism may be able to move in the direction of falling and decreasing amplitude.
The torque limiter only limits the loading of the heavy moment in the vertical plane of the tower crane, and it does not work for the tilting moment in the water plane caused by the side sloping weight of the hook, the wind load in the water plane, the tilt of the track, and the collapse. Therefore, operators must strictly observe the safety operation rules and can not operate in violation of regulations.
