In the realm of mobile crane operations, ensuring safety is of utmost importance. One of the key safety features employed is the moment limiter, which plays a crucial role in preventing overloads and safeguarding both the crane and the surrounding environment. Mobile cranes generally utilize a complete set of moment limiters for effective overload protection.
The moment limiter is a complex system consisting of five main parts: the main unit, load detection, angle detection, length detection, and lifting condition detection. Each of these components works in harmony to provide comprehensive protection against overloading.
The load detection part is responsible for monitoring the weight of the load being lifted. This is achieved through the use of specialized load sensors that can accurately measure the force exerted on the crane’s lifting mechanism. These sensors send signals to the main unit, providing crucial information about the load being handled.
Angle detection is another essential aspect of the moment limiter. It measures the angle of the crane’s boom relative to the horizontal plane. This information is vital as it helps determine the effective lifting capacity of the crane at different angles. As the angle of the boom changes, the lifting capacity of the crane also varies. By continuously monitoring the angle, the moment limiter can ensure that the crane does not exceed its safe lifting capacity at any given angle.
Length detection is also crucial. It measures the length of the crane’s boom. Similar to angle detection, the length of the boom affects the lifting capacity of the crane. As the boom is extended or retracted, the lifting capacity changes. By accurately measuring the length, the moment limiter can adjust the allowed load based on the current boom length.
Lifting condition detection monitors various aspects of the lifting operation, such as the speed of lifting, the stability of the crane, and any abnormal vibrations or movements. This information is sent to the main unit to help determine if the lifting operation is being carried out safely.
All the detection signals from these different components are sent to the main unit by detection sensors. These sensors are highly sensitive and accurate, ensuring that the main unit receives reliable data. Once the signals reach the main unit, they undergo amplification, operation, and processing.
The amplification stage increases the strength of the signals so that they can be easily processed by the computer within the main unit. The operation and processing steps involve analyzing the signals, extracting relevant information, and comparing it with the pre-stored lifting characteristic curve in the computer.
The pre-stored lifting characteristic curve is a set of data that represents the safe operating limits of the crane based on various factors such as load, angle, length, and lifting conditions. By comparing the real-time detection signals with this curve, the control unit can determine if the crane is operating within safe limits.
If the detected signals indicate that the crane is approaching or exceeding its safe lifting capacity, the control unit takes appropriate action. This may include issuing warnings to the operator, reducing the lifting speed, or even stopping the lifting operation altogether. The control unit acts as the brain of the moment limiter system, making decisions based on the processed data to ensure the safety of the crane and the surrounding environment.
For example, imagine a mobile crane lifting a heavy load at a certain angle and boom length. The load detection sensor measures the weight of the load, the angle detection sensor determines the boom angle, and the length detection sensor measures the boom length. These signals are sent to the main unit, where they are amplified and processed. The control unit compares the processed signals with the pre-stored lifting characteristic curve. If it is determined that the load is close to or exceeds the safe lifting capacity for the given angle and length, the control unit may issue a warning to the operator, such as a flashing light or an audible alarm. The operator can then take appropriate action, such as reducing the load or adjusting the boom angle and length.
In conclusion, the moment limiter for mobile cranes is a sophisticated system that provides essential overload protection. By integrating load detection, angle detection, length detection, and lifting condition detection, and comparing the detected signals with a pre-stored lifting characteristic curve, the moment limiter ensures the safe operation of mobile cranes. This not only protects the crane from damage but also safeguards the lives and property of those working around the crane.
