The working principle of the torque limiter system of truck crane and the key role of regular verification in preventing tipping accidents

Torque limiter is the most important safety protection device on truck cranes, and it is known as the “last intelligent line of defense for overload protection”.Its core role is to monitor the operating status of the crane in real time. Once it is determined that the current load is close to or exceeds the rated lifting moment under the working condition, it will automatically issue an alarm and cut off the movement in the dangerous direction, so as to effectively prevent tipping or structural damage accidents caused by overload.Understanding its working principle and ensuring the accuracy of its regular verification is the top priority to ensure the safety of lifting operations.

The torque limiter system usually consists of three parts: a sensor, a controller, and a display.The sensor is responsible for collecting key parameters: the arm length sensor (usually installed in the telescopic cylinder or arm head) detects the current arm length; the angle sensor (installed at the root of the basic arm) detects the elevation angle of the boom; the pressure sensor (installed in the luffing cylinder or the hydraulic circuit of the lifting hoist) detects the lifting load.Sometimes it also includes an amplitude sensor.The controller (computer) receives these signals and calculates the rated lifting weight at the current arm length and angle in real time based on the built-in lifting performance curve database corresponding to the characteristics of this model, and compares it with the actual lifting weight measured by the pressure sensor to obtain the “load rate” (actual load/rated load).The display visually displays these data to the operator, such as arm length, angle, amplitude, actual load, rated load, and load rate.When the load rate reaches a preset alarm value (such as 90%), the system will issue a sound and light warning; when it reaches 105%-110%, the system will automatically cut off the lifting, luffing, stretching and other actions that may cause the danger to increase further (such as continuing to lift, arm extension, and falling), but usually retain the safe direction of the action (such as falling hook, arm retraction, and lifting).

Regular verification is the only way to ensure that the torque limiter is always accurate and reliable.Calibration should be carried out by professionals, usually using standard weights or calibrated dynamometers.The verification cycle generally does not exceed one year, or should be carried out after the equipment is overhauled, the construction site is transferred, and important sensors are replaced.The verification content includes: checking whether the signal of each sensor is normal; under multiple characteristic working conditions (such as different arm lengths and amplitudes), load with weights of known weight, and verify whether the weight and load rate displayed by the system are consistent with the actual situation, and the error should be within the allowable range; check whether the alarm and shutdown functions are sensitive and reliable.After the verification is completed, a report should be issued and labeled.Any unauthorized adjustment, shorting or shielding of the torque limiter is absolutely prohibited.The operator should conduct a system self-check before daily operation to observe whether the display is normal.Treating the torque limiter as a partner for safety, not a yoke for efficiency, and insisting on regular verification by professional institutions, is the embodiment of the operator and manager's responsibility for life and property.