As the “brain” of large-scale engineering equipment, the core of a индикатор грузового момента крана lies in the accurate sensing of load and amplitude. The foundation of this is various sensors and their stringent numerical indicators. In complex lifting operations, sensors must not only withstand severe mechanical vibrations and temperature changes but also output accurate data within milliseconds to prevent overturning accidents. Therefore, in-depth analysis of the key numerical values of commonly used length, pressure, and angle sensors in load momnet indicators is crucial for understanding the equipment’s safety logic and improving monitoring accuracy.
Length sensors are the core components for calculating the crane’s working amplitude. Currently, the mainstream solutions on the market include potentiometer-type, wire encoder-type, and pulse encoder-type sensors. Among them, potentiometer-type sensors have a simple structure, but their numerical performance is limited by lifespan and accuracy. The output resistance variation range is typically 0 to 5 kiloohms, and the linear accuracy is often around ±0.5%. Furthermore, mechanical wear can cause resistance drift. In comparison, wire encoder sensors offer superior numerical performance, with resolutions reaching 0.1 mm or higher, repeatability controlled within ±0.05%, and output signals typically in the standard 4-20 mA or 0-10 V range, significantly enhancing anti-interference capabilities. For large all-terrain cranes, pulse encoders are the preferred choice due to their high reliability, with pulses per revolution (PPR) typically between 1000 and 2500. This means that even minute displacements during boom extension and retraction can be converted into precise digital pulses, ensuring amplitude calculation errors are controlled at the centimeter level.
Angle sensors monitor the boom’s elevation angle, directly determining the selection of the rated load curve. Dual-axis tilt sensors are currently the mainstream choice, with their core numerical indicators being measurement range and accuracy. Typically, these sensors have a measurement range of ±30 degrees or ±60 degrees, sufficient to cover the entire elevation angle range of crane operation. In terms of accuracy, high-quality sensors can achieve a measurement accuracy of ±0.1 degrees Celsius within the 0 to 40 degree Celsius range, and even after temperature compensation, the accuracy can be maintained within ±0.2 degrees Celsius across the entire temperature range (-40 to 85 degrees Celsius). This value is crucial because, under long-arm conditions, a 0.1-degree angle error can lead to a deviation of tens of centimeters in the horizontal position of the boom tip, thus affecting the accuracy of moment calculation. Furthermore, response time is also a key indicator, typically requiring less than 100 milliseconds to ensure that the system can capture angle changes in real time during rapid boom luffing.
Pressure sensors are mainly used to infer load weight by measuring hydraulic cylinder oil pressure, and are crucial for load moment indicators to obtain the “force” signal. Strain gauge pressure sensors are widely used due to their high overload capacity, and their range is usually set according to the crane tonnage, such as 25 MPa, 40 MPa, or 60 MPa. In terms of accuracy, industrial applications typically require an overall accuracy better than ±0.5%FS (full scale), while high-precision applications require ±0.25%FS. Besides static accuracy, the sensitivity and output signal stability of pressure sensors are equally important. A common sensitivity is 2 mV/V. Combined with a high-precision A/D conversion module, it can effectively identify minute fluctuations in hydraulic system pressure. Simultaneously, to cope with drastic changes in hydraulic oil temperature, the sensor’s zero-point temperature drift must be controlled within ±0.02%FS/℃, and the full-scale temperature drift within ±0.03%FS/℃. Otherwise, after prolonged operation leading to increased oil temperature, the load moment indicator is prone to false alarms or failure to operate.
Tension sensors are the core sensing devices in crane load moment indicator systems that directly monitor the lifting load. They are mainly used to collect the working tension of the wire rope in real time, accurately reflecting the actual lifting weight and effectively compensating for the calculation errors of indirect load measurement by pressure sensors. They are key components for improving the accuracy of moment monitoring and preventing overload operations, and are widely used in various mobile and tower cranes. Currently, the mainstream applications in the industry are wheel-type tension sensors and cantilever beam tension sensors, which are suitable for the complex operating conditions of dynamic lifting, luffing, and slewing of cranes, and have excellent impact resistance and wear resistance. Its measurement range can be precisely matched according to the crane’s tonnage specifications, typically covering mainstream specifications such as 5t, 10t, 20t, and 50t. Large engineering cranes can be adapted to large-range models with a capacity of hundreds of tons, comprehensively covering various lifting operation load ranges. In terms of core accuracy indicators, the industrial-grade crane-specific tension sensor has a static comprehensive accuracy of ±0.3%FS, and can stably maintain a measurement accuracy of ±0.5%FS under complex dynamic operating conditions, fully meeting the stringent standards for moment calculation. In terms of response speed, the sensor’s dynamic response time is less than 80 milliseconds, enabling it to capture sudden tension changes during lifting, load fluctuations, and luffing slewing processes in milliseconds, and to synchronize equipment operating data in real time. Meanwhile, to adapt to harsh outdoor operating environments such as high and low temperatures, vibration, and dust, the sensor’s operating temperature range is -35℃ to 75℃, with zero-point temperature drift controlled within ±0.03%FS/℃. It possesses excellent temperature stability and anti-interference capabilities, and outputs a unified 4-20 mA standard signal, allowing for precise compatibility with load moment indicator systems. Through dual data verification using direct load measurement and hydraulic load measurement, the reliability of crane operation safety monitoring is significantly improved.
In summary, the performance of a crane load moment indicator is not determined by a single component, but rather by the coordinated performance of the numerical indicators of four types of sensors: length, angle, pressure, and tension. From high-precision wire encoders and pressure sensors with extremely low temperature drift to highly sensitive angle sensors and dynamically stable tension sensors, each value represents an extreme pursuit of safety. In practical applications, only by fully understanding and matching the range, accuracy, resolution, and temperature characteristics of these sensors can a truly reliable torque limiting system be constructed, providing a solid safety guarantee for every lifting of large equipment.
