A load moment indicator (LMI) / safe load indicator (SLI) is a device used in cranes and lifting equipment to provide real-time information about the load being lifted and ensure that it remains within safe operating limits. The primary purpose of a safe load indicator is to prevent overloading, which can lead to accidents, equipment damage, and potential injury or loss of life.

A safe load indicator typically consists of sensors, a display unit, and an alarm system. The sensors are strategically placed on the crane or lifting equipment to measure parameters such as load weight, boom angle, radius, and wind speed. These sensors transmit data to the display unit, which calculates the actual load and compares it to the safe working load (SWL) specified by the manufacturer.

The display unit shows the operator the current load information, including the weight of the load, the radius of the load, and the permissible limits. If the load exceeds the safe working load or if any other parameter goes beyond the safe operating limits, the alarm system is activated, warning the operator to take appropriate action, such as reducing the load or adjusting the crane's position.

Safe load indicators are essential safety devices in crane operations, as they help prevent accidents caused by overloading, instability, or unfavorable operating conditions. They provide operators with real-time feedback, enabling them to make informed decisions and maintain safe working conditions.