What is the purpose of a crane's load indicators or dynamometers?

• A. To measure crane fuel efficiency.
• B. To report worker fatigue levels.
• C. To monitor real-time load relative to rated capacity and provide warnings if a load is approaching or exceeding limits.
• D. To record the color of the load.

Answer: (C)

Understanding how load indicators and dynamometers work is about keeping crane lifts within safe limits. These devices measure the actual load being carried by the crane and compare it to the crane’s rated capacity for the current configuration (boom length and angle, radius, counterweights, etc.). They feed real-time readings to the operator and often trigger audible or visual alarms if the load is getting close to or exceeds the allowable limit.

The key purpose is to prevent overloading. By showing how close the load is to the rated capacity, they help the operator decide whether to proceed, adjust the setup (shorter reach, lighter load, different configuration), or stop the lift. Many systems also factor in dynamic effects, like acceleration, deceleration, and swing, which can make the actual force on the line higher than the static weight. Some controls even limit movement or derate the crane automatically to avoid tipping or structural damage.

So, the main idea is to monitor real-time load relative to what the crane can safely handle and to provide warnings or automatic safeguards to keep lifts within safe limits. These indicators aren’t meant for measuring fuel efficiency, tracking worker fatigue, or recording the color of a load.