Overload limiter is a safety protection device for bridge crane against overload, also called a weight limiter. Its safety function is to stop the lifting operation when the crane's suspension load exceeds the rated value, thereby avoiding accidents due to overload. Overload limiters are widely used on bridge type cranes and lifts. Some boom type cranes (such as tower cranes, portal cranes) use an overload limiter with a torque limiter. Overload limiters of eot crane include mechanical and electronic types.
(1) Mechanical type: The lever is driven by levers, springs, cams, etc. When overloaded, the lever reacts with a switch that controls the lifting action, cuts off the power source of the lifting mechanism, and controls the lifting mechanism to stop the operation.
(2) Electronic: It is composed of sensors, operational amplifiers, control actuators, load indicator, etc. It integrates display, control and alarm functions. When the crane is suspended, the sensor on the load bearing member is deformed, the weight of the load is converted into an electrical signal, and after operation is amplified, the value of the load is indicated. When the load exceeds the rated load, the power source of the lifting mechanism is cut off, so that the lifting operation of the lifting mechanism cannot be achieved.