Views: 97 Author: Site Editor Publish Time: 2019-09-16 Origin: Site
In order to ensure the safety of lifting equipment and prevent accidents during lifting operations, various types of cranes are equipped with various safety devices of lifting equipment. Common protective devices include various types of stoppers, bumpers, anti-collision devices, anti-skew and skew indication devices, weight limiters, anti-overturning, wind protection and torque limiters.
The position limiter is a type of safety guard that limits the range of movement of each mechanism. It includes a limiter of rising, a limiter of running, a skew adjustment and the display device, and a buffer.
The limiter of rising is used for limiting the lifting height of the take-up device. When the spreader is raised to the upper position that is limited, the limiter cuts off the power supply, preventing the device of hook and the like from continuing to rise and pull the lifting chains to cause the heavyweight loss accident.
The lower limiter of rising is to cut off the power supply and stop the operation when the take-up device is lowered to the lowest position to ensure that the wire rope is wound around the reel with a safety ring of not less than two turns. Lifting mechanisms for lifting hot metal or flammable, explosive, toxic dangerous goods shall be provided with 2 sets of ascending position limiters, and 2 sets of limiters shall be operated in sequence, and different structures and controls shall be used for the site.
The lower limiter can be placed only on cranes where the operator cannot manage the drop and other special requirements well. The position limiter is available in both heavy and spiral versions. The type of lifting using heavy hammer and lowering limiter is composed of a limit switch and a heavy hammer. The weight is used to make the limit switch work. When the picking device is raised to a certain position, the weight is lifted, resulting in a limit in the lifting. When the contact is opened and the main power supply is cut off, the mechanism stops running and the hook stops rising as well. The moving circuit is still turned on, so that the weight can be lowered. The height limiter in spiral lifting has two forms of screw and worm drive. The screw type is composed of a screw, a slider, limit switch and the like. When the lifting device is raised to the upper position, the slider hits the limit switch, and cuts off the circuit, and controls the lifting height. When the limit switch is installed at both ends of the screw, the position of the ascent or descent can be limited.
The lifting limiter of weight is mainly used to prevent the load of the crane from exceeding the weight of the crane, so as to avoid the breaking of lifting chains and the damage of the lifting equipment. Motor overcurrent protection does not protect the crane from overload problems.
In order to prevent collisions when several cranes are placed on one track, a device for collision prevention can be installed on the crane. When the crane is operated to a dangerous range of distance, the anti-collision device issues an alarm and shuts off the circuit to stop the crane. The general alarm setting distance is between 8 and 20 meters