Lifting machinery refers to equipment widely used in modern industrial production for lifting, transporting, unloading, installation, and personnel transport operations. These machines are indispensable for various industrial tasks. A grúais a type of lifting machinery that operates intermittently or repetitively. It lifts or lowers materials using a hook or other lifting devices and can also move materials horizontally.
Classification of Lifting Machinery
Lifting machinery can be categorized in several ways based on structure, function, and application. These include overheadgrúas, gantry cranes, jibgrúas, tower cranes, crawler cranes, and truck-mounted cranes. The classification typically depends on their lifting capacity, operational environment, and the specific requirements of the construction or industrial task they are designed for.
Main Parameters of Lifting Machinery
The main parameters that define the performance and capabilities of lifting machinery include:
Rated lifting capacity (Gn): The maximum weight the crane can lift.
Span (S): The horizontal distance between the center of the crane and the load.
Amplitude (L): The horizontal distance the lifting device can reach.
Lifting height (H): The maximum height the crane can lift a load.
Travel speed (V): The speed at which the crane moves, either along a track or in the air.
Lifting moment (M): A measure of the crane’s stability and lifting force.
Track gauge (k): The distance between the crane’s wheels or tracks.
Base width (B): The overall width of the crane’s base for stability.
Wheel load (p): The load on each of the crane’s wheels during operation.
Work classification: Defines the intensity and operational cycle of the crane.
Construction Standards and Terminology for Lifting Machinery
Steel Structure Components: The key components include the main beam, end beam (cross beam), trolley frame, support legs, lower crossbeam, lifting arm, balance arm, columns, gantry, struts, tower body, walkway, and operator’s cabin.
Transmission Mechanisms: These include the lifting mechanism, running mechanism, mecanismo de giro, boom adjustment mechanism, and jacking mechanism.
Electrical System: Components of the electrical system include handheld controllers, master controllers, conductive devices, cable reels, resistors, frequency converters, and control cabinets.
Main Components: These include the lifting hook, grab bucket, electric lifting magnet, steel cables, chain rings, pulleys, winches, brakes, wheels, and tracks.
Safety Devices for Cranes
Crane safety is critical, and various safety devices are installed to ensure safe operation. These include:
Height limit switches: Prevent over-lifting and ensure the load does not exceed the designated height.
End-of-travel limit switches: Stop the crane when it reaches the end of its travel to prevent accidents.
Buffer devices: Reduce the impact and shock when the crane reaches the end of its range.
Anchor devices: Secure the crane during operation to prevent movement or tipping.
Track clamps or anti-wind shoes: Ensure the crane stays on track during windy conditions.
Safety hooks: Prevent the load from accidentally falling.
Anti-tilt devices: Protect the crane from tilting over during lifting operations.
Load limiters: Prevent lifting beyond the crane’s rated capacity.
Torque limiters: Prevent overloading the crane’s structure.
Anti-collision systems: Help prevent collisions with other machinery or structures.
II. Working Characteristics and Potential Dangers of Lifting Machinery
Complex Structure and Multiple Movements
Lifting machinery typically has a large and complex structure with multiple mechanical components working in unison. During operation, the crane often moves in several directions simultaneously, making it a challenging machine to operate. The interplay between various mechanisms—such as lifting, traveling, slewing, and boom movement—requires careful coordination and skilled operators.
Handling Varied Loads
Lifting machinery is designed to handle a wide range of loads, which can vary greatly in terms of weight, size, and shape. Some loads can weigh up to hundreds of tons, while others may be large and irregularly shaped. Además, lifting machinery may be used to lift hazardous materials, such as granular substances, molten materials, or flammable and explosive items. These factors make the lifting process more complicated and dangerous, requiring operators to carefully consider the load’s characteristics and any potential risks.
Wide Operating Range
Lifting machinery often operates over a large area, requiring considerable space to maneuver. The larger the operating range, the more potential for accidents. If an accident does occur, the consequences can be significant, impacting a wide area and potentially causing damage to other structures, machinery, and personnel.
Personnel Transport
Certain types of lifting machinery, such as construction elevators, are designed to transport personnel as part of their operations. The reliability and safety of these machines directly impact the safety of the workers using them. If the equipment malfunctions or is poorly maintained, it could lead to accidents that endanger the lives of those on board. Therefore, the design, inspección, and maintenance of such equipment are crucial to ensuring the safety of personnel.
III. Potential Hazards and Safety Measures
Lifting machinery, like any heavy equipment, poses certain inherent risks. The dangers primarily stem from the high forces involved, the heavy loads being lifted, and the complex movements that take place during operation. These include:
Structural Failure: If any part of the crane’s structure—such as the boom, the frame, or the hoisting mechanism—fails, it could result in the crane collapsing or the load falling, causing injury or death. To mitigate this risk, regular inspections, maintenance, and adherence to safety guidelines are essential.
Overloading: Exceeding the crane’s rated lifting capacity can lead to mechanical failure, tipping, or loss of control. Modern cranes are equipped with load limiters that prevent lifting beyond safe limits, but operators must remain vigilant and adhere to load charts.
Wind Conditions: Cranes are vulnerable to wind, especially when lifting large or heavy loads at height. High winds can destabilize the crane and increase the risk of accidents. Many cranes are equipped with wind speed detectors that shut down operation if wind speeds exceed a certain threshold.
Swinging Loads: Swinging loads pose a risk, as they can shift unexpectedly and hit nearby structures, machinery, or personnel. Using proper rigging techniques, maintaining appropriate lifting speeds, and securing the load before lifting can help minimize this hazard.
Operator Error: Human error remains one of the leading causes of crane accidents. Misjudgments, failure to follow safety protocols, or lack of training can result in serious accidents. Rigorous training and clear communication are necessary to reduce the likelihood of operator errors.
Proximity to Power Lines: Cranes working near power lines must take extra precautions, as the risk of electrical shock is significant. Crane operators should maintain a safe distance from power lines and use insulated equipment when necessary.
Poor Ground Conditions: Uneven, soft, or unstable ground can cause the crane to tip over. Proper ground preparation, such as leveling the work area and ensuring it is firm enough to support the crane’s weight, is essential.
En conclusión, while lifting machinery plays a crucial role in industrial and construction tasks, it also comes with significant risks. Proper training, regular maintenance, and adherence to safety protocols are critical to ensuring the safe operation of these machines. Understanding the working characteristics, safety mechanisms, and potential hazards of lifting machinery is essential for anyone involved in construction or industrial operations.
