An overhead crane, also known as a bridge crane, operates by moving along a runway system installed overhead. It typically consists of several major components, each playing a crucial role in its operation.
- Bridge: The bridge is the main structural component that spans the width of the area where the crane operates. It travels along the runway and supports the trolley and hoist.
- Runway Rails: The runway is a set of rails or tracks that the bridge travels on. It is usually mounted on the building structure and runs the length of the area covered by the crane.
- Hoist: The hoist is the lifting mechanism of the crane. It can be either electric or manual and is used to raise and lower loads.
- Trolley: The trolley travels along the bridge and supports the hoist. It allows for the movement of the hoist along the length of the bridge.
- End Trucks:The end trucks are located at either end of the bridge and contain the wheels that run along the runway. They support the bridge and facilitate its movement.
Overhead Crane Operation
Operating an overhead crane requires comprehensive training and adherence to safety protocols to prevent accidents and ensure efficient operation. Here’s a general guide on how to operate an overhead crane:
Pre-Operation Checks
- Performing a thorough visual inspection of the overhead crane before operation is crucial to ensure safety and proper functioning. Check for any signs of damage or wear on the crane structure, hoist, trolley, cables, and hooks.
- Ensure that all safety devices, including limit switches, emergency stops, and overload protection, are fully operational.
- Verify that the area around the crane is free of obstacles and personnel.
- Ensure the load to be lifted is properly secured and within the crane’s rated capacity.
Positioning
- Position the crane directly above the load to be lifted.
- Ensure that the crane hook is positioned directly over the center of gravity of the load.
Operating the Controls
- Familiarize yourself with the crane’s control panel, which typically includes buttons or levers for hoisting, lowering, trolley movement, and bridge movement.
- Use the controls to operate the crane smoothly and with precise control.
- Always use gradual movements to avoid sudden swings or jerks when operating the crane.
Lifting the Load
- Engage the hoist to lift the load slowly and steadily, ensuring a controlled ascent.
- Monitor the load closely as it is lifted to ensure it remains stable and does not swing excessively. Adjust the hoist movement as necessary to maintain control over the load throughout the lifting process.
- Avoid lifting the load too quickly or exceeding the crane’s rated capacity to ensure safe operation and prevent potential equipment damage or accidents.
Moving the Load
- Use the trolley controls to move the load horizontally to the desired location with smooth and controlled movements.
- Make sure to position the load precisely using the trolley controls, and be mindful to avoid collisions with obstacles or other equipment in the vicinity.
Lowering the Load
- Lower the load slowly and carefully using the hoist controls to maintain control and ensure a safe descent.
- Ensure that the load is lowered to the ground or its designated destination safely and without incidents.
- Avoid dropping the load or allowing it to swing during lowering to prevent accidents and ensure safe handling of the load.
Shutdown Procedure
- After completing the lift, safely return the crane to its starting position to prepare for the next operation or to park the crane.
- Lower the hook to a safe height and engage any locking mechanisms to secure the crane and prevent unintended movements.
- Shut down the crane controls and secure the crane against unauthorized use by following proper shutdown procedures and ensuring control panels are deactivated or locked.
Post-Operation Checks
- Inspect the crane and its components thoroughly for any signs of damage or issues that may have occurred during operation.
- Report any problems discovered during the inspection promptly to the maintenance team or supervisor.
Safety Precautions
- Always wear appropriate personal protective equipment, such as helmets and gloves, while operating the crane to ensure personal safety and minimize risks associated with handling heavy equipment.
- Follow all safety regulations and procedures provided by your employer or regulatory authorities to ensure safe operation of the crane and maintain a secure work environment for yourself and others.
- Never exceed the crane’s rated capacity or attempt to lift loads that are too heavy or awkwardly shaped.
- By following these steps and prioritizing safety, you can effectively and safely operate an overhead crane to lift and move loads in various industrial settings.
Protection Devices for Overhead Cranes to Ensure Safe Operation
Overhead cranes are equipped with various protection devices to ensure safe operation and prevent accidents. These devices help to protect both personnel and equipment. Here just list some safety devices for your reference.
- Overload Protection: Overload protection systems prevent the crane from lifting loads that exceed its rated capacity by utilizing load sensors or load cells. These devices monitor the weight of the load being lifted, and if the load exceeds a preset limit, the system will either prevent further lifting or alert the operator with a warning.
- Limit Switches: Limit switches are installed at various points along the crane’s travel path, such as at the ends of the runway or on the trolley, to define the maximum and minimum travel limits of the crane’s movements. When the crane reaches these limits, the limit switches automatically stop the motion of the crane to prevent collisions or overtravel.
- Emergency Stop Button: An emergency stop button enables the operator to swiftly halt all crane movements in the event of an emergency. When activated, the emergency stop button promptly disables power to the crane’s motors, ensuring an immediate and safe cessation of motion.
- Anti-Collision Systems: Anti-collision systems are implemented to prevent collisions between multiple cranes operating in the same area or between the crane and other equipment or structures. These systems utilize sensors or cameras to detect potential collisions. Upon detection, they automatically intervene by stopping or adjusting the crane’s movements to avert accidents and maintain safe operations within industrial environments.
- Warning Lights and Alarms: Warning lights and alarms provide visual and auditory warnings to alert personnel in the vicinity of the crane to potential hazards. These may include flashing lights, sirens, or audible alarms that activate when the crane is in operation or when specific conditions are detected, such as an overload or approaching a limit switch.
- Wire Rope Monitoring: Wire rope monitoring systems are employed to continuously monitor the condition of the crane’s lifting cables or ropes. These systems utilize sensors to measure parameters such as tension, elongation, or other indicators of rope health. In case abnormalities are detected, these systems provide warnings to alert operators or automatically shut down the crane to prevent unsafe conditions and potential accidents.
- Fall Arrest Systems: Fall arrest systems are used to protect personnel working at heights on or near the crane. These systems typically include harnesses, lanyards, and anchor points that prevent workers from falling in the event of a slip or other mishap.
The specific devices used will depend on factors such as the type of crane, its intended use, and local safety regulations. Regular maintenance and inspection of these devices are essential to ensure they remain functional and effective in preventing accidents.