When lifting heavy objects, the hook wire rope should remain vertical. It is not allowed to drag the lifted object diagonally.
When lifting heavy objects, the center of gravity should be accurately located and the object should be firmly bound. If there are sharp corners, they should be padded with wooden blocks.
Before the heavy object is lifted off the ground, the crane must not make a slewing motion.
When lifting or lowering heavy objects, the speed should be uniform and stable. Avoid sudden changes in speed, which may cause the heavy object to swing in the air and pose a danger. When lowering the heavy object, the speed should not be too fast to prevent the object from being damaged when it hits the ground.
When the crane is lifting a load, try to avoid raising or lowering the boom. If it is necessary to raise or lower the boom while lifting a load, the lifted weight must not exceed 50% of the specified weight.
When the crane is slewing while lifting a load, pay close attention to whether there are any obstacles around. If there are obstacles, try to avoid or remove them.
No personnel should stay under the crane boom, and try to avoid people passing through.
When two cranes are operating on the same track, the distance between them should be greater than 3 meters.
When two cranes jointly lift an object, the lifted weight must not exceed 75% of the total lifting capacity of the two cranes. The traveling, lifting, and lowering actions of the two cranes should be consistent.
The hoisting and luffing wire ropes need to be inspected once a week, and records should be made. Specific requirements shall be implemented in accordance with the relevant regulations for hoisting wire ropes.
When the crane is traveling or slewing empty, the hook should be more than 2 meters above the ground.
When the wind force exceeds force 6, work should be stopped immediately. For TMK, the boom should be turned to the downwind direction and lowered appropriately, and the hook should be firmly hung. The gantry crane must be fixed with iron wedges (rail stoppers), and the hook should be raised to the upper limit. At the same time, close the doors and windows, cut off the power supply, and fasten the guy ropes. The same measures should be taken after normal work is completed.
It is strictly prohibited to stack sundries on the crane platform to prevent them from falling and hurting people during operation. Frequently used tools should be placed in the special toolbox in the operator’s cab.
During operation, sudden speed changes or reverse driving are not allowed, as this may cause the heavy object to swing in the air. It is also not allowed to operate more than two (including the auxiliary hook) operating mechanisms simultaneously.
When starting the crane, the operator’s hand must not leave the controller. In case of a sudden failure during operation, measures should be taken to safely lower the heavy object, then cut off the power supply for repair. It is strictly prohibited to carry out maintenance during operation.
The crane must not lift in any of the following situations:
The heavy object exceeds the rated lifting capacity of the crane.
The weight of the heavy object is unknown.
The signal is unclear.
The heavy object is not firmly bound.
In outdoor operations, when encountering strong winds of force 6 (force 5 on the beam) or above, heavy rain, thick fog, and other severe weather conditions.
Poor lighting during night operations.
Oblique pulling.
The wire rope is severely worn with broken strands, or there are people repairing on the crane or in the machine room.
Gantry cranes are powerful and essential pieces of equipment in many industrial and construction scenarios. Their safe operation is of utmost importance to protect the lives of workers, the integrity of the goods being lifted, and the longevity of the crane itself. Let’s expand on each safety point in more detail.
For the first rule about keeping the wire rope vertical, this is based on the principle of force distribution. A diagonal pull subjects the rope to uneven stress, increasing the risk of premature wear and sudden breakage. It also makes the lifted object unstable, potentially leading to collisions with surrounding structures. When it comes to finding the center of gravity and proper bundling, this is a science in itself. Engineers and operators need to consider the shape, density distribution, and size of the object. In complex objects like large machinery parts with irregular shapes, special rigging techniques and calculations are often required to ensure the load is balanced.
The restriction on slewing before the load is off the ground is a preventive measure against tipping. When a crane starts to rotate while the load still has contact with the ground, the uneven friction and lateral forces can cause the crane’s base to shift, endangering the entire structure. Maintaining a uniform speed during lifting and lowering is crucial for the same reason of stability. A sudden acceleration or deceleration can generate inertial forces that make the load swing uncontrollably, and in a crowded work area, this could lead to disastrous consequences.
The limitation on boom movement while under load is due to the significant change in the crane’s center of gravity. When the boom is adjusted, the distribution of weight between the front and rear of the crane changes. If the load is too heavy during this adjustment, the crane may become unbalanced and tip over. The need to be cautious during slewing with a load, especially regarding obstacles, cannot be overstated. In a busy port or construction site, there are often numerous fixed structures, vehicles, and workers in the vicinity. A collision during slewing could damage the crane, the load, and endanger lives.
The rule about keeping people away from the boom area is simple yet vital. The boom is a moving part, and in case of any mechanical failure or unexpected movement, anyone underneath would be at high risk of being crushed. The requirement for a safe distance between two cranes on the same track is to prevent collisions. In a long line of gantry cranes working in a container terminal, for example, if the distance is too short, a small misjudgment in movement could result in a costly and dangerous impact.
When two cranes work together, the 75% limit on the combined load is set to account for the potential differences in synchronization and the additional stress on the cranes’ structures. Even a slight delay or uneven force distribution between the two cranes can cause excessive strain. Regular inspection of the wire ropes, as stated in point 10, is a fundamental part of maintenance. These ropes are the lifelines of the crane, and any unnoticed wear or damage could lead to a catastrophic failure.
The height requirement for the hook during empty travel is to avoid accidentally hitting any low-lying obstacles or personnel. In a busy warehouse, there may be stacked goods, forklifts, or workers scurrying around, and keeping the hook elevated reduces risks. The wind force limit is another critical factor. High winds can exert huge lateral forces on the crane, making it unstable. The specific procedures for battening down the crane in windy conditions, like turning the boom and securing it, are designed to minimize wind resistance and prevent tipping.
The ban on storing items on the crane platform is a common-sense safety measure. Loose items can easily roll off during the crane’s movement, potentially hitting workers below. The restrictions on operation speed changes and multiple mechanism operation are to maintain the crane’s stability. Sudden movements can disrupt the carefully balanced forces within the crane, while operating too many functions simultaneously can overload the control systems.
During operation, the operator must always be in control. If a fault occurs, safely lowering the load first is essential because an uncontrolled load in mid-air is a massive hazard. The list of situations where lifting is prohibited covers all the major risk factors. Lifting an overweight object is an obvious no-go, but the other conditions like unclear signals, poor lighting, and bad weather also greatly increase the chances of accidents, from miscommunication to the crane being buffeted by the elements. Each of these safety precautions forms a crucial part of a comprehensive safety net for gantry crane operations, and continuous training and strict enforcement are needed to ensure compliance.
