The operating skills of two overhead cranes for lifting the same object together

In the actual production process of an enterprise, sometimes the quality of the object to be hoisted exceeds the rated lifting capacity of the crane on site , or the object to be hoisted is too long, the crane is unstable, and the object to be hoisted is deformed. In the case of the above-mentioned situation, if the conditions permit, the method is appropriate, the on-site command is strengthened, and the safety is ensured, a plan of coordinated lifting of two cranes can be adopted. The method of operation is: when two cranes coordinate to lift the same object, the most basic condition that the sum of the rated lifting weight of the two cranes must be greater than the mass of the object to be lifted must first be met. If the lifting method of balance beam is used during lifting, the requirements are as follows:

• G object+G beam≤Ql+Q2
• Where G is the mass of the suspended object, t
• G beam-the mass of the balance beam, t
• Q1 and Q2: respectively are the rated lifting capacity of two cranes, t.

The balance beam is the load-bearing member that reasonably allocates the quality of the objects to be lifted to the two cranes. Therefore, it must meet the strength and rigidity conditions to ensure the safety and reliability of the lifting work.

1.  Under the leadership of relevant departments, relevant personnel of equipment, production and safety technology must participate in jointly formulating lifting plans and lifting techniques.
2.  After the hoisting technology is determined, the contact signal and hand style between the crane driver and the ground command must be unified . The entire lifting operation must be directed by a dedicated person. The division of labor of various operators shall be clear and each shall bear its own responsibilities, and safety inspection supervisors shall be assigned to conduct on-site safety inspections.
3.  In addition to the comprehensive and careful inspection of the mechanical, electrical and metal structures of the two cranes, special inspections of the hooks, wire ropes and brakes of the hoisting mechanism should be carried out. Defective machines and tools must not be used.
4.  Before the two cranes are officially hoisted, the balance beam should be lifted for a coordinated test run, that is, the same mechanism of the two cranes should be started at the same time, the difference in the working speed of the two cranes should be measured, and the respective working gears should be determined in advance. Achieve the same speed or close to the same speed for two cranes; if the working speeds of the two cranes differ greatly, the intermittent work coordination plan can be determined in advance to prevent accidents caused by uncoordinated movements during formal lifting.
5.  Before the formal lifting, the drivers of the two cranes should start the lifting mechanism at the same time to lift at a slow speed. When the object to be lifted is about 200 mm off the ground, then lower and brake to check the reliability of the lifting mechanism's brakes. , After confirming that there is no problem, the hoist can be formally lifted.
6.  During the hoisting process of the two cranes, only the same mechanism is allowed to be activated at the same time. Two mechanisms are not allowed to be activated at the same time to prevent accidents caused by imbalance of movement, and they must work at the slowest gear speed of each mechanism. Adjust the unequal speed difference of the two corresponding mechanisms. It is strictly forbidden to start suddenly and drive quickly.
7.  In order to ensure that the two cranes can work in coordination, the crane driver should always pay attention to the balance of the object being lifted during the operation, always pay attention to the signal sent by the ground commander, and always adjust the working speed of the mechanism to ensure the balance beam Or the object being lifted always maintains a horizontal balance. This is the key to the safety of lifting work.
8.  When starting and braking the various mechanisms of the two cranes, strive for stability and do not allow sudden starting and braking to eliminate the impact of excessive inertia force on the crane caused by the excessively short acceleration time.

If two cranes share the same object, it is best to be operated by a veteran driver with rich operating experience to prevent unexpected situations.

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