Blog

Overhead cranes, new or old installed, must be tested and certificated qualified, and get the acceptance inspection, before being put into work. Crane inspection and crane testing are necessary and important for crane commissioning and crane acceptance, which is indispensable procedure to check the overhead crane manufacturing and installation quality, and guarantee crane safety during operation.

Overhead crane commissiong

Besides crane commissioning and acceptance inspection, the regular overhead crane inspection and loading test are required each and every year. However, in the following, the crane test and crane inspection for overhead crane commission and acceptance will be put in length.

Crane Inspection before Commissioning

For a newly installed overhead crane or overhauled crane, before commissioning, we should organize experienced electrician, fitter, crane operators and relevant technical personnel to check the overhead crane comprehensively. The crane inspection main contents are as follows:

1) Cut off the power supply of the overhead crane before inspection. According to the crane drawings and technical requirements, check and ensure:　

• all fasteners are firm;
• safety equipment and devices are installed completely;
• the overhead crane metal structure are in good condition with no deformation;
• wire rope on the pulley and drum is fixed correctly and reliably.

2) Check and make sure all rotating device is installed correctly and is able to rotate correctly and flexibly. Turn the wheel by hand and observe the moving of the output shaft and the revolving of the driven organization, making sure all are in stable rotation, with no block or stuck.

3) Overhead crane brake should be accurate and reliable. Two brakes should be consistent with each other, which are installed for the running mechanism of overhead crane.
4) All lubricating points should be lubricated with the required lubricating oil according to the rules and oil amount on reducer shall be within the prescribed scope.
5) Electrical equipment inspection

• Check the insulation resistance of the circuit system with a megohmmeter.
• Make sure all electrical equipment are comply with the provisions.
• In the case of a disconnect power circuit, if operating line is correct, the controller is flexible and reliable
• The electrical equipment should work normally, especially pay attention to the electromagnet, limit switch, and emergency switch.

Crane Test Preparation before Commissioning

• Clean up overhead crane test site and make sure the irrelevant personnel can’t come in.
• Prepare a testing object being 1.25times of rated capacity of the overhead crane. It is better to weigh it in advance.
• Lifting steel wire rope or belt.
• Tools to examine bending, such as steel line(Jean line), plumb and measuring tool.
• Testing staff should include equipment manager, engineer, technician and operator.
• Test personnel should know commissioning aims, requirements and methods, and the necessary division of labor, select experienced operator to trial operation.

Overhead Crane Commissioning

After inspection and preparation, the overhead crane operation test can proceed. The running test of overhead crane can be divided into the following three steps:　no－load test, static load test, and movement test.

 10 ton electric hoist testing 

Overhead crane no-load tests

Overhead crane no-load test are mainly divided into the three parts, the crane trolley travelling test, overhead crane travel test, and no-load hook test.

Trolley/ hoist travel test

• Start the trolley/hoist of overhead crane, and
• Make the trolley /hoist run back and forth along the rail more than 3 times
• Test limit switch to make sure is sensitive and reliable.
• The driven wheels must touch rail all the time, the space between positive wheel and rail should be not more than 1mm.

Crane travel test

• Make the overhead crane run back and forth along the rail more than 3 times. Each time running distance is 3m at least.
• Wheels of the overhead crane must not stuck rail.

No-load hook test

• Lift the empty hook up and down more than 3times.
• Examine brake and lifting limiter.
• All traveling and lifting mechanism must work stable, no vibration and shock

Overhead crane static load tests

• Before Static load testing, the no-load test must be qualified.
• Set crane on one end of rail. Trolley/hoist lifts the rated capacity and travel along the crane girder back and forth.
• Unload the loads and set the trolley to one end of the crane girder.
• Hanging a plumb in middle of crane girder to examine the original bending degree. Operating trolley/hoist come to middle of girder, lifting loads 1.25times of rated capacity, up to 100mm, and keep this condition 10min on both sides of girder.
• Then examine the bending degree again.
• Then unload the capacity, to check if girder has any permanent change. This testing should do 3times.
• Then examine the final bending degree which should be bigger than 0.8L/1000.
• Place trolley/hoist stop in middle, lifting rated capacity to test girder’s resilience downwarping, which should not be more than L/700. For single girder overhead crane, the resilience downwarping should be not more than L/600.

Movement load tests

• Lift loads of 0.5 time, 0.7 time, 1 time and 1.1 times of rated capacity of the overhead crane.
• Make trolley/hoist travel several times.
•  If no problem is observed, start crane traveling mechanism and run the overhead crane several times.
• Lifting mechanism must be operated 10-15min, traveling mechanism must work 20min or 10times.
• Ensure the brake is workable, reducer has no noise, no vibration, and temperature is normal, no oil leaking;
• Make sure the lubricating system is fine.
• Make sure all limiters and safety device are reliable.
• And electrical box is fine, temperature is normal, no noise, no vibration, cable/line connecting is not burnt.