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The Main Content of The Overhead Crane Test

1.1 Visual inspection should include compliance with the specification and condition of all important parts.

Such as: agencies, electrical equipment, safety devices, brakes, controls, lighting and signalling systems.

Overhead Crane metal structures and their connectors, ladders, passages, cabs and walkways;

All guards;

Hooks or other retrieval devices and their attachments;

Wire rope and its fixing parts;

Pulley blocks and axial fasteners.

During inspection, it is not necessary to disassemble any parts, but covers that should be opened during normal maintenance and inspection, such as limit switch covers, should be opened.

Visual inspection should also include checking that the necessary certificates are provided and reviewed.

1.2 No-load test

1.2.1 Before the test, use a 500V megohmmeter to measure the main circuit and control circuit of each mechanism, and the insulation resistance to ground is not less than 1 megohm.

1.2.2 Turn on the power supply, start each mechanism, make the trolley run back and forth along the full length of the main girder and the overhead crane along the appropriate length of the track no less than 3 times, there should be no jamming phenomenon, check whether the limit switch and buffer work normally, the control system and safety Whether the device meets the requirements and is sensitive and accurate, check whether the lifting range meets the requirements.

1.2.3 During the idling test, start each mechanism separately, run in forward and reverse directions, the cumulative time is not less than 5min, and make a record.

1.3 Static load test

Purpose: Check the structural bearing capacity of the overhead crane and its components.

The static load test of each hoisting mechanism should be carried out separately, the static load test load is 1.25Gn, and the brake should be adjusted before the test.

First, do a static load test on the main hoisting mechanism. Lift the rated load (gradually increase the rated load), run the trolley back and forth across the full length of the bridge, and start the crane operating mechanism (3 mechanisms are not allowed to be started at the same time), and check that the performance should meet the design requirements. Unload the load, park the unloaded trolley to the limit position, and determine the detection reference point.

The main hoisting mechanism is placed in the most unfavorable position of the main beam, firstly loaded at 1.0Gn, suspended at a distance of 100mm~200mm from the ground, and then loaded to 1.25Gn without impact, and the suspension time is not less than 10min. Unload the load and park the unloaded trolley to the limit position, check that there should be no permanent deformation at the reference point of the main beam of the crane, and the upper camber of the main beam meets the standard requirements, then the test can be terminated. If there is permanent deformation, it is necessary to do the test from scratch, but no more than three times in total, there should be no more permanent deformation.

After the test, visually inspect for permanent deformation, peeling paint, or damage affecting the performance and safety of the crane, and inspect the joints for movement or damage.

The overloaded portion of the test shall be loaded without impact. For the overloaded part of the static load test of the hook crane, an additional water tank should be used, and water should be injected into the tank to achieve non-impact loading.

1.4 Rated load test

The purpose is to further test the relevant functional indicators of the crane through the rated load test.

The main hoisting mechanism is loaded according to 1.0Gn, which is used for the joint action of the crane, the trolley running mechanism and the hoisting mechanism. Only two mechanisms are allowed to be activated at the same time (the main and auxiliary mechanisms cannot be activated at the same time).

The static stiffness of the crane is checked by contract. Now put the unloaded trolley at the limit position, find the reference point in the middle of the main beam span, place the main hoisting mechanism of the trolley in the most unfavorable position of the main beam, load it according to the rated lifting capacity, and hang the load 100mm~200mm above the ground, keep it in the air. 10 minutes. After measuring the deflection value of the main beam, unload it, and divide the deflection value of the main beam by the span of the crane, which is the static stiffness of the crane.

1.5 Dynamic load test

Purpose: Verify the functions of the crane mechanisms and brakes.

The dynamic load test of each mechanism of the crane should be carried out separately first, and then the joint action test should be carried out. For the joint action test, no more than two mechanisms should be activated at the same time.

The hoisting mechanism is loaded according to 1.1Gn. During the test, the starting and braking of each action should be repeated within the range of its stroke. When the suspended test load is started in the air, the test load should not act in the opposite direction. During the test, the intermittent time of operation should be reserved according to the continuity rate of the electric motor of the machine, and the control should be carried out according to the operating procedures, and attention must be paid to limit the acceleration, deceleration and speed within the range of the normal middle seat of the crane. According to the power-on duration rate and its working cycle, the test time should last at least 1h.

After the test, visually check whether the components of each mechanism or structure are damaged, and check whether the joints are loose or damaged.

Note: When the crane does the static load test, it should be able to bear the test load of 1.25 times the rated lifting capacity, and its main beam should not be permanently deformed.

After the static load test of the main beam, when the no-load trolley is at the limit position, the highest point of the upper camber should be within the range of S/10 in the middle of the span, and the minimum should not be less than 0.7*S/1000. After the test, a visual inspection shall be carried out to show that there shall be no cracks, permanent deformation, peeling paint or damage affecting the performance and safety of the crane, and there shall be no looseness or damage in the joints.



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