256HC Mast Section Common accident causes and preventive measures in daily use of tower crane
1. Cause analysis
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① As the spline of the output shaft of the lifting mechanism and the spline of the lifting drum are seriously worn beyond the limit, the teeth of the spiral bevel gear pair on the shaft of the lifting motor and the first stage transmission shaft of the gearbox are broken, causing the lifting mechanism out of control, causing the lifting object falling from a high place and personal injury.
② In the system controlled by electromagnetic clutch, the electromagnetic clutch is burnt out or the brush is worn too much to contact and power on, resulting in similar neutral during the shift process, and the hook is out of control and falls to hurt people.
③ The main steel wire rope or the auxiliary tools for lifting hook and sling are not replaced in time after being excessively worn in use, and they are broken in the process of lifting heavy objects, resulting in sudden weight loss and overturning of tower crane.
④ During the use of the tower body, due to the loose and falling off of the connecting bolts of the standard diagonal member, the diagonal member loses its supporting function, which leads to the damage of the diagonal member and the tower body loses its stability and overturns.
⑤ The lifting moment limiter and the weight limiter carry out lifting test or inspection within the specified range, resulting in internal contact oxidation failure due to long-term rainwater corrosion, and failure to work when the lifting is overloaded, resulting in accidents.
2. Preventive measures
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① Strengthen the regular inspection. The method: a group of experienced repairmen and excellent electricians will be formed. First, fix the main steel wire rope on the tower body with rope clamps, so that the steel wire rope will be "loose". Then, rotate the roller to judge the gear wear and clearance. If necessary, disassemble the reducer for inspection.
② After the breakpoint, remove the brush on the electromagnetic clutch, and observe whether the wear is excessive and whether the internal spring has the expansion force. If not, the center must be replaced. Use a multimeter to measure whether the clutch coil is within the specified resistance value, and then carefully observe whether the suction piece is burnt out, whether the magnetic field is generated when the coil works, and check whether the clamp spring of the valley suction piece is effective. It shall be put into use after it is confirmed to be normal.
③ Carefully check the steel wire rope, unloading clamp, hook, sling, etc., strictly implement the wear regulations of the steel wire rope, and immediately replace the broken strand, damaged fiber core or steel core, which causes significant reduction of the rope diameter, cage distortion, serious kink and other problems, so as to prevent accidents.
④ Regularly check and fasten the connecting bolts of standard section with special spanner.
⑤ Test each limiter regularly, and operate after debugging and confirming sensitivity.
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