Rail Mounted Gantry Crane, also known as RMG, is a kind of heavy equipment used for efficient handling and loading/unloading of containers, which is widely used in port container terminals, railroad freight yards, and so on. In this article, we will provide you with a professional rail mounted gantry crane maintenance guide, including daily inspection, regular maintenance, fault diagnosis and safe operation, and other maintenance strategies and standardized operating procedures, to help your business reduce unexpected downtime and repair costs.
The Importance of Maintenance for Rail Mounted Gantry Cranes
Regular maintenance can significantly reduce the equipment failure rate.
Good maintenance status can extend the service life of the equipment.
Standardized maintenance operations can effectively prevent safety accidents.
Inspection and Maintenance of Rail Mounted Gantry Crane
The rail mounted gantry crane consists of bridge structure, hoisting mechanism, running mechanism, electrical system, rail system and other components. Inspection and maintenance of the main components can ensure the safe and stable operation of the crane. Please check out the article on the structural composition of the rail mounted container gantry crane parts.
Gantry frame
Lifting trolley
Trolley operating mechanism
Mobile drivers cab
Crane power supply and trolley feed mode
Electrical protection
Platform&ladder
Container Spreader
Metal structure system: including the main beam, outriggers, end beams, and other load-bearing parts, which need to be regularly inspected for weld seams, bolt connections, and corrosion.
Hoisting mechanism: This key part of maintenance consists of a motor, reducer, reel, wire rope, and spreader. The wire rope should be checked regularly for end fixation and replaced immediately when its diameter becomes thinner than the standard or when the wire is broken.
Running mechanism: including the big car and trolley traveling system, need to pay special attention to the wheels and the track with the state." Gnawing" phenomenon (wheel rims seriously touching the rails) will lead to abnormal noise and vibration, and should be adjusted in time to the lateral inclination of the wheels or check the synchronization of motors and brakes.
Electrical system: This covers power supply, control, and protection devices. Maintenance points include checking cable insulation, contactor contacts, and safety limit switches. The electrical system should have multiple safety functions, such as short-circuit and overload protection, loss of voltage protection, zero protection, and emergency power-off protection.
Rail system: As the basis of crane operation, the rail needs to maintain flatness and gauge accuracy. The rail side wear should be replaced when it exceeds 15% of the original size, and the height difference at the rail butt should not be more than 1mm.
Maintenance cycle reference for main components of rail mounted gantry cranes
The comprehensive inspection and maintenance system of rail-mounted gantry cranes includes daily inspections, monthly inspections and annual comprehensive overhauls to ensure that the equipment is always in the best working condition.
Components/Systems
Daily Inspection
Monthly maintenance
Annual Overhaul
Bridge Metal Structures
The presence of obstructions, oil or snow, or ice; Check that track pressure plates and bolts are tight;
Repair welds, tighten bolts
Full inspection and evaluation
Wire Ropes
The presence of obstructions, oil or snow, or ice; Check that track pressure plates and bolts are tight.
Lubrication maintenance
Replacement
Brakes
Check for broken wires, flattening, kinking, or abnormal wear.
Test the braking performance of the hoisting and traveling brakes under no-load conditions.
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Electrical Systems
Function test
Clean and tighten contacts
Insulation testing, drying treatment or component replacement
Rails
Check for deformation, cracks, loose bolts on the main beam, outriggers, end beams, and other components
Measurement of gauge and leveling
Overall adjustments
Daily Inspection
The daily inspection and regular maintenance system for rail mounted gantry crane maintenance is the key to preventing equipment failure and prolonging service life. Take 15-30 minutes to quickly complete the inspection before daily operations. Daily inspections should be performed by trained operators, and a standardized inspection record sheet should be filled out. The main inspections include:
Metal Structure Inspection: check whether the main beam, outriggers, and other main stress components have obvious deformation, cracks, or paint peeling. Pay special attention to the main girder and outrigger joints, rail butt joints, etc.
Wire rope system: check whether the wire rope has broken wire, flattened, twisted, or abnormal wear. At the same time, check whether the rope end fixing device is firm and whether the wedge and pressure plate are loose.
Brake function test: test the braking performance of the hoisting and traveling brakes under no-load conditions. For the hoisting mechanism, the brake must be able to effectively stop the load of 1.25 times the rated lifting capacity.
Verification of safety devices: Test one by one whether the functions of all kinds of limit switches (upper limit of lifting, traveling limit, etc.), overload protection devices, and emergency stop buttons are normal. An overload limiter in the load to reach 90% of the rated lifting capacity should issue a prompt alarm signal, more than exceeds the rated lifting capacity should be able to automatically cut off the lifting power source.
Track status check: Before walking to see if there are any obstacles, oil or snow on the track; check the track pressure plate, bolts are tight; observe the track joints at the gap is normal (generally 4-6mm). The height difference at the rail butt joints should not be more than 1mm, and the lateral misalignment should not be more than 1mm3.
Monthly Maintenance Inspection Contents
Monthly maintenance of rail mounted gantry cranes should be more comprehensive and in-depth, which usually takes 2-4 hours to complete, and it is recommended to be carried out by professional maintenance personnel. In addition to including all items of the daily inspection, the monthly maintenance should also include the following:
Lubrication System Maintenance: Clean and fill all lubrication points with appropriate grease according to the lubrication chart provided by the equipment manufacturer. Pay special attention to critical areas such as bearing housings, gear couplings, and pulley bearings. Before lubricating the wire rope, the surface dirt should be removed with kerosene, and then the special grease heated to above 80℃ should be evenly applied.
Electrical system check: Open the electrical cabinet to check whether the contactor contacts are ablated and whether the line connection is loose; measure the insulation resistance (it should not be lower than 1MΩ); clean the sliding contact surface of the collector; and check whether the cable reel is working normally. The power supply cable should keep the surface clean, the insulator intact, and firmly fixed on the support beam.
Structural connection check: Use a torque wrench to check the tightening torque of the main structural connection bolts, especially the high-strength bolts connecting the main beam to the outriggers. Also, check whether there are visible cracks in the welds, especially in the parts subject to alternating stress.
Traveling mechanism adjustment: check the wheel tread wear (should not exceed 15% of the original thickness); measure and adjust the wheel's horizontal deflection and vertical deflection (generally not more than 1/1000); check the “gnawing rail” phenomenon. If found gnawing rail, should re-adjust the wheel lateral inclination, so that the two active wheels (or driven wheels) inclination angle is opposite.
Comprehensive Inspection and Maintenance for Annual Overhauls
Annual overhauls are the most comprehensive and in-depth, usually requiring 3-7 days of downtime, and are completed by a professional team using specialized equipment. The annual overhaul not only includes all the elements of routine and monthly maintenance, but also the following specialized inspections and maintenance:
Non-destructive testing of metal structures: Use ultrasonic flaw detectors to inspect major stress welds and stress concentration areas to detect internal defects. Suspected cracks found should be eliminated and rewelded with a good welding rod.
Comprehensive inspection of track system: Use a laser range finder and precision level meter to measure the straightness, levelness, and gauge accuracy of the track. The deviation of straightness of rail should not be more than 5mm/10m, and the height difference between the top surfaces of two rails of the same cross-section should not be more than 10mm; for the rail section with serious wear, the side wear should be replaced if it is more than 15% of the original size.
Comprehensive test of electrical system: including insulation test of motor winding (not less than 1MΩ), function verification of protection device, and response time measurement of control system. Check the tightness of all terminals and replace aged or broken cables. The protection level of the control cabinet and terminal box should reach IP55 to prevent dust and moisture intrusion.
Hydraulic system maintenance: For cranes equipped with hydraulic rail clamps (such as those used in some modernized girder yards), hydraulic oil cleanliness, cylinder sealing, and solenoid valve working status should be checked.8 Hydraulic rail clamps have the advantages of large clamping force, fast response, and automatic interlocking compared with traditional manual rail clamps, which can effectively prevent gantry cranes from tipping over in strong winds.
Anti-corrosion treatment and painting: after thorough cleaning of the metal structure, check the paint condition and make necessary repairs. According to the standard, the surface of the main components of the steel structure should be shot blasted to reach Sa2.5 level, and the painting system includes epoxy zinc-rich primer, epoxy rust preventive primer, and top coat, which is required to be even, detailed, bright, and consistent in color.
By establishing a daily-monthly-annual comprehensive and systematic maintenance system for rail mounted gantry cranes, it can effectively reduce the equipment failure rate, extend the service life of the equipment, and at the same time improve the operational safety and productivity. Note that the above maintenance records should be kept completely and analyzed regularly to provide data support for optimizing the maintenance strategy.
Conclusion
By establishing daily-monthly-annual systematic troubleshooting and emergency response measures, the maintenance of rail mounted gantry cranes can minimize unplanned downtime, safeguard the safety of personnel and equipment, and at the same time extend the service life of the crane. Maintenance personnel should regularly conduct emergency drills to familiarize themselves with the process of handling various faults to ensure that they can act quickly and correctly in an emergency. Note that all the above maintenance records should be kept completely and analyzed regularly to provide data support for optimizing the maintenance strategy.
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