Gantry Cranes

Single girder gantry crane specifications

Double girder gantry crane specifications

Gantry cranes are widely used to lift and move heavy objects in freight yards of mechanical processing plants, metallurgical plants, chemical plants, nuclear power plants, shipyards, ports and docks.

The most common difference between the two is that for gantry cranes, the entire structure is directly mounted on the ground track, with legs and running mechanism connected under the main beam. While the overhead crane is installed on the elevated runway beams, which can make full use of the space under the crane.

Wanna know similarities and differences between gantry cranes and bridge cranes in specifications, structures, working environments, visit gantry crane vs. bridge crane.

If installed, maintained and used properly, the gantry crane is very easy and safe to use. The crane has many safety device options to ensure safe operation:

• Overload limiter
• Lifting limit switch
• Travel limit switch
• Deflection adjustment and display device
• Interlock protection device
• Buffer
• Rail clamp
• Anti-tip safety hook
• Rail end stop
• Rain cover for electrical equipment

The maximum load capacity of gantry cranes can reach up to 500 tons, the maximum span up to 35m, and the lifting height up to 18m.

Hook

• The design and manufacture of hooks are in compliance with the GB/T 10051-1988 standard.
• The hook is a forged single hook, which is forged by DG20.
• All hooks are equipped with hook closures to preventthe lifted loads from being unhooked.
• The ratio of the diameter of the pulley to the diameter of the wire rope is greater than 20 to ensure the service life of the wire rope.
• The pulleys are equipped with protective covers or devices to prevent the wire rope from jumping out of the groove.

Coupling And Drive Shaft

• Using safe and reliable drum-shaped gear coupling to connect the transmission components of each mechanism, transmitting torque and compensating for the angular and radial deviation caused by a certain installation error at the same time, improving the dynamic characteristics of the transmission device.
• The transmission shaft is made of 45# steel, and the strength calculation is strictly carried out to ensure itsstrength and stable torque transmission.

Drum Group

The drum device is mainly composed of drum gear ring, drum, intermediate shaft device, bearing base and limit guide rod device. Rope grooves are machined on the drum to make the wire ropes orderly arranged.

Wire Rope

The wire rope complies with the regulations in GB 8918-2006 “Wire Ropes for Important Uses”.

Wheel Set

• The choice of wheel diameter and material is based on the maximum supporting force of the wheel under the most unfavourable conditions to ensure thatthe wheels will not be overloaded.
• The wheel material adopts ZG340-640, and undergoes advanced power frequency heat treatment and quenching.
• There must be no defectson the wheel tread and the inner surface of the wheel flange, and no welding repair is allowed.

Electric Motor

• The insulation class of the motor is F, and the protection class is IP54/IP55.
• The motor has the characteristics of reasonable structure, reliable performance, high quality, large overload capacity and high mechanical strength.

Reducer

The reducer is a special reducer for cranes, which has high carrying capacity, high efficiency, low noise and low vibration.

Brake

The brake adopts YWZ series electro-hydraulic block brake, which is stable, safe and reliable.

Metal Structure Pretreatment and Coating

• The steel material of the crane metal structure is often Q235B or Q345B carbon structural steel.
• The steel used for crane metal structure should be subjected to surface shot blasting and rust removal.
• The main welding method is automatic submerged arc welding, and the others are carbon dioxide gas shielded welding and AC welding.The main butt welds of structural parts must be 100% non-destructive inspection.
• The surface of the crane should be painted before leaving the factory, and anti-rust measures should be taken for the exposed surface that is not painted. The primer used by our company is epoxy zinc-rich primer with strong corrosion resistance, stability and good adhesion, and the topcoat is a chlorinated glue topcoat with high corrosion resistance and strong adhesion. After painting, the crane has good gloss and beautiful appearance, which can greatly extend the service life of the equipment.

Gantry cranes generally have three mechanisms: lifting mechanism, trolley running mechanism and crane running mechanism. Its working principle is as follows:

1. In normal working procedures, first start the lifting mechanism for lifting action, the empty hook descends, and hoists the load to a certain height, and then start the trolley running mechanism and the crane running mechanism to the designated position.
2. Start the lifting mechanism again to lower the items, and then the empty hook rises to a certain height, and the trolley runningmechanism and the crane running mechanism crane return to their original positions to prepare for the second hoisting work.
3. Every time an item is hoisted, the above process is This process is usually called a cycle.In a cycle, the mechanisms do not work at the same time.

• GB / T 14406-1993 Universal Gantry Crane
• GB / T3811-2008 Design specification
• JT400-1999 Port Gantry Crane Safety Regulations
• GB/T17495-1998 Port Gantry Cranes – Specifications
• GB / T17496-1998 Technical Code for Repairing Port Gantry Crane

Tips for gantry crane installation:

• Laying a cart rail (usually by the demand side ), but before installing the mobile gantry crane must be re-testing of the track, gauge error cannot exceed 10 mm.
• Crane cart installation, to ensure the carts on both sides of the parallelism, verticality, you can pull line, pull the diagonal, all antonyms and other means to carry out correction.
• Lifting the splicing good legs, connecting it with the cart, and the wind cable tension, the general one leg 4 cables, after loosening the hook (cable fixed legs will not dump down.
• Lifting spliced good girders (girders have a piece or two, user requirements to be set) on both sides at the same time, on the erected legs.

How does the gantry crane make energy-saving emission reduction?

Gantry crane is the abbreviation of the portal crane, and energy-saving emission reduction is mainly in the crane selection and manufacturing phase, the selection of energy-saving effect of four-bar linkage gantry crane, motor selection of energy-saving motors and low resistance bearings, installation of high-efficiency frequency control system. In the operation can try to make the grab full, hook locks according to the choice of goods weight hanging crane lock. As far as possible in the production organization based on a single piece of groceries size and weight to arrange the appropriate berth and door machine operations.

What problems should pay attention to about the gantry cranes lubrication?

Lubrication did in order to ensure the normal operation of various parts of the crane and can extend the service life of the crane, at the same time, lubrication will affect the production efficiency and so on. Lubrication is a very important part of the crane’s routine maintenance. The crane lubrication is very important.
The material of lubrication must be clean, and lubricants of different brands cannot be mixed. In addition, the choice of lubricants above should be appropriate, according to the rules of regular lubrication. Always check the gland seal lubrication system.

In lubrication, to keep the power outage, so as to avoid accidents, of course, except for the lubrication of electric systems. Gantry crane lubrication, for moderately higher lubrication points, should increase the number of lubrication and installation of insulation or cooling device. Try to grease to the friction surface.

It also needs to pay attention to the sodium-based grease absorbent easy to failure, therefore, should not use this lubricant in wet areas.

In order to avoid unnecessary losses, the crane operator needs to pay special attention to safety issues when using lifting equipment.

For reasons of ambient safety, basic safety precautions should always be followed during installation and maintenance to prevent the risk of fire, electric shock, and personal injury. Including the following aspects:

• Never install the device in an unknown liquid pipe to prevent accidental production.
• Never install the power cord during a lightning storm.
• Do not immerse the power supply in the water.
• In any case, all matters related to product installation, modification, and maintenance, the power must be cut off before the completion of all work in order to power back.

In circumventing the relevant safety issues outside the environment. Lifting equipment installation precautions also do the following analysis:

•  before the test should be checked in the case of cutting off all the power.
•  brake operating mechanism, the adjustment should not be too loose or too tight, in order to prevent the car phenomenon and the impact of the phenomenon is appropriate.
• Track alignment not only to track the vertical direction of the bend but also the school lateral bending because the lateral is not straight, the wheel will be stuck in the process of crane operation, so the lateral bending is the focus of alignment.
•  Platen can be used on the 3rd ordinary carbon steel, welded according to the requirements of processing.
• The joint position of two parallel rails should be staggered, and its offset distance should not be equal to the base distance of the front and rear wheels of the crane.

Learn about some of the problems you may encounter during the operation of the gantry crane and what measures you can take to avoid them.

1. Wheel Gnawing on the Track

Wheel gnawing on the track means that the rim of the wheel is in serious conflict with the track, making noise or vibration during operation.

If the wheels of the crane always gnaw the rail in one direction, the horizontal deflection of the wheels (either the two driving wheels or the passive wheels) should be adjusted.

If the rail gnawing directions are opposite during the round trip, it is likely that the two motors or brakes are not synchronized.

If the rail is gnawed on a certain stroke, there may be deviations in the track installation.

If rail is always gnawed on the stroke, there is a problem with the track span.

2. Driving Wheel Skidding

If the driving wheel is slipping, check the wheel rolling surface to see if it is on a flat surface. If not, the angle bearing box should be padded and adjusted.

If there is oil on the track, fine sand can be sprinkled on the track surface to increase the coefficient of friction.

Also, you can adjust the braking torque to prevent excessive braking.

3. Safety Switch Failures

The failure of the safety switch is mainly caused by the sticking or displacement of the internal objects of the switch.

When adjusting and using it, pay attention to the following points:

• The ascent limit safety switch should ensure that when the empty hook rises, its uppermost point is not less than 200mm away from the related objects of the trolley at the moment of power failure.
• The safety switch should be re-adjusted every time the wire rope is replaced or connected.
• The reliability of the switch should be checked every shift.

4. Issues With Electrification System

• When the mainknife switch of the power distribution protection box is closed, the fuse of the control circuit fuse is blown, indicating that there is grounding or short-circuit phenomenon in the control circuit. It should be checked step by step and eliminated.
• When the emergency switch is closed, the main contactor cannot be connected. The reasons may be that the main knife switch is not closed; the door is not closed; the controller is not in the zero position; there is no voltage on the line; the fuse of the control circuit is blown; the contactor coil is damaged.
• When operating the controller, the motor does not run. The reasons may bethat the stator circuit is open; there is no voltage on the circuit; the brake is not opened; the contactor of the contactor is in poor contact; the rotor circuit is open; the slip wire is in poor contact with the collector.
• The motor cannot deliver the rated torque and rotates slowly. The reasons may bethat the brake is not fully opened; the line voltage has dropped too much; the slip wire is in poor contact with the current collector; one phase of the stator and rotor wires is incorrectly connected.
• After the limit switch is activated, the corresponding motor is continuously energized. The reason may bethat short circuit in the limit switch circuit or wiring errors in the limit switch circuit.
• After the contactor coil is de-energized, the contactor does not release. The reasons may bethat there is a short circuit in the control circuit; the movable part is stuck; the contacts are welded.
• Issues with the contactorand relay

Coil temperature is too high or the noise is strong. The reason may be that the coil is overloaded; the spring pressure of the moving contact is too large; the working surface of the magnetic conductor is dirty; the movable part of the magnetic conductor is stuck; the screw fixing the magnet is loose.

The contact is overheated, burnt or welded. The reason may be that the spring pressure or overtravel of the moving contact is too small; the contact is dirty, the surface is uneven, and the contact is not close, so a tiny arc is generated; the energization time of the coil is less than the inherent pull-in time of the contact, so the contact is not completely closed when the power is cut off, generating an arc; the movable part is stuck.