Overhead Cranes

Since overhead cranes are highly customized products, their prices vary widely.

Generally, the cost of overhead crane is determined by several factors: type of crane, load capacity, span, lifting height, building or structural requirements, transportation cost, etc.

For example, if you own a large manufacturing plant, you may need large double girder overhead cranes to get the job done quickly and efficiently, which will cost much more than a smaller business that needs smaller overhead cranes to fit inside of a warehouse.

Overhead crane is mainly composed of bridge frame (main beam, end beam, trolley running track, etc.), hoist trolley, bridge running mechanism and electrical control system.

1. Bridge Frame:

The bridge is the main force-bearing component of the crane. The main girder and end beam are the main load-bearing parts, supplemented by trolley tracks, walking platforms, railings, ladders and other auxiliary metal structures.

Main beam – The main beam is a box-shaped structure. The main load-bearing material of the main beam is Q235-B, and the minimum plate thickness is not less than 6mm.

End beam – The end beam is a box-shaped structure, and the connection between the end beam and the main beam is a rigid connection. In order to facilitate transportation, the end beam is disconnected, which is connected by high-strength bolts at site.Trolley track – The trolley track adopts the whole track with joints welded together to ensure that the trolley runs well.

Walkway railing – The tread of the bridge platform is made of non-slip patterned steel plate with a thickness of 3mm. Railings with a height of 1050mm are set on the passages of the bridge frame.

Cabin – The driver’s cab is the working place where the operator controls the crane, and it adopts a closed, toughened glass cab. In order to ensure a wide view of the operator, tempered glass is installed on the upper front, lower front side and rear wall of the cab. An alarm is also set up in the driver’s cabin to ensure the safe operation of the crane.

2. Hoist Trolley:

Lifting mechanism – The hoist is used to lift or lower the goods, which is the most important and basic mechanism in the crane, and its work quality directly affects the working performance of the whole crane. The lifting mechanism is generally composed of a driving device, a steel wire rope winding system, a fetching device and a safety protection device.

Trolley runningn mechanism – It is the power device that drives the hoist trolley. In order to improve the working efficiency of the crane, the speed is generally faster.

3. Bridge Running Mechanism:

The four wheels of the bridge operating mechanism are used as the support of the crane, and two independent drive systems are used to drive the crane separately.

4. Electrical Control System:

Power supply – The standard power supply of our overhead cranes is three-phase AC, the rated voltage is 380V, and the rated frequency is 50Hz. It can also be designed according to user requirements.

Electrical protection system – short circuit protection, loss of pressure protection, emergency power off switch, overload limiter, travel limit switch, zero position and interlock protection, phase failure, phase error, overvoltage, undervoltage protection, ground protection, etc.

The working principle of the lifting mechanism: the electric motor rotates after being energized, the speed is changed by the reducer, and then the drum is driven by the coupling, and the lifting and lowering process of the hook is completed through the wire rope winding system.The working principle of the trolley running mechanism: The motor drives the wheels through the vertical reducer, coupling and drive shaft fixed on the trolley frame.

The transmission type of the bridge running drive system: a motor drives a reducer through a gear coupling and a transmission shaft. The low-speed shaft of the reducer is connected to the wheel shaft with a coupling, and the driving wheel ratio is 1:2. When starting, the driving wheel does not slip, and when braking, it is stable and reliable.

Single Girder Overhead Crane Specifications

Double Girder Overhead Crane Specifications

Overhead crane is engineered to lift and move extremely heavy loads through the overhead space in a facility.It can realize the vertical, horizontal and longitudinal movement of the heavy load, and move it to any position in the facility.

• The overhead crane is driven by the crane motor to move longitudinally back and forth along the tracks on both sides of the elevated runway beams.
• The trolley and lifting mechanism on the main girderare driven by the trolley motor to move along the bridge girder.
• The lifting motor drives the lifting mechanism to raise and lower the load.

Overhead cranes can be classified based on the service class. The work duty of the overhead crane is determined by its load rate and frequency of use, and can be divided into four types: light, medium, heavy and extra heavy:

Light duty – the running speed is low, the use times are few, the full load times are few, and the power-on duration rate is 15%. It is designed for light duty and infrequent service, such as the installation and maintenance in hydropower stations and power plants.

Medium – It often works under different loads, the speed is medium, the work is not too heavy, and the power-on duration rate is 25%, such as the overhead cranes used in general machining workshops and assembly workshops.

Heavy duty – It often works under heavy loads, and the power-on duration rate is 40%, such as overhead cranes used in metallurgical and foundry workshops.

Extra heavy – It often works at the rated load, and the power-on duration rate is 60%, such as the overhead crane for steel mill.

The following are work duty of commonly used overhead cranes:

Hook overhead cranes:

Power station installation and maintenance: A1, A2, A3

Workshop and warehouse: A3, A4 and A5

Heavy workshop and warehouse: A6 and A7

Grab bridge cranes:

Intermittent loading and unloading: A6 and A7

Continuous loading and unloading: A8

Bridge crane for metallurgy:

Feeding: A8

Casting: A6, A7 and A8

Forging: A7 and A8

Cabin operation – All mechanisms are operated by the cam controller or master controller in the cab to control the operation of the hoist, trolley and bridge mechanisms. An emergency stop button is installed in the driver’s cab. Press this button to cut off the power supply of the whole crane in an emergency.

Pendant operation – Press the buttons on the handle to control the actions of the crane’s various mechanisms.

Remote control operation – The corresponding mechanism of the crane is controlled by the industrial remote control.

In addition, the overhead cranes can be equipped with two sets of operating devices, that is, pendant control + remote control or cab + remote control.

However, due to safety issues, the two operating modes can only be switched to use and cannot be used at the same time.

• Metal structure: clean the bridge crane to ensure there is no dust and no yellow robe. Check for cracks and open welding.
• Crane and trolley running mechanisms: check and tighten the transmission shaft seat, gear box, coupling, shaft and key; check and adjust the brake wheel clearance to make it uniform, sensitive and reliable.
• Reducer: check the crane reducer to see if it leaks oil.
• Lifting mechanism: check whether the steel wire rope, hook and pulley are safe and reliable, and if the wear exceeds the specified value, they should be replaced; check and adjust the brake to make it safe, sensitive and reliable.
• Inspection of wire rope: the inspection of the wire rope should focus on the broken wires, wear, kinks, rust, etc. Check whether the safety limiter of the steel wire rope in the drum is effective, whether the steel wire rope pressing plate on the drum is pressed tightly and whether the number of pressing plates is appropriate.
• Lubrication: check the oil quality and quantity of all parts, and add or replace lubricating oil as required.
• Pulley: check whether the wear of the groove bottom exceeds the standard and whether the cast iron pulley has cracks.
• Electrical system: check whether the limit switches are sensitive and reliable, whether the actions of the electrical devices in the electrical box are sensitive and reliable, whether the motor, electric belland wires are safe and reliable, and whether the signal lights are in good conditions.
• Check whether the couplings are loose.

The safety inspection is to ensure the safe operation of the overhead crane. Some safety routine inspections are required during the operation of the crane:

• Each overhead crane must be hung with a sign of the rated lifting capacity in a conspicuous place.
• During work, no one is allowed on the bridge or transporting people with hooks.
• Operators are not allowed to drive overhead cranes without operating licenses.
• The crane is not allowed to be used with overload.
• When the overhead crane is running on a way without obstacles, the hook and the bottom of the hanging object must be at least 2m above the ground. If crossing the obstacle, it must exceed the obstacle by 0.5m.
• Overhead cranes with main and auxiliary hooks do not raise or lower the main and auxiliary hooks at the same time.
• For lifting objects less than 50% of the rated lifting capacity, two mechanisms are allowed to operate at the same time; when lifting objects greater than 50% of the rated lifting capacity, only one mechanism can operateat a time.
• Limit switches and interlock protection devices should be checked frequently.
• When the hook is at the lower limit position, there must be more than two safety rope loops on the drum.
• The voltage of the lighting lamp used for repair and inspection must be below 36V.

• The installation of overhead cranes is performed according to the agreement signed by the buyer and the seller. We can provide installation services or guidance services, and the cost is negotiated and determined by the buyer and the seller.
• Regardless of which party is responsible for the installation, the site must be equipped with a commander in chief and a safety officer. The rest of the installers can be determined according to the scale of the project. The installers must have an installation certificate.
• After the crane is installed, perform the initial trial operation of the crane. Rectify and debug the non-conforming items to meet the requirements of crane use and relevant crane standards.