A Deep Dive into Double Girder Overhead Crane Types and Innovations

Double girder overhead crane, also known as double girder bridge crane or double girder EOT crane is a type of overhead crane that has double beams instead of one. In general, double girder cranes are used for heavy-duty applications, which means components are more complex, driving the cost of this type of crane higher. A double girder overhead bridge crane configuration is made up of two bridge girders, two end trucks, and a trolley hoist assembly.

Double Girder Overhead Crane Types

The double girder overhead crane is the most commonly used type of overhead crane. It can be categorized based on the trolley type into hoist trolley and winch trolley types. If you are purchasing in China, there are two different types of double girder overhead cranes: LH type for hoist trolley and QD type for winch trolley.

LH-type double girder overhead crane with hoist trolley	QD-type double girder overhead crane with winch trolley

LH-type Double Girder Overhead Crane With Hoist Trolley

• Capacity: 5-32/5ton
• Span length: 10.5-31.5m
• Lifting height: 3-50m
• Work duty: A3, A4
• Rated voltage: 220V~690V, 50-60Hz, 3ph AC
• Work environment temperature: -25℃～+50℃, relative humidity ≤85%
• Crane control mode: Floor control / Remote control / Cabin room

For more detailed specifications, please refer to DGCRANE's catalog of LH-type double girder overhead cranes.

LH double girder overhead crane parameter table

QD-type Double Girder Overhead Crane With Winch Trolley

• Capacity: 5-800/150ton
• Span length: 10.5-31.5m
• Lifting height: 3-50m
• Work duty: A5, A6
• Rated voltage: 220V~690V, 50-60Hz, 3ph AC
• Work environment temperature: -25℃～+50℃, relative humidity ≤85%
• Crane control mode: Floor control / Remote control / Cabin room

For more detailed specifications, please refer to DGCRANE's catalog of QD-type double girder overhead cranes with hook.

QD double girder overhead crane parameter table

Double Girder Overhead Crane Solutions for Various Industry Scenarios

LH-type hoist trolley double girder overhead cranes and QD-type winch trolley double girder overhead cranes are two types that can meet the lifting requirements of hooks in most working conditions. Double girder overhead cranes can also be equipped with different lifting devices and trolley designs, suitable for customized solutions in different industries. Here are several special cases applicable to the metallurgical and prefabrication industries.

QE Double Trolley Metallurgical Double Girder Overhead Crane for Transporting Scrap Steel Ladles in Steel Plants

Drawing of 50ton+50ton QE double trolley metallurgical double girder overhead crane

Product Parameters Product Category: HB(BCD) Product Parameters Type: QE double trolley metallurgical double girder overhead crane Lifting capacity: 50ton+50ton Span: 21.5m Lifting height: 22m Lifting speed: 1.26-12.6m/min Traveling speed: 3.8-38m/min (main crane), 7.8-78 m/min (auxiliary crane) Work duty: A7 Operating mode: Cabin control (double-layer insulated closed cabin)

For the special environment of high temperature and high dust, as well as the practical use, the customer has made some special requirements for the technical specifications of this double girder bridge crane:

• This double girder bridge crane is mainly used for lifting scrap steel ladle and converter, so it is required that the main hook and auxiliary hook must have the same gear and speed.
• The customer requires that except for special requirements, all components of the crane must be interchangeable with the existing 50+50t crane to reduce the communication cost of procurement during later maintenance.
• Due to the special nature of the metallurgical environment with high temperatures and high dust, the power supply of the crane trolley uses a copper-steel sliding contact line.
• To ensure the stability and non-tilting of the ladle during the operation of the crane, electronic scales are installed on the main hook and auxiliary hook, with sensors installed on the fixed pulleys, equipped with wire rope compensators and wireless transmitters. The outdoor control room is equipped with a large screen to display the actual weight of the lifted objects, and the transmitting device sends data wirelessly to the ground control room. It is equipped with a wireless receiving device for electronic scales and a 4-20mA converter.
• Safety is paramount in the metallurgical workshop. The crane has a complete set of protections including short circuit protection, overload protection, under-voltage protection, zero position protection, travel limit protection, emergency power-off protection, safety switch for railing door, overload protection, descent limit protection, and descent overspeed protection.
• The lifting system adopts a stator pressure regulating and speed regulating system with four-speed settings: 10%, 20%, 30%, and 100%. It adopts a dual-loop (primary and backup) control mode, so that when one loop fails (the power and control loops of the faulty loop are completely cut off), it can switch to the other loop for normal operation. The selection of each speed control mechanism must fully consider the power margin to meet the harsh operating environment of the user unit.
• The traveling system of both the main and auxiliary trolleys adopts a variable frequency speed control system (two sets of frequency converters for the main trolley, and it is required that when one set is used alone, the capacity meets the requirements of the entire crane operation). Resistors are installed on both the input and output ends of the switch quantity control to suppress current surges and prevent large impacts on the power grid, thereby protecting electrical components.

QD Fully Automatic Unmanned Double Girder Overhead Crane for Vanadium Product Factory Lifting Vanadium Nitrogen Alloy Balls

Drawing of 4ton QD unmanned double girder overhead crane

Product Parameters Type: QD fully automatic unmanned double girder overhead crane Lifting capacity: 4ton Span: 13.5m Lifting height: 9m Lifting speed: 1.35-13.5m/min Traveling speed: 7.4-74m/min (trolley) 2.86-28.6m/min (crane) Work duty: A7 Operation mode: Fully automatic unmanned Operation price: 1,738,000 RMB

This case utilizes an automatic feeding mechanism and unmanned control double girder bridge crane to complete the loading and precise positioning of the vanadium-nitrogen alloy ball hopper, meeting the production process requirements. Some other specific requirements from the customer include:

• Control System: The control system consists of a PLC. The PLC communicates with the upper computer via Ethernet. The control system is responsible for identifying, positioning, and anti-swaying of the hoisted objects. There are three operation modes for unmanned crane operation: on-site remote control operation, remote operation by personnel, and automatic operation according to upper computer instructions.
• Anti-sway Control System: The anti-sway control system needs to detect the swinging state of the steel rope in real-time, control and adjust the acceleration and deceleration of the unmanned crane, reduce the swing of the hoisted object during lifting, and accurately position it at the target location, making the lifting process faster and smoother.
• Motors: The system uses variable frequency motors or servo motors. The lifting mechanism adopts a dual-axis motor to ensure that the two sets of winches operate at the same speed.
• External Sensors: Including WCS encoders, lifting absolute encoders, weighing sensors, limit switches, etc. These sensors can mainly be divided into two categories: one is responsible for the safety of unmanned crane operation, such as weighing sensors and limit switches; the other is to ensure the precise positioning of unmanned cranes, such as WCS encoders and lifting absolute encoders. WCS encoders must-have cleaning and to blow devices.
• Accuracy of Unmanned Crane: The positioning accuracy of the trolley and crane running mechanism is ±5mm, and the positioning accuracy of the lifting mechanism is ±5mm.
• Production Cycle Time: Complete one production cycle time ≤ 15 minutes.
• Considering the large amount of graphite dust in the unmanned crane working environment, protective measures need to be taken for the electrical control system. Specific measures include:
  • The inner side of the ventilation openings of the electrical control cabinet is equipped with a dust-proof net, which needs to be easily removable for regular cleaning in the later period;
  • All inlet and outlet ports of the electrical control cabinet need to be sealed;
  • All components in the electrical cabinet must use explosion-proof electrical appliances to fundamentally prevent the harm caused by graphite dust;
  • Install a protective cover for the camera, and regularly clean the protective cover.
  • The protection level of motors, reducers, encoders, and limit switches is not lower than IP54.

Steel Direct Dispatch Warehouse Crane for Handling Standard-length Steel with QC Upper Rotating Electromagnetic Beam Double Girder Overhead Crane

Drawings of the 12.5ton+12.5ton QC upper rotating electromagnetic suspended double girder overhead crane

Product Parameters Type: QC upper rotating electromagnetic suspended double girder overhead crane Capacity: 12.5ton+12.5 ton Span: 31.5m Lifting height: 10m Lifting speed: 16.2m/min Traveling speed: 94.7m/min (main trolley), 0.22-2.2 r/min (upper trolley), 43m/min(lower trolley) Working Duty: A7 Control Method: Cabin Operation Price: 1,425,000 RMB

The main function of the steel direct distribution center is to centrally store steel of various specifications and models, and distribute and ship them promptly according to customer orders. The electromagnetic bridge double-girder crane is used for hoisting and shipping steel of fixed lengths in the steel direct distribution center. The entire vehicle running mechanism motor requires electrical control by a frequency conversion control device.

The upper rotating electromagnetic suspended crane follows the design specifications of GB/T 3811-2008 "Crane Design Specification" and GB/T 14405-1993 "General Bridge Crane" and other national and industry standards. It is suitable for indoor or outdoor fixed spans in steel plants, yards, and warehouses, for loading, unloading, and transporting materials such as steel plates, profiles, and coils. It is particularly suitable for lifting materials of different specifications and requiring horizontal rotation. The lower part of the suspended beam can carry special lifting equipment such as electromagnetic suction cups and clamps.

The electromagnetic iron magnetization system mainly consists of a control cabinet and a battery. When the electromagnet is used normally, the rectifier circuit in the control cabinet charges the battery. When the external power supply fails, the electromagnetic control system will automatically switch the electromagnet to battery power supply to ensure that the lifted object does not drop due to sudden power failure. According to user requirements, an inverter power supply can be installed for the electromagnetic retention system so that the operator can open the hoisting mechanism brake and lower the lifted object to the ground in case of power failure.

The running mechanism adopts normally closed hydraulic push rod block brakes; the hoisting mechanism adopts hydraulic push rod block brakes. The braking requirements are smooth and reliable. After three full compression tests, the spring used in the brake must not have permanent deformation. The contact area of the assembled brake lining with the brake wheel is not less than 70% of the total area. The rotation of each hinge point of the brake should be flexible.

QZ Grab Bucket Double Girder Overhead Crane for Use in Cement Plants

Drawings of 10ton grab bucket double girder overhead crane

Product Parameters Type: QZ Grab bucket double girder overhead crane Lifting capacity: 10ton Span: 31.5m Lifting height: 18m Lifting speed: 29m/min Traveling speed: 89m/min (for the main crane), 45.6 m/min (for the trolley) Work Duty: A6 Price: ¥301,700 Operating mode: Cabin control

This double girder overhead crane is suitable for industries such as metallurgy, building materials, chemical industry, and coal mining. It is used for loading and unloading bulk materials such as ores, slag, coke, coal, and sand in workshops, warehouses, or outdoor areas with fixed spans.

The power supply of the double girder overhead crane adopts a three-phase four-wire (3P+PE) AC 380V, 50HZ. The power supply is introduced into the main power distribution cabinet of the crane by the sliding wire, and then power is distributed to the main, lighting, and auxiliary circuits. The crane is designed with all cables and wires concealed, with the cables for the large and small cars routed in galvanized wire troughs. The motors and overload lines are protected by steel-reinforced hoses to prevent cable damage caused by human factors and extend the service life.

If you have similar needs as described above, feel free to contact your dedicated customer service representative at any time.

Zora Zhao

Expert in Overhead Crane/Gantry Crane/Jib Crane/Crane Parts Solutions

With 10+ years of experience in the Crane Overseas Export Industry, helped 10,000+ customers with their pre-sales questions and concerns, if you have any related needs, please feel free to contact me!

WhatsApp: +86 158 3611 5029

Email: zorazhao@dgcrane.com

More Double Girder Overhead Crane Design Solutions

Clamp double girder overhead crane

QB explosion-proof double girder overhead crane

QY insulated double girder overhead crane

Interpretation of models frequently mentioned in Chinese procurement

• NLH — Double girder electric hoist overhead crane with European style design with a capacity of 3 ton -80 ton, with a lower profile than LH type.
• LH— Double Girder electric hoist bridge crane with CD/MD wire rope hoist trolley, with a capacity of 3 tons -63 tons, a cheaper solution than NLH.
• QDX — Double girder overhead crane with European style open winch trolley with capacity of 3 ton -320 ton lower headroom with QD type hook crane.
• QD —Universal Double Girder Hook Overhead Crane for General Use with a capacity from 3-ton to 550-ton
• QDY —Casting bridge crane for hot ladle handling with a capacity of 3 ton -74 ton
• YZ — Double Girder Overhead Casting Crane with Capacity of 75 ton -320 ton
• QZ— Grab bridge crane with double girder crane design with orange peel grab or clamshell grab bucket for bulk loads handling
• QB— Explosion-proof bridge crane with explosion-proof design for hazardous applications with a capacity of 5 ~ 75 tons
• QE— Double Girder bridge crane with Double Open Winch for Tandem Lifting with a capacity of f (2.5+2.5)~(200+200) tons
• QY— Insulated double girder bridge crane for smelting workshops of electrolyzing nonferrous metal, aluminum, and magnesium with a capacity of 1 ton -50 Ton
• QC— Electromagnetic Bridge Crane for steel meta handling, used in steel mill or steel scrap yard for steel scrap handling
• QG— Hanging girder bridge crane for long and awkward load handling with lifting beam and lifting spreader
• QL— Electromagnetic hanging beam bridge crane for long and heavy loads handling such as steel pipe, steel plate, etc.
• SQ— Manual double girder crane for workshops or warehouses where there is a shortage of electric power or an explosion-proof crane is required.