Single Girder Underslung Crane

 

A Single Girder Underslung Crane is a type of overhead crane designed to be mounted underneath the supporting structure (e.g., a building or steel frame) rather than on top. This configuration provides space-saving advantages and is ideal for applications where headroom or overhead space is limited.

The crane's single girder design makes it lightweight and more cost-effective compared to double girder cranes, while still providing high efficiency.The underslung design ensures that the crane is positioned below the support beams, maximizing vertical space above the crane path.

The main advantage of an underslung crane is its ability to utilize limited overhead space more effectively. It is ideal for low-headroom applications or locations where the ceiling height is constrained.It can be installed in a variety of environments, including warehouses, workshops, and production lines, where headroom is restricted but heavy lifting is required.

The Single Girder Underslung Crane can be mounted directly onto the underside of the building's ceiling or other structural supports, reducing the need for additional structural work.It is made from high-quality materials, single girder underslung cranes are designed for long-term, reliable operation under heavy-duty conditions.

The Single Girder Underslung Crane is equipped with high-quality electric hoists, offering smooth, efficient, and precise control of the load. This minimizes wear and tear and extends the crane's lifespan.

Core Components: Motor

Place of Origin: China

Warranty: 1 Year

Weight (KG): 5000 kg

Video outgoing-inspection: Provided

Machinery Test Report: Provided

After-sales Service Provided: Engineers available to service machinery overseas

Keywords: single girder underslung eot crane

Rated Lifting Moment: 10t

Max. Lifting Load: 10 ton

Max. Lifting Height: 18m

Span: 5-31.5m

 

 

1.Main beam

1) The main beam of a single girder underslung crane is a critical component that supports the load and transfers the forces to the supporting structure. A single girder underslung crane features a single main beam that is suspended from the crane runway structure (usually from the bottom side of the runway beams, hence the term "underslung").The main beam typically runs across the width of the crane bay.

The main beam is usually made of steel, with sections like I-beams, box girders, or trapezoidal sections, depending on load requirements, span, and design.The size of the main beam depends on the crane's lifting capacity, span, and operating conditions. Larger cranes require heavier beams with larger cross-sections to withstand the forces exerted during operation.

3) Underslung Design: Unlike an overhead crane, which has its main girder above the trolley, an underslung crane has the beam below the trolley. This can be beneficial in facilities with low headroom or when space is constrained.The main beam supports the weight of the trolley, hoist, and any load being lifted.It transmits the load forces to the supporting structure (usually the runway system), ensuring stability and safety during crane operation.

2.Lifting System

A lifting system of a single girder underslung crane consists of several key components that work together to move loads efficiently and safely.

Hoist: The hoist is the mechanism that provides the lifting action. It typically consists of:

Motor: Powers the hoisting mechanism.

Reduction Gearbox: Reduces the speed of the motor and increases torque.

Drum or Chain: Where the lifting medium (rope or chain) is wound, lifting and lowering the load.

Brake: Ensures the load is safely held in place when not in motion.

End Trucks：These are the wheels and supports that allow the crane to travel along the runway. The end trucks are mounted at each end of the girder and are connected to the runway tracks. The wheels are often fitted with a specialized bearing system to ensure smooth movement.

Bridge (Girder)：The single girder is the horizontal beam that spans the distance between the supports (rails or columns). It carries the load from the hoist and is typically made of steel for its strength and durability. The underslung design means the crane is mounted under the runway beam, as opposed to being on top of it, which provides a more compact structure and allows for a higher lifting height.

Trolley:The trolley is the component that moves the hoist along the bridge girder. It is typically motorized and travels in the horizontal direction (cross travel), allowing the hoist to cover the entire span of the crane.

3.End carriage

The end carriage of a single girder underslung crane refers to the part of the crane that supports the girder and houses the wheels or rails for the movement of the crane along its tracks. This end carriage is typically mounted on both ends of the crane girder and is designed to move along the runway, which is usually installed on the ceiling or overhead structure.

The end carriage provides the necessary support for the crane girder and helps distribute the weight of the crane and the load.The end carriage is fitted with wheels that run on rails (typically suspended or mounted on the building's overhead structure).In many cases, the end carriage will have a motorized drive system, allowing it to move along the runway. It can either be equipped with a single drive motor or be manually operated.

The end carriage is designed to allow smooth, controlled movement of the crane along the runway, ensuring the correct alignment during operation.It transfers the load carried by the crane to the tracks or suspension system, ensuring that the load is evenly distributed.

 

4.Crane travelling mechanism

1) Operation principle

The crane operates by using the electric motor to drive the trolley across the track. The hoist on the trolley can be moved up and down to lift or lower loads.The system is designed for smooth and controlled movement to ensure efficient material handling, often in areas where space or headroom is limited, making underslung cranes ideal for use in factories or warehouses with overhead structures.

2) Functional characteristics

Support and Stability：The traveling mechanism is mounted on the underside of the crane girder, typically supported by rails or beams, and ensures stable movement of the crane along its travel path.

It includes wheels or trolley assemblies that run along the supporting track, which helps to distribute the load evenly to prevent excessive wear or instability.

Drive System：Electric Motor: Most underslung cranes use an electric motor to drive the travel mechanism. The motor is usually coupled with a reduction gear to reduce speed while increasing torque for smooth operation.

Variable Speed Control: The travel mechanism may be equipped with variable speed control to allow for precise positioning and adjust the travel speed of the crane.

Braking Mechanism: A braking system is essential to stop the crane safely, especially when it is moving on inclined tracks or requires precise stopping. This can include both dynamic and mechanical brakes.

5.Trolley travelling mechanism

Structural composition

Trolley Frame:The trolley frame is the main supporting structure that houses the trolley components. It is typically made of steel to provide the necessary strength and rigidity. The frame supports the hoisting mechanism and ensures the proper alignment of the trolley.

Trolley Wheels:The trolley is equipped with wheels that run along the crane's girder. These wheels are typically mounted on both sides of the trolley frame and are designed to bear the load while ensuring smooth travel. The wheels are usually made of high-strength steel and may be fitted with bearings for reduced friction.

Drive Motor and Gearbox:The trolley is driven by an electric motor that powers a gearbox, which in turn drives the wheels. The motor and gearbox are typically mounted on the trolley frame. This system is responsible for providing the necessary movement to travel along the girder.

End Trucks:These are the structural components located at each end of the trolley. They support the trolley wheels and the drive mechanism. The end trucks help distribute the load and facilitate smooth travel along the girder.

Trolley Rail(s):The trolley typically travels along a set of rail tracks that are fixed to the girder. These rails guide the trolley and help maintain its stability during operation. The rail design and alignment are crucial for ensuring smooth movement and minimizing wear on the wheels.

Power Supply System:This consists of the electrical wiring and control systems that provide power to the motor driving the trolley. The power supply may be delivered through a conductor rail system or through cables, depending on the crane design.

Braking Mechanism:A braking system is installed to stop the trolley when required. It can be mechanical, electrical, or a combination of both, ensuring the trolley stops smoothly and safely when needed. The brakes are mounted on the trolley wheels or on the motor and gearbox assembly.

Function of the trolley operating mechanism

Trolley Movement (Horizontal Travel):The primary function of the trolley travelling mechanism is to allow the trolley to move horizontally along the bridge girder. The trolley is mounted on the underside of the girder (hence "underslung"), and the movement is typically powered by an electric motor driving a gear system.

Motors and Drives:The trolley is powered by an electric motor connected to a drive system, which may include a worm gear, helical gear, or a chain drive. The motor provides rotational motion, which is converted into linear motion through the drive mechanism to move the trolley.

Guide Rollers or Wheels:Guide rollers or wheels are installed on the trolley and run along the underside of the crane girder. These are designed to ensure the smooth movement of the trolley along the girder while maintaining stability and preventing any lateral displacement or misalignment.

Load Carrying Capacity:The trolley is designed to carry loads while maintaining its stability and ensuring precise travel along the girder. The wheels and drive components are engineered to handle the expected load range without excessive wear or deformation, ensuring long-term durability.

5. Speed Control:

Speed control mechanisms allow for adjusting the speed of the trolley's travel, which is critical for ensuring precision during operations. This is typically managed by a variable frequency drive (VFD) or a similar control system that adjusts motor speed based on operational needs.

6.Crane wheel

A crane wheel of a single girder underslung crane is a crucial component that supports and guides the movement of the crane along its track.

The crane wheel is designed to facilitate the movement of the crane along its rail track, allowing for horizontal transportation of loads within a workspace.In an underslung crane, the crane's main girder is mounted below the runway rails, which is why the wheels are often positioned differently compared to an overhead crane. These wheels allow the crane to move smoothly along the track without the need for a large support structure overhead.

Crane wheels are typically made from high-strength steel or cast iron to withstand the heavy loads and constant movement.They are usually cylindrical and may feature a flange on the inner side to keep them aligned with the track.The wheels are often equipped with high-quality bearings that help reduce friction and ensure smooth rotation.

The design of the wheel, including its diameter and material composition, is determined based on the maximum weight the crane is expected to lift and move.

7.Crane Hook

A crane hook in the context of a single girder underslung crane is the component that holds and lifts the load. In an underslung crane, the crane rails are mounted beneath the overhead structure (the girder) rather than on top, allowing for the crane to operate in spaces with limited headroom.

The hook is typically made of high-strength steel or alloy material to withstand heavy loads.It is designed to securely hold the load with a tapered or rounded shape to reduce the risk of slippage.Some hooks may feature a safety latch that prevents the load from accidentally detaching.

The hook is designed to handle specific load capacities, which depend on the crane's overall lifting capacity.These capacities are often marked on the hook, along with other safety markings.

The hook is connected to the hoisting mechanism (such as a chain, rope, or wire rope) that raises and lowers the load.It is mounted to the trolley or hoist block which travels along the girder.

8.Motor

The motor of a single girder underslung crane is a critical component that provides the necessary power to lift and move loads.

The motor powers the crane's trolley or hoist system, enabling the movement of the load along the girder.It is designed to deliver a specific amount of torque and speed to ensure smooth and safe operation of the crane.

AC Motors:Common in overhead cranes, offering reliable, continuous operation.Can be designed for both variable or fixed speeds.Used for cranes requiring long duty cycles.

DC Motors：Provide better speed control and are generally used when precise control is needed, especially in applications requiring variable speed.Often used for small or specialized cranes.

Brake Motors:Motors integrated with a braking system to stop the crane quickly and safely after load lifting or lowering operations.Typically used for hoisting and lowering loads.

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9.Sound and light alarm system & limit switch

1) Sound and light alarm system

Sound Alarm (Horn or Siren): The sound alarm serves to alert people in the surrounding area when the crane is in operation or if there is a hazardous condition. It is often used to warn of crane movements, lifting operations, or any emergency situations.Typically consists of a loud horn or siren that emits a high-pitched sound.Can be triggered by specific crane movements (e.g., hoisting, lowering, traveling).Often designed to work in environments with high ambient noise, ensuring that it is still audible to nearby workers.May have adjustable volume or sound patterns (e.g., continuous or intermittent).

Light Alarm (Strobe or Flashing Lights):Light alarms complement the sound alarm by providing a visual warning, which is especially useful in noisy environments or when people may not hear the sound alarm clearly.Typically involves a bright flashing light or strobe light.Can be mounted on the crane itself or nearby structures.Often linked to the operation of the crane to signal specific activities (e.g., when the crane is in motion, during lifting, or in emergency situations).Different light colors (e.g., red, yellow, or blue) can be used to indicate different states or levels of alert (e.g., red for danger, yellow for warning).

2) Limit switch

A limit switch in a single girder underslung crane is an essential safety component that ensures the crane operates within its safe working range, preventing over-travel or damage to the crane's structure.

Function of Limit Switches:

End of Travel Detection: The limit switch is typically installed at both ends of the crane's travel path. It detects when the crane trolley or hoist has reached the maximum or minimum point along the girder or track.

Prevents Overtravel: When the crane reaches the end of its travel limit, the limit switch will activate and signal the crane's control system to stop further movement in that direction.

Safety Cutoff: This action helps prevent mechanical damage or safety hazards caused by over-traveling, such as stressing the crane's structural components or interfering with other equipment.

10.Safety Devices

1. Overload Protection：Overload Limit Switch: This device prevents the crane from lifting loads that exceed the maximum rated capacity. If the load is too heavy, the crane will automatically stop operating, preventing damage or accidents.

2. Limit Switches：End of Travel Limit Switch: These switches are installed to stop the crane's motion when it reaches its maximum travel distance in either direction (horizontal or vertical), ensuring it does not run into obstacles or damage other equipment.

Hoist Limit Switch: Prevents the hoist from raising or lowering beyond the safe limits, protecting the load and crane components.

3. Emergency Stop (E-Stop) Button：A safety feature that immediately stops the crane's operation in case of an emergency. This button can be triggered manually by the operator or automatically if the system detects a safety hazard.

4. Safety Brake System：The crane includes mechanical or electrical brakes that activate if there is a failure in the system (such as power loss). These brakes prevent the load from falling or shifting unexpectedly.

5. Anti-Sway System：Some advanced cranes are equipped with anti-sway technology to reduce the oscillation or swinging of the load, especially when moving long or heavy materials. This helps prevent accidents and load damage.

6. Crane Load Indicator (CLI):This device monitors and displays the current load on the crane in real time. It warns the operator if the load exceeds the safe lifting limit and helps prevent overload conditions.

7. Pendant Control with Dead Man's Switch:The crane's pendant control typically includes a "dead man's switch" feature. If the operator releases the switch, the crane automatically stops, preventing accidents if the operator becomes incapacitated.

8. Emergency Power Supply:In case of power failure, a backup power supply (such as a battery or generator) ensures that the crane can still be safely operated to lower the load and bring the system to a stop.

11.Control Mode

1. Cabin Control (or Pendant Control)

The operator controls the crane from a control cabin or via a handheld pendant controller.

The cabin is typically positioned at one end of the crane, while the pendant control allows for remote operation.

This mode is used for better visibility and control of operations in certain environments.

Advantages: Better control of movement, safety features, easy to operate.

Disadvantages: May limit the operator's range of motion or access to certain areas.

2. Radio Remote Control

The operator uses a radio transmitter to control the crane from a distance, providing flexibility and better visibility.

This is particularly useful in situations where the operator needs to move around the crane or be in a specific position for safety or operational purposes.

Advantages: Enhanced flexibility, mobility, and safety.

Disadvantages: Potential for signal interference or range limitations.

3. Fixed Control Station

The crane can also be operated from a fixed control panel located near the crane structure.

This mode is common in environments where the crane is used in a dedicated workspace or on a fixed track.

Advantages: Simplicity and reliability.

Disadvantages: Limited mobility for the operator.

4. Automatic Control

In more advanced systems, the crane can be controlled automatically via sensors or predefined programming. This allows for tasks to be carried out without direct human intervention.

Advantages: Increases productivity, reduces human error, and optimizes operations.

Disadvantages: High upfront cost, complex maintenance.

5. Joystick or Touchscreen Control

Some cranes, especially in modern systems, come with joystick or touchscreen interfaces, which can make operation more intuitive and efficient.

12.Sketch

 

13.Main technical

 

Space Efficiency: The crane is mounted below the runway beams, making it ideal for facilities with limited headroom or where maximizing overhead space is important. This is particularly useful in buildings with lower ceilings or areas where ceiling-mounted equipment (like HVAC or lighting) could interfere with a top-running crane.

Reduced Building Structure Load: Since the crane hangs from the underside of the runway beams, the overall load on the building structure is generally lower than that of an overhead crane. This can be beneficial in buildings that have limitations on load-bearing capacity.

Compact Design: The single girder design is typically more lightweight and compact compared to a double girder system. This can lead to cost savings in terms of material and installation, and it also requires less space for operation.

Lower Maintenance Costs: With fewer components and simpler design compared to double girder cranes, single girder underslung cranes generally have lower maintenance costs and require less upkeep over time.

Smooth and Precise Operation: The crane's structure allows for smoother movement along the tracks, providing precise control of the load, which is crucial for certain industrial applications.

Cost-Effective: The single girder design uses less material and is typically more affordable in terms of both initial cost and operational efficiency compared to more complex systems like double girder cranes.

Flexibility in Space Utilization: Since the crane doesn't require a lot of vertical space for installation, it allows for better use of floor space in the warehouse or factory.

Quieter Operation: Single girder cranes generally operate more quietly compared to larger, more complex systems, making them suitable for environments where noise reduction is important.

Easy Installation: Due to the lighter weight and simpler design, installation is usually quicker and more straightforward compared to larger cranes.

 

 

Warehouse and Distribution Centers:

Ideal for applications in warehouses with low ceiling heights where headroom is limited.

Used for moving materials, heavy goods, or packages from one location to another.

Manufacturing Plants:

Useful in factories where space efficiency is important, such as automotive or electronics production.

Helps in lifting and moving parts or products along an assembly line.

Workshops and Small Factories:

In workshops with low ceilings, underslung cranes provide a compact lifting solution without the need for costly structural modifications.

Lifting small to medium-weight loads, such as machinery, tools, or components.

Logistics and Shipping Operations:

Used in loading and unloading heavy goods from containers, trucks, or shipping vessels where space constraints exist.

Also common in port handling, especially in smaller, more compact areas.

Construction Sites:

Can be installed in places with limited headroom, like underneath existing structures, to lift building materials such as steel beams or concrete blocks.

Foundries and Steel Mills:

Useful for lifting molten metal containers or heavy steel materials where precise control over load movement is needed.

 

 

1. Design and Engineering

Requirement Analysis: Understand customer specifications such as load capacity, span, lifting height, and environment (e.g., indoor, outdoor, temperature considerations).

Structural Design: Design the crane's structure including the single girder, end trucks, hoist, and other components based on the provided specifications.

Selection of Materials: Choose materials based on load-bearing requirements and durability, typically high-strength steel for the girder and components.

System Design: Engineering design of the electrical system, hoist mechanisms, safety features (limit switches, overload protection, etc.), and control systems.

2. Procurement of Materials

Order raw materials such as steel plates, beams, motors, gears, electrical components, and hoisting mechanisms.

Verify that all materials meet the required quality standards for strength, durability, and safety.

3. Fabrication of Components

Girder Fabrication: Cut, weld, and assemble the single girder. This is often the largest part of the crane and must be precisely fabricated to ensure correct alignment and balance.

End Truck Manufacturing: Fabricate and assemble the end trucks (the units that carry the crane along the tracks). These are typically made from steel and must be fitted with wheels that will roll along the crane track.

Hoist Assembly: Assemble the hoist mechanism, including the motor, gearbox, lifting drum, and rope. This also involves configuring the controls for lifting and lowering.

Electrical and Control Systems: Install the control panels, wiring, and other electrical components. This includes the integration of limit switches, safety devices, and communication systems (e.g., remote control or pendant).

4. Assembly of the Crane

Gantry and Crane Frame: Assemble the single girder and the end trucks to create the frame of the crane.

Hoist Mounting: Attach the hoisting mechanism to the girder structure.

Rail and Track Installation: If the crane is to be mounted on rails, the tracks must be installed and aligned.

5. Testing and Quality Control

Static Load Testing: Perform tests to ensure the crane can handle the specified load without deforming or failing.

Dynamic Testing: Test the crane under load while operating (lifting, moving, etc.) to ensure smooth operation and functionality.

Electrical and Control Tests: Ensure the electrical systems function correctly and safely. Check all limit switches, sensors, and controls.

Safety Tests: Verify safety features such as overload protection, emergency stop functions, and braking systems.

6. Painting and Finishing

Surface Preparation: Clean and prepare all steel surfaces to prevent corrosion.

Painting: Apply a protective coat of paint, typically a high-quality industrial paint that is resistant to the operating environment (e.g., weatherproofing for outdoor use).

Marking and Labeling: Mark the crane with safety labels, load capacities, and manufacturer information.

7. Final Inspection

Inspect the entire crane to ensure all components are correctly installed and that the crane complies with safety regulations and customer specifications.

Ensure all documentation is in order, including user manuals, maintenance instructions, and certification of testing.

8. Delivery and Installation

Transport: Ship the crane to the installation site, ensuring it is properly packed and protected during transit.

Installation: On-site installation includes mounting the crane on its tracks (if applicable), connecting power supply, and ensuring proper alignment and operation.

Commissioning: Perform final operational testing on-site and hand over the crane to the customer. Ensure the customer is trained on how to operate and maintain the crane.

9. Post-Installation Support

Provide after-sales support, including maintenance services, troubleshooting, and spare parts.

Workshop view:

The company has installed an intelligent equipment management platform, and has installed 310 sets (sets) of handling and welding robots. After the completion of the plan, there will be more than 500 sets (sets), and the equipment networking rate will reach 95%. 32 welding lines have been put into use, 50 are planned to be installed, and the automation rate of the entire product line has reached 85%.