Underhung Bridge Crane

 

 

An underhung bridge crane is a highly versatile and space-efficient material handling solution, widely used in industries requiring the lifting and transportation of heavy loads. Designed to operate with its track system mounted on the underside of the building's roof or other supporting structure, underhung cranes maximize floor space and optimize workflow in confined or congested areas.

Underhung bridge cranes are manufactured with high-quality materials to withstand harsh industrial environments and heavy-duty applications. The compact design and configuration of the underhung bridge crane allow it to operate in low-headroom spaces, making it an ideal choice for facilities with limited headroom.

Underhung bridge cranes use advanced control systems to ensure accurate load handling and enhanced operational safety. They are available in a variety of lifting capacities and spans to meet a variety of industrial needs.

The underhung bridge crane is an innovative solution for industries looking to maximize efficiency, safety, and space utilization in their operations.

Core Components：PLC, Bearing, Gearbox, Motor, Gear

Place of Origin：Henan, China

Warranty：1 Year

Weight (KG)：500 kg

Video outgoing-inspection：Provided

Machinery Test Report：Provided

Color：Customized

Crane feature：Easy Operated Girder Bridge Crane

Capacity：1-20t

Type ：Single Girder

Power supply：110V/220V/230V/380V/440V

Control Method：Ground Control+ Remote Control (customized)

MOQ：1 Set

Lifting mechanism：Electric Hoist

Work Duty：A3-A4

 

 

1.Main beam

1) The main beam of an underhung bridge crane is a critical structural component that spans the gap between the crane's supporting structures, such as runway beams or walls. Unlike a top-running bridge crane, an underhung crane has its end trucks mounted underneath the runway beams allowing the main beam to hang below the overhead structure.

Structural Design:Made from steel, often as a single girder (I-beam) or double girder for heavier loads.Designed to carry the load's weight and distribute it evenly to the end trucks.

Suspension System:The beam hangs beneath the runway rails and is supported by wheels on the end trucks that travel along the underslung rails.The suspended design provides flexibility for installations with limited headroom.

Load Capacity:The design and size depend on the crane's load capacity, span, and application.Larger capacities may require reinforced or box girders to prevent deflection and stress.

Integration with Hoist:Supports an electric or manual hoist that moves horizontally along the beam.The hoist mechanism is designed for precise lifting and positioning of loads.

 

2.Lifting System

Motor: The motor is responsible for powering the lifting mechanism, enabling the crane to raise, lower, or hold loads. Its performance impacts the crane's efficiency, precision, and safety.

Reducer: The reducer in a lifting system for an underhung bridge crane plays a critical role in the crane's mechanical system by reducing the high input speed from the motor to a lower output speed, thereby increasing torque. This is essential for lifting heavy loads and ensuring smooth operation.

Drum: The drum lifting system in an underhung bridge crane is a critical component that handles the lifting and lowering of loads.A cylindrical component around which the wire rope or cable is wound.Made of high-strength steel to withstand load stresses.Often grooved to ensure proper winding of the rope and to minimize wear.

Wire rope:The wire rope in the lifting system of an underhung bridge crane plays a critical role in ensuring the safe and efficient operation of the crane. It must handle high tension and wear without failure to prevent accidents.The wire rope is responsible for transferring the force from the hoist mechanism to the load being moved.

Pulley block:These are grooved wheels designed to guide the wire rope or chain.They reduce the effort needed to lift a load by spreading the tension across multiple sections of rope.Usually made of durable materials like steel or high-strength alloys.The pulley block typically hangs below the hoist trolley, which moves along the bridge.

Lifting device: The lifting device of an underhung bridge crane is a critical component responsible for hoisting and lowering loads safely and efficiently. In the context of an underhung bridge crane, the lifting system is typically designed to optimize the use of space and enhance versatility in applications such as warehouses, workshops, and manufacturing facilities.

 

3.End carriage

1) The end carriage of an underhung bridge crane is a critical component that provides support and mobility to the crane bridge. Underhung bridge cranes, also known as underhung cranes, have their bridge suspended from the building structure or runway beams, allowing for efficient space utilization in facilities with limited headroom.

2) The end carriage is designed to be suspended from the overhead runway beams.Typically equipped with wheels that run on the bottom flange of the I-beams.

3)Some end carriages allow for slight adjustments to align with the runway system, ensuring smooth operation.The end carriage is connected to the bridge girder(s), forming a complete crane system.Connections are bolted or welded for secure attachment.

4.Crane travelling mechanism

1) Working principle

The crane is mounted on the underside of a bridge or track system, which is typically supported by overhead beams or rails. In an underhung crane, the bridge is suspended or "underhung" from the overhead structure, rather than being supported from the ground.The crane typically runs along rail tracks or beams installed on the bridge. These rails are supported by the overhead structure, providing a fixed path for the crane to travel horizontally. The traveling mechanism involves the use of wheels or trolleys mounted on the underside of the bridge. These wheels are connected to motors and drive systems, enabling the crane to move along the bridge's length.The movement of the crane is driven by an electric motor or a set of motors. These motors are typically connected to the wheels via a gear mechanism. The motor's power is transmitted to the wheels, causing them to rotate and move the crane along the rails.The motor may be mounted on the crane bridge itself or on the traveling trolley, depending on the design. It may also use a combination of electric, hydraulic, or pneumatic systems for movement.The operator controls the traveling mechanism using a control panel or remote control system. This control adjusts the speed and direction of the motor(s) that drive the trolley wheels.

2) Functions of the crane operating mechanism

Hoisting Mechanism (Lifting) Function:The travelling mechanism allows the entire bridge of the underhung crane to move horizontally along the runway beams.This movement expands the crane's working area, enabling it to handle loads across the entire span of the workspace.

Load Positioning Function: By moving the bridge and the hoist mechanism together, the crane operator can position the load accurately over the desired location.This is essential for precision handling and efficiency in industrial or manufacturing operations.

Smooth Load Transfer:The mechanism ensures smooth and controlled travel to prevent jerky motions that could damage the load or create unsafe conditions.It incorporates wheels or rollers with low-friction bearings for smooth movement.

Load Distribution:The travelling mechanism evenly distributes the weight of the load across the runway beams.This reduces the risk of structural stress or damage to the crane and supporting structures.

 

5.Trolley travelling mechanism

1) Structural composition

Trolley Frame:The trolley frame is the main structure that supports all other components of the trolley system, including the hoist, wheels, and drive system.It is typically made of welded steel to withstand heavy loads and is designed to be rigid for stability during operation.The frame houses the hoist unit and provides a platform for other mechanical elements.

Travelling Wheels (Trolley Wheels): These wheels are mounted on both sides of the trolley frame and allow the trolley to move along the rail track on the underhung bridge.The wheels are usually made of steel and are fitted with bearings to reduce friction and wear.They are positioned to ensure smooth movement along the track, with adjustable wheel spacing for proper alignment with the bridge's girder.

Drive Mechanism (Electric Motor and Gearbox):The trolley is typically driven by an electric motor, often using a geared system that transmits power to the wheel.The motor may be mounted on the trolley frame or on a separate drive unit connected to the trolley via a shaft or chain.The drive mechanism provides the necessary torque to move the trolley across the bridge.

Trolley Rail:The trolley travels on a rail system, usually installed along the underside of the bridge structure. The rails are aligned to ensure smooth and stable movement of the trolley.These rails are often made of high-quality steel to handle the loads imposed by the crane system.

Gearbox and Couplings:The gearbox reduces the speed of the motor and increases torque, which is transmitted to the wheels through the couplings.Couplings connect the motor or gearbox to the drive wheels, transmitting mechanical energy efficiently.

Braking System:To stop and control the movement of the trolley, a braking system is essential. This may consist of electric or mechanical brakes that apply to the traveling wheels or the motor itself.The braking system is designed to hold the trolley in place when not in use and to decelerate it smoothly during operation.

2) Function of the trolley operating mechanism

The trolley traveling mechanism of an underhung bridge crane plays a critical role in the movement of the crane along the span of the bridge. It enables the crane to travel horizontally over the structure, allowing it to position itself precisely over different load areas.

 

6.Crane wheel

The crane wheel in such a setup serves as a critical component for the movement of the crane along the runway. These wheels are typically mounted on the end trucks (end carriages) of the crane bridge and have specific design characteristics for smooth operation.

Material: Usually made of high-strength steel or alloyed materials to endure heavy loads and resist wear.

Shape: May be flat, crowned, or tapered depending on the rail profile for optimal engagement and movement.

Mounting: The wheels are often mounted on axles attached to the crane's end trucks, and they are designed to accommodate small misalignments in the runway.

Load Distribution: The wheels are engineered to distribute the load evenly on the underhung system, reducing wear on the runway and crane components.

Adjustability: The wheels or their mountings may have adjustable features to align properly with the runway.

7.Crane Hook

The crane hook of an underhung bridge crane plays a pivotal role in lifting and handling loads. Typically made from forged alloy steel for high strength and durability. Features a curved or "C" shape, enabling secure attachment to slings, chains, or lifting devices.

Types:Single Hook: Used for lighter loads. Double Hook: Suitable for heavy and balanced loads.Safety Features:Safety latch to prevent accidental disengagement of the load.Swivel mechanism for smooth rotation, minimizing rope or chain twisting.

The hook is attached to a hoist mechanism via:A wire rope or chain for lifting.A pulley system for mechanical advantage.The hoist trolley runs along the bottom flange of the underhung crane's girder, distributing weight efficiently.

Motor

The motor of an underhung bridge crane plays a crucial role in driving the crane's movement and enabling it to lift and transport loads efficiently.

Purpose

Hoisting Motor: Powers the lifting mechanism, enabling vertical movement of loads.

Trolley Motor: Drives the trolley that moves the hoist along the bridge.

Bridge Motor: Drives the movement of the entire crane along its runway.

Key Features

Power and Torque: Sufficient to handle the rated load of the crane.

Duty Cycle: Rated for intermittent or continuous operation based on the crane's application.

Safety: Equipped with features like braking systems to hold loads in place.

Durability: Designed to withstand demanding industrial environments.

Additional Considerations

Environmental Conditions: Motors should be protected against dust, moisture, and temperature extremes.

Energy Efficiency: Opt for high-efficiency motors to reduce energy consumption.

Maintenance: Ease of access for regular inspection and repair..

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Sound and light alarm system & limit switch

1) Sound and light alarm system

A sound and light alarm system for an underhung bridge crane is an important safety feature that enhances operational awareness and reduces the risk of accidents.

Audible Alarms (Sound):

Types: Buzzers, sirens, or speakers.

Sound Levels: Typically between 85–120 dB to ensure audibility in noisy environments.

Features:Continuous or intermittent tones.Programmable sound patterns for different warning levels.Volume control to match the environment.

Visual Alarms (Light):

Types: Flashing LED lights, strobe lights, or beacon lamps.

Red: Danger or immediate attention.

Yellow/Amber: Caution or pre-warning.

Green: Safe conditions (optional).

Features:High-intensity illumination for visibility.Rotating or pulsing light patterns.Weatherproof and durable casings for industrial environments.

Limit switch.

A limit switch is a critical safety and operational device installed in underhung bridge cranes (or overhead cranes). It is used to control and limit the motion of the crane or hoist, ensuring safe operation and preventing over-travel or potential collisions.

Functions: Stops the hoist or crane when it reaches the end of its allowable travel range, either horizontally along the bridge or vertically with the hoist. Protects the crane and surrounding structures from damage caused by overextension. Limits the travel to specific zones in the workspace to enhance precision and safety.

Types:Rotary Limit Switch:Installed on the hoist mechanism.Works by measuring the number of revolutions of the drum or motor shaft to control the vertical movement of the hoist.Lever/Plunger-Type Limit Switch:Activated mechanically by physical contact with a moving part (like the crane trolley or bridge).Typically used for horizontal motion limits.Magnetic Limit Switch:Uses magnetic sensors to detect positions without physical contact.Highly reliable in environments where dirt or wear could affect mechanical switches.Proximity Limit Switch:Detects objects or positions without contact, using infrared, ultrasonic, or electromagnetic signals.Common in modern cranes for precise, non-contact detection.

 

10.Safety Devices

Overload Protection System : Load Cells or Overload Limiters: Monitors the load being lifted and stops operation if it exceeds the crane's rated capacity.Limit Switches Function: Protects the crane from moving beyond its safe operating limits.

Anti-Sway Mechanism Function: Sensors or proximity detectors to prevent collisions between multiple cranes on the same runway or between the crane and other obstacles.

Emergency Stop Button Function: Located on the control pendant, operator's cabin, or remote control. Instantly halts all crane movements during emergencies.

Infrared or Laser Sensors Function: Built-in sensors for monitoring wear, deformation, or malfunction in critical components.

Load Swing Control: Advanced cranes may include anti-sway technology to minimize load swing during operation, ensuring stability and safety.

 

11.Control Mode

Manual Control (Pendant Control) Description: The crane is operated manually, typically via a pendant control box or a handheld remote.The operator is in close proximity to the crane.Used for simple, low-capacity cranes.

Semi-Automatic Control: Certain functions (like movement along the bridge or hoisting) are automated, while others require manual input.Combines human operation with automated assistance.Increases efficiency for repetitive tasks.Often used in workflows with consistent load patterns.

Fully Automatic Control: The crane operates autonomously, executing pre-programmed tasks without real-time manual intervention.Utilizes sensors, programmable logic controllers (PLCs), or computerized systems.

Sketch

 

 

Main technical

 

 

 

Space Efficiency: The underhung design requires less headroom compared to top-running cranes, making it ideal for facilities with low ceilings.These cranes can be mounted on the building's roof or ceiling structure, eliminating the need for additional supporting columns.

Flexibility in Installation: Underhung cranes can operate on curved tracks, offering greater flexibility in layout for complex workflows.They can be installed in tight or constrained spaces where other crane types might not fit.

Cost-Effectiveness: Since they don't require standalone columns, installation costs can be lower.Underslung cranes are generally lighter than top-running cranes, reducing the structural load on the building.

Enhanced Accessibility: These cranes are suitable for applications requiring crane coverage close to walls or other obstructions.The design allows for access to locations not reachable by other types of cranes.

Improved Safety: The crane's underhung position can contribute to stability in certain applications.Minimizes the risk of collisions in confined spaces.

Versatile Applications：Frequently used in manufacturing plants, assembly lines, and warehouses.Can support lighter loads efficiently while adapting to various facility layouts.With simpler construction and direct accessibility, maintenance and inspection are generally more straightforward.

 

 

Small Workspaces：Used in facilities with limited headroom or confined spaces where traditional top-running cranes cannot be installed.

Light to Moderate Lifting：Typically used for lighter loads (commonly 1–10 tons) in manufacturing, assembly, or maintenance processes.

Complex Workstations：Ideal for production lines or assembly areas requiring precision movement and frequent, smaller load handling.

Transportation Between Work Areas：Suitable for moving materials across multiple workstations within a single bay or building.

Indoor Warehouses：Common in warehouses or factories with pre-existing ceilings, where the crane runway beams can be directly attached.

 

 

Design and Engineering: Understand the customer's needs, such as load capacity, span, lift height, operating environment, and any specific features. Create detailed CAD drawings of the crane structure, including the main girder, end carriages, and support systems.Develop the electrical system (motors, controllers, wiring) and mechanical components (hoist, trolley, and drive mechanisms). Ensure the design meets applicable standards (e.g., ASME, ISO, or regional standards).

Material Procurement: Order high-grade steel for the main girder, end carriages, and support structures.Procure motors, control panels, and wiring systems.Acquire gears, wheels, hoists, and other essential components.

Fabrication of Components:Steel plates and profiles are cut to precise dimensions.Weld the steel components to form the girder and end carriages.Machine critical areas for proper alignment and fit of parts. Sandblasting or shot blasting is performed, followed by painting or galvanizing for corrosion protection.Assemble the hoisting mechanism and trolley component.Pre-assemble components like the main girder, end carriages, and trolley in sections.Fit the trolley onto the main girder and attach the end carriages.Install and connect motors, control systems, and wiring for the electrical system.

Quality Inspection: Verify dimensions and alignment of all components.Perform load tests with weights to check structural integrity and functionality.Ensure all electrical systems operate correctly, including emergency stops and limit switches.Test the crane's movement along the runway and hoist operations.

Disassembly and Packaging (if required):For transportation, the crane may be partially disassembled and packaged securely for shipment to the installation site.

Installation and Commissioning: Assemble the crane at the installation site, including mounting on the runway beams.Ensure the crane runs smoothly on the tracks or runway.Re-test load capacity, electrical systems, and operational controls on-site. Provide operational and safety training for the end users.

Handover and Maintenance:Handover the completed crane with all relevant documentation, including test certificates, maintenance schedules, and operating manuals.Offer after-sales support, such as regular maintenance and spare parts supply.

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%.