20 T Double Girder Goliath Gantry Crane

The 20 Ton Double Girder Goliath Gantry Crane is a robust and highly efficient lifting solution engineered for heavy-duty material handling applications. Designed with precision and built for durability, this crane system is ideal for outdoor environments such as shipyards, construction sites, heavy fabrication industries, and logistics yards.
Featuring a double girder structure, this crane offers superior load distribution and increased lifting capacity compared to single girder alternatives. The design ensures enhanced stability and safety during high-capacity lifting operations, making it a reliable choice for handling heavy and oversized loads.
The gantry frame, commonly referred to as a "Goliath" structure, is supported by sturdy legs running on ground-level rails or wheels, eliminating the need for overhead runway beams. This allows the crane to be deployed in open spaces or areas where overhead cranes are not feasible.

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

Place of Origin：Henan, China

Warranty：2 years

Weight (KG)：50000 kg

Video outgoing-inspection：Provided

Machinery Test Report：Provided

Application：Outdoor

Keywords：Gantry Crane

Rated Loading Capacity：50Ton

Cross travelling speed：44.6m/min

Long travelling speed：47.1m/min

Control way：cabin

Power supply：Cable reel

Steel track：QU80

Power：3-phase AC 50HZ 380V

1.Main beam

1)Structure:
The main beam consists of two parallel girders, which are designed to handle the weight of the crane and the load.
These girders are connected by cross beams to form the crane's framework, creating a rigid structure.
It is typically made from high-strength steel to ensure durability and the ability to withstand heavy loads.
2)Design:
The design of the main beam ensures that the load is evenly distributed across the structure, minimizing stress points.
It often incorporates welded steel plates and structural supports, including bracing elements for stability.

2.Lifting System

1)Trolley System
The trolley moves along the length of the crane's beams, carrying the hoist unit across the span. The trolley typically travels on rails mounted on the top of the two main girders.
For a double girder gantry crane, the trolley system is designed to ensure smooth and precise movement, which is essential for accurate positioning of heavy loads.
2)Lifting Mechanism (Wire Rope or Chain)
A wire rope or chain is used to lift the load from the ground to the desired height.
The rope or chain runs through the hoist system and is wound or unwound by the drum, providing the vertical lift.
The type of rope or chain used depends on the crane's application and the load being lifted. For a 20-ton crane, wire rope is typically used due to its strength and durability.
3)Drive and Control System
The hoist and trolley are powered by electric motors, with independent drives for each system (hoist, trolley, and sometimes even the gantry movement).
Control systems include pendant controllers or wireless remote controls, allowing the operator to control the lifting operation, trolley movement, and sometimes the gantry's movement.
Some gantry cranes also incorporate advanced frequency inverters for smoother operation and better load handling by adjusting the speed and acceleration of the hoist and trolley.
4)Brake System
Brakes are a vital safety feature of the lifting system. They are used to hold the load in position when the crane is stationary or during the lowering process.
The brake system is typically integrated into the hoist motor and may include electromagnetic brakes or mechanical brakes, depending on the design.
5)Load Limiters and Safety Features
To ensure safe lifting, load limiters are installed to prevent the crane from lifting loads that exceed its rated capacity (20 tons in this case).
Additional safety features include overload protection, emergency stop systems, and anti-sway systems to minimize load movement during lifting.

3.End carriage

1)Function of the End Carriage
The end carriage is essentially the base frame of the gantry crane that carries the entire load-bearing structure, including the girders (main beams) and the hoisting mechanism.
It provides the traveling mechanism for the crane, allowing it to move along the rails or tracks on the ground, either across the worksite or within a specified operational area.
2)Design and Structure
The end carriage typically consists of two main structures, one at each end of the crane's gantry. These structures are designed to support the weight of the entire crane while maintaining stability during operation.
The end carriage frame is typically made from welded steel and reinforced with additional bracing for structural integrity, ensuring it can handle the stresses imposed by the crane's lifting and moving operations.

4.Crane travelling mechanism

1)End Carriages
The end carriages are the main structural components that house the travelling mechanism. There are typically two end carriages, one at each end of the crane. These carriages support the entire crane structure, including the double girder system, and house the wheels, motors, and drive systems that enable the crane to move.
2)Wheels and Axles
The wheels of the end carriages are crucial for the crane's travel. These wheels are typically made from high-strength steel and are mounted on axles, which are part of the end carriage structure.
3)Drive Motors
The crane's travelling mechanism is powered by electric motors mounted on the end carriages. Each end carriage typically has a drive motor (or two motors, one on each end carriage), which drives the wheels and enables the crane to travel along the track.
4)Transmission System
The electric motors are coupled with a transmission system that transmits power to the wheels. This system typically includes gears and clutch mechanisms that allow for efficient power transfer and controlled movement.
5)Control System
The travelling mechanism is controlled via the crane's control system. The operator can use a pendant control or wireless remote to control the movement of the crane.
6)Braking System
A critical safety feature of the travelling mechanism is the braking system. The brakes are used to stop the crane from moving when necessary and ensure safe, controlled movement.
7)Track System
The tracks on which the end carriages travel are an essential part of the travelling mechanism. The tracks are laid on the ground, either in a straight line or curved, depending on the layout of the workspace.

5.Trolley travelling mechanism

1)Trolley Design
The trolley is a mobile unit mounted on the double girder beams of the crane. It carries the hoist unit, which is responsible for lifting and lowering the load.
The trolley moves horizontally along the top of the two main girders (or beams), allowing the hoist to travel across the full span of the crane.
The trolley is supported by wheels or wheel assemblies, which run along the rail-like surface or track mounted on the top of the girder.
2)Wheels and Track System
The trolley's wheels are mounted on the top flange or rail of each girder, typically positioned on both sides of the girder beams for stability and to support the weight of the hoist and load.
Wheel assemblies are made from high-strength steel to bear the load without wear or deformation.
3)Drive System for Trolley Movement
The trolley's drive mechanism is typically powered by an electric motor that provides the necessary power to move the trolley along the girder beams.
4)Trolley Control System
The control system enables the operator to manage the movement of the trolley, including adjusting the speed and direction.

6.Crane wheel

1)Material: Typically made from forged steel or alloy steel with high tensile strength to handle heavy loads and resist wear.
2)Hardness: The wheel tread is usually hardened (heat-treated) to withstand continuous rolling and to reduce surface wear.
3)Type:
Flanged wheels: Prevent derailment by keeping the crane aligned on its rails.
Double-flanged or single-flanged: Depending on rail design and safety requirements.
Flat wheels (less common): Used if guided by external mechanisms.
4)Diameter:
Depends on the crane design, but for a 20-ton double girder goliath crane, wheel diameters generally range from 400 mm to 800 mm.
Bigger diameters are often used to reduce rolling resistance and wear.

7.Crane Hook

1)Type of Hook
Forged Steel Hook: Typically made from high-tensile forged alloy steel for strength and durability.
Single Hook or Ramshorn (Double) Hook:
For 20-ton capacity, single hooks are common.
Ramshorn (double hooks) are used for more balanced load distribution but are more typical in higher capacity cranes.
2)Safety Features
Safety latch: A spring-loaded latch to prevent the load from slipping off the hook.
Swivel mechanism: Allows the hook to rotate 360°, reducing the risk of twisting the hoisting wire rope or chain.
Overload indicator (optional): Some modern hooks integrate overload indicators or limiters.

8.Motor

1)Hoist/Lifting Motor
Capacity: 20 tons means the hoist motor needs to be quite powerful.
Power Rating: Typically ranges from 15 kW to 30 kW, depending on lifting speed and duty cycle.
Type: Squirrel cage induction motor or slip ring motor (more common in older designs).
Features: Often has variable frequency drive (VFD) for smooth speed control.
2)Cross Travel Motor (Trolley Motor)
Power Rating: Around 3 kW to 7.5 kW, depending on the speed and span.
Type: Standard squirrel cage induction motor.
Speed: Generally 20-30 m/min, but adjustable via VFD.
3)Long Travel Motor (Gantry Motor)
Power Rating: Can range from 5 kW to 15 kW per motor (usually two motors are used on each side).
Type: Again, squirrel cage induction motor is common.
Speed: Usually around 30-50 m/min, VFD-controlled for smooth acceleration/deceleration.
4)Motor Protection
All motors are typically protected with IP55 or higher enclosures for outdoor conditions.
Equipped with thermal protection (thermistors) and brake systems (especially for the hoist motor).

.

Sound and light alarm system & limit switch

1. Sound and Light Alarm System
Purpose:
To alert personnel nearby about crane operations such as hoisting, long travel, or emergency conditions.
Typical Features:
Audible Alarm:
Volume: 85 to 110 dB, adjustable depending on the environment.
Multi-tone siren (continuous, intermittent, or adjustable patterns).
Often includes different sound signals for travel, lifting, or emergencies.
Visual Alarm:
Rotating beacon or strobe light (LED or xenon type).
Colors: Most commonly red, yellow, or blue depending on site safety standards.
IP Rating: Generally IP65 or higher for outdoor use.
Voltage: Typically 24VDC, 48VDC, or 220VAC, matching your crane control system.
2. Limit Switches
Types Used in Goliath Gantry Cranes:
a) Hoisting Limit Switch (Lifting/Lowering Limit Switch)
Function: Prevents over-lifting and over-lowering of the hook block.
Type: Rotary geared type or lever type.
Stages: Often 2-stage, where:
1st stage reduces speed,
2nd stage stops the hoisting motion.
b) Long Travel Limit Switch
Function: Prevents the gantry from colliding with end stops on the runway.
Type: Lever-operated or roller plunger type.
Heavy-duty design with IP65/IP66 protection.
c) Cross Travel Limit Switch (Trolley limit switch)
Function: Limits the trolley's travel range on the bridge.
Type: Roller lever or cam type.
d) Anti-Collision Limit Switch (Optional for adjacent cranes)
Function: Detects nearby cranes to avoid collisions on the same runway.
Can be photoelectric sensor-based or proximity switches.

10.Safety Devices

1)Overload Limiter / Load Moment Indicator (LMI)
Function: Prevents lifting loads beyond the rated capacity (20 tons in this case).
2)Limit Switches
a) Hoisting Upper & Lower Limit Switch
Prevents over-hoisting or over-lowering of the hook block.
b) Long Travel Limit Switch
Stops the crane from colliding with runway end stops.
c) Cross Travel Limit Switch
Stops the trolley from exceeding its designated track on the girder.
d) Slewing or Anti-sway Limit (if applicable)
Limits rotational or swing motion depending on crane design.
3)Emergency Stop Switches
Function: Red mushroom-head buttons installed at control panels and pendant stations to immediately shut down the entire crane operation in case of emergencies.
4)Rail Clamp / Storm Brake
Function: Prevents crane movement during strong winds (outdoor use).
5)Anti-Collision System (for multiple cranes on the same runway)
Function: Prevents cranes from colliding with each other.
Type: Infrared sensor or ultrasonic sensor system with auto-stop feature.
6)Buffer / Bumper System
Function: Absorbs impact energy if the crane or trolley hits an end stop.
7)Sound and Light Alarm System
Function: Audible sirens + visual beacons (rotating or strobe lights) to alert nearby workers when the crane is moving or lifting.

11.Control Mode

1. Pendant Control (Wired Remote Control)
Description: A wired push-button pendant hanging from the crane or trolley.
Features:
Robust and cost-effective.
Operator must follow the crane while walking along the runway.
Includes hoist up/down, cross travel left/right, long travel forward/reverse, and emergency stop buttons.
Standard voltage: 48V or 24V control circuit for safety.
Application: Common in workshops or yards with straightforward operations.
2. Wireless Remote Control (Radio Remote Control)
Description: Handheld wireless control unit using RF (radio frequency) signals.
Features:
Increases operator mobility and safety by allowing the operator to stand at a safe distance.
Comes with an emergency stop button.
Typically includes dual-speed or stepless control (via proportional buttons) depending on the system.
IP65 or IP67 rated, designed for industrial environments.
Frequency: 433 MHz or 2.4 GHz (adjustable channels to avoid interference).
Application: Widely used in outdoor gantry crane operations or large manufacturing yards.
3. Cabin Control (Driver's Cabin)
Description: A fixed or traveling operator cabin mounted on the crane.
Features:
The cabin has joysticks, buttons, foot pedals, and HMI displays.
Often equipped with air conditioning, ergonomic seats, and full instrumentation.
Provides full control of hoist, trolley, and long travel movements.
Application: Used in heavy-duty or high-risk environments, e.g., steel plants, shipyards.
4. Control Panel Interface (PLC + VFD system)
Description: Modern cranes integrate PLC (Programmable Logic Controller) and VFD (Variable Frequency Drive) for automation and smooth speed control.
Features:
Allows integration with wireless or cabin controls.
Supports automatic positioning, anti-sway systems, and diagnostics.
Enables soft start/stop, overload protection, and remote monitoring.

12.Sketch

Main technical

1. High Load Capacity
Designed to handle heavy loads up to 20 tons or more with ease.
More robust compared to single girder cranes, making it ideal for heavy-duty applications.
2. Large Span & Coverage
Can achieve longer spans (wide rail-to-rail distance) and high lifting heights.
Covers large outdoor or indoor areas, making it perfect for shipyards, yards, and factories.
3. Independent Support Structure
Does not require building columns or roof structures like overhead cranes.
Operates on ground-mounted rails (runways), reducing building costs for new installations.
4. Versatile for Outdoor and Indoor Use
Can be used in open yards, ports, construction sites, and inside large workshops.
Suitable for harsh environments with proper weatherproofing (IP-rated components).
5. Dual Girder Strength & Stability
The double girder design provides increased stability, rigidity, and minimizes deflection under heavy loads.
Supports auxiliary hoists or maintenance platforms when needed.
6. High Operational Safety
Equipped with advanced safety devices: overload limiter, anti-collision system, limit switches, emergency brakes, etc.
Can integrate with automation features like anti-sway control or remote diagnostics via PLC/VFD systems.
7. Multiple Control Modes
Supports pendant control, wireless radio remote, or operator cabin control for flexibility.
Seamless switching between control modes enhances safety and efficiency.
8. Cost-Effective for Outdoor Heavy Lifting
More economical than building an entire overhead crane system, especially for outdoor heavy lifting projects.
Lower maintenance cost compared to tower cranes or mobile cranes in certain industries.
9. Customizable
Can be customized with special lifting attachments (e.g., spreader beams, magnets, C-hooks).
Available in explosion-proof, marine-grade, or high wind-resistant designs.

1. Shipyards & Marine Industry
Lifting and assembling ship blocks, engines, and large structural parts.
Handling heavy ship components like hull sections or machinery.
Outdoor gantry cranes are preferred due to their ability to cover large open areas.
2. Steel Plants & Foundries
Transporting heavy steel coils, ingots, billets, or molten metal ladles (when equipped with heat-resistant components).
Moving raw materials or semi-finished goods within the plant.
3. Construction Sites
Lifting precast concrete segments, steel beams, heavy formwork, and structural components.
Ideal for large infrastructure projects like bridges, metro stations, and power plants.
4. Rail Yards & Container Yards
Loading and unloading ISO containers, heavy machinery, or railcars.
Goliath cranes are often used in intermodal terminals or rail yards.
5. Wind Power & Heavy Equipment Manufacturing
Assembling wind turbine components like nacelles, hubs, or blades.
Handling large machinery or equipment during manufacturing processes.
6. Logistics & Warehousing (Outdoor Storage Yards)
Moving heavy goods in outdoor warehouses or bulk material yards (e.g., timber, stone blocks, large pipes).
Suitable where overhead cranes are impractical due to the lack of building structures.
7. Power Stations & Hydroelectric Projects
Used for turbine and generator installation.
Handling large equipment like transformers and hydro-mechanical parts.
8. Aerospace & Defense Sectors
Lifting aircraft components, defense equipment, or specialized tooling during assembly or testing.

1. Design & Engineering
Client requirements collection (capacity, span, lifting height, duty class).
Structural design of double girders, legs (portal frame), trolley, and hoisting system.
Finite Element Analysis (FEA) for structural integrity and load distribution.
Electrical system design (control panels, VFD, PLC, safety devices).
Final approval of drawings and BOM (Bill of Materials).
2. Raw Material Procurement
Sourcing of high-tensile structural steel (Q345B, Q355B, or equivalent).
Procurement of standard components (motors, gearboxes, brakes, bearings, electrical components, etc.).
Purchasing of special components (limit switches, alarms, rail clamps, etc.).
3. Steel Structure Fabrication
Cutting: CNC plasma or laser cutting of steel plates and profiles.
Beveling & Edge Preparation: For proper welding joints.
Welding:
Welding of double girders (box type or I-beam type).
Welding of gantry legs, end carriages, and trolley frames.
Use of automatic submerged arc welding (SAW) or MIG/MAG processes.
Non-Destructive Testing (NDT):
Ultrasonic testing (UT), Magnetic Particle Inspection (MPI) on welded seams.
Radiographic inspection for critical joints.
4. Machining & Finishing
Machining of wheels, trolley frames, drum shafts, and gearboxes as per tolerances.
Boring & Drilling of assembly holes (e.g., for rail tracks on girders and trolley beams).
Surface Grinding: For contact surfaces (e.g., trolley rail seats on girders).
5. Surface Treatment
Shot blasting of all fabricated steel structures to Sa2.5 standard.
Application of anti-corrosion primer and topcoat painting (e.g., epoxy or polyurethane paint).
Paint thickness typically 80-120 microns depending on site environment (marine, industrial, etc.).
6. Mechanical Assembly
Installation of wheels, end trucks, travel motors, gearboxes, and drive shafts on the gantry legs.
Assembly of trolley/hoist unit, including:
Wire rope drum, hook block, hoisting motor, reducer, brake.
Trolley traveling mechanism (cross travel motor, wheel groups).
Mounting of rail clamps or storm brakes (if outdoor use).
7. Electrical Assembly
Wiring of control panels (MCC and PLC).
Installation of limit switches, overload protection, and emergency stop buttons.
Fitting of cables, cable festoons, or energy chains for trolley power supply.
Integration of VFDs, soft starters, and remote-control systems.
8. Pre-Assembly & Testing in Workshop
Pre-assemble girder and leg structure to ensure accurate bolt alignment.
Function test of trolley travel, hoist, and long travel drive systems.
Testing of limit switches, alarms, emergency stops, and overload protection.
Trial operation using no-load or test loads (typically 25%-100% of rated capacity).
9. Disassembly & Packing
Disassemble into transportable sections (girders, legs, trolley unit, etc.).
Anti-corrosion treatment for mating surfaces.
Pack electrical components and motors in protective crates.
Label all parts for easy re-assembly at the installation site.
10. Delivery & Site Installation
Transport by flatbed trucks or containers.
On-site erection of gantry structure using mobile cranes.
Rail alignment, crane re-assembly, and final commissioning.
11. Load Testing & Commissioning
Conduct static load test (usually 125% of rated load).
Dynamic load test (with 100% load to verify functionality).
Adjustments to brake torque, limit switches, and VFD parameters.
12. Handover & Training
Final inspection with the client.
Provide operation manual, maintenance guide, and training to operators and maintenance staff.

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%.