Grab Bucket Crane

 

 

A Grab Bucket Crane is a specialized lifting machine equipped with a grab bucket for handling bulk materials like sand, coal, gravel, grain, and scrap metal. These cranes are widely used in ports, warehouses, power plants, and industrial sites to facilitate efficient loading and unloading operations.

Key Features
✅ High Efficiency – Designed for fast and continuous material handling.
✅ Durable Grab Bucket – Built with high-strength steel for long service life.
✅ Automated Control – Available with remote control and automation options.
✅ Customizable Design – Various grab types (mechanical, hydraulic, or electro-hydraulic) to suit different materials.
✅ Safety & Reliability – Equipped with overload protection and safety systems.

 

Warranty：2 Years

Weight (KG)：5000 kg

Feature：Bridge Crane

Condition：New

Span：10.5~31.5m

Trolley travelling：40-50m/min

Lifting height：12m 16m 30m

Working System：A7-A8

Power Source：3 Phase 380V 50hz

 

 

1.Main beam

The girder of a grab crane is the main horizontal structural component that supports the hoisting mechanism and the grab bucket. It plays a vital role in ensuring the stability, strength and load-bearing capacity of the crane.
The girder of a grab crane is usually made of high-strength steel to withstand heavy loads. It can be a box-type girder or a truss-type girder, depending on the application.
The girder distributes the weight of the grab bucket and the lifted material over the crane structure. It is designed to handle dynamic loads, as grab bucket operations involve frequent opening and closing movements.

Lifting System

The lifting system of a grab bucket crane is designed to control the movement of the grab bucket, allowing it to open, close, lift, and lower materials efficiently. It typically consists of the following key components:
1. Hoisting Mechanism
The hoist motor provides power for lifting and lowering the grab bucket.
A drum or winch is used to wind the wire ropes that support the grab bucket.
The lifting system usually has two sets of wire ropes:
Lifting ropes: Raise and lower the grab bucket.
Closing ropes: Control the opening and closing of the grab bucket.
2. Wire Rope System
The wire ropes are responsible for the grab bucket's movement.
The lifting rope lifts and holds the bucket in place.
The closing rope pulls the bucket's jaws together to grip the material.
3. Grab Bucket
A mechanical or hydraulic grab bucket is attached to the hoisting system.
It consists of two or more jaws that open and close to grab materials.
Types of grab buckets:
Mechanical grab: Operated by the lifting system's wire ropes.
Hydraulic grab: Uses hydraulic cylinders for opening and closing.
4. Pulley System
The system includes a series of pulleys (sheaves) to guide the wire ropes.
Reduces the effort required to lift and control the grab bucket.
5. Electrical or Hydraulic Control System
Controls the hoist motor, wire ropes, and grab bucket movements.
Modern cranes use PLC (Programmable Logic Controllers) for precise operation.
6. Crane Structure & Trolley
The lifting system is mounted on a bridge crane, gantry crane, or jib crane.

3.End carriage

The end carriage of a grab bucket crane is a critical component that supports and moves the entire crane structure along the runway rails. It is responsible for the stability, mobility, and alignment of the crane system. Here's a breakdown of its key aspects:
1. Function & Importance
Supports the bridge girder and allows the crane to move along the runway rails.
Houses the wheel assembly, which consists of drive wheels and idler wheels for motion.
Ensures smooth and precise movement, reducing structural stress and enhancing efficiency.
2. Main Components
Wheel Assemblies: Includes drive wheels (connected to motors) and idler wheels (free-rotating).
Motors & Gearboxes: Provides the driving force for movement.
Bearings & Axles: Helps reduce friction and wear.
Bumpers & Buffers: Prevents excessive impact during movement.
Frame Structure: Usually made of high-strength steel for durability.
3. Types of End Carriages
Single-Drive End Carriage: One side has a motor, the other side has idler wheels.
Double-Drive End Carriage: Both sides are motor-driven for enhanced stability and load capacity.

 

 

4.Crane travelling mechanism

1) The crane running mechanism is mainly composed of a drive unit, a transmission shaft, wheels and a braking system. These components work together to enable the crane to move smoothly laterally on the laid track, thereby expanding the operating range and improving the efficiency and flexibility of material handling.

2) The drive unit usually uses a motor with a reducer to transmit power to the wheels through the transmission shaft to drive the entire crane to move along the track. This design not only ensures sufficient driving force, but also controls the movement speed of the crane by adjusting the speed of the motor.

3) The design of the crane running mechanism focuses on high efficiency and stability, which can ensure the safety of operation while ensuring rapid movement. For example, the use of advanced three-in-one drive technology, that is, the integrated design of the drive unit, transmission device and braking system, not only simplifies the structure, but also improves the response speed and reliability.

4) Modern crane running mechanisms are equipped with intelligent control systems such as PLC and frequency converters, which can accurately control the start, operation and stop of the crane, and automatically adjust when necessary to adapt to different operating conditions and environmental requirements.

 

5.Trolley travelling mechanism

Main Components
Trolley Frame – A rigid structure that houses the traveling and lifting mechanisms.
Traveling Wheels – Mounted on the trolley frame and move along rails installed on the bridge girder.
Motors & Gear Reducers – Provide power to drive the trolley movement.
Brakes – Ensure controlled stopping and prevent unwanted movement.
Couplings & Drive Shafts – Transmit power from the motor to the wheels.
Rail Tracks – Guide the trolley movement along the bridge girder.
Limit Switches & Buffers – Prevent excessive travel and ensure safe operation.

Working Principle
The crane receives electrical power through a conductor bar or cable reel system.When the operator engages the control panel, the electric motor starts, driving the gear reduction system.Speed control is achieved through variable frequency drives (VFD) or traditional motor controllers.Directional movement is controlled via the operator's panel.When the travel function is disengaged, the braking system stops the crane smoothly.Buffers absorb any excess motion at the rail ends.

 

6.Crane wheel

A crane wheel of a grab bucket crane is a crucial component that enables the crane to move along its designated path, typically on rails. These wheels are designed to support heavy loads and ensure smooth operation, even under tough working conditions.
Key Features of Crane Wheels in Grab Bucket Cranes
Material: Made from high-strength forged or cast steel, such as 42CrMo or 65Mn, to withstand high stress and wear.
Heat Treatment: Induction-hardened for improved durability and resistance to wear.
Load Capacity: Engineered to handle the heavy dynamic and static loads imposed by the grab bucket's operation.
Rail Compatibility: Precisely machined to match the rail dimensions and reduce rolling resistance.
Flange Design: Some wheels have single or double flanges to maintain alignment on the track, preventing derailment.

7.Crane Hook -Crane With Grab

1) Hook structure: The hook is usually made of high-strength steel and is designed to withstand heavy loads while having a certain degree of elasticity and toughness to prevent breakage when overloaded.

2) Motor drive: The crane's motor drives the drum through a reducer, and the wire rope wound on the drum is connected to the hook. The start and stop of the motor controls the lifting and lowering of the hook.

3) Grab bucket connection: The hook is connected to the grab bucket, and the grab bucket opens and closes under the control of the motor under the guidance of the hook. When the grab bucket is clamping materials, the lifting and lowering of the hook can lift the grab bucket to the required height.

4) Control system: The control system equipped with the crane (usually remote control or control room control) can accurately control the movement of the hook to ensure the safety and efficiency of grabbing and releasing materials.

Safety device: To prevent accidental falling, the hook is usually equipped with a safety lock to ensure that the grab bucket does not accidentally fall off during operation.

Motor

1) Type: Three-phase asynchronous motors are usually used because of their simple structure, high reliability and suitability for long-term operation.

2) Power selection: The power of the motor is determined according to the design load and frequency of use of the crane to ensure smooth operation under full load.

3) Drive mode: The motor is connected to the drum through a reducer, which converts the high-speed rotation of the motor into a low-speed, high-torque rotation to lift the hook and grab.

4) Control system: Modern crane motors are usually equipped with frequency converters, which allow precise control of the motor speed, achieve smooth lifting and lowering, and reduce impact loads.

5) Heat dissipation and protection: The motor is usually equipped with heat dissipation devices and overload protection functions to prevent damage caused by overheating and overloading.

Maintenance: Regularly check the insulation, lubricating oil and cooling system of the motor to ensure that it operates in optimal conditions.

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Sound and light alarm system & limit switch

1) Sound and light alarm system
Purpose: Enhances safety by providing audible and visual warnings to operators and workers in the surrounding area.
Functions:
Alerts workers when the crane is in operation.
Signals when the grab bucket is opening or closing.
Warns in case of overload, faults, or emergency situations.
Helps prevent collisions and accidents in busy industrial environments.

2) Limit switch

Types of Limit Switches:
Hoisting limit switch: Stops the hoist when the grab bucket reaches its highest or lowest point.
Trolley limit switch: Prevents the trolley from exceeding its travel limits on the beam.
Bridge limit switch: Stops the crane from moving beyond the set boundaries on the runway.
Grab bucket open/close limit switch: Ensures the grab bucket does not exceed its mechanical limit when opening or closing.
Benefits:
Prevents mechanical damage due to over-travel.
Enhances safety by avoiding unexpected movements.
Ensures precision control over the grab bucket.

10.Safety Devices

1. Overload Protection
Load limiters are installed to prevent the crane from lifting more than its rated capacity, which could cause structural damage or failure.
Load cell systems continuously monitor the weight being lifted and can trigger alarms or stop the crane if an overload is detected.
2. Emergency Stop Button
An emergency stop button is usually placed at multiple locations on the crane for quick shutdown in case of an emergency.
3. Anti-Collision System
This system ensures that the crane doesn't collide with other objects or structures during operation. It can include sensors, cameras, or radar systems that monitor the surrounding area.
4. Overwind and Overtravel Protection
Overwind protection ensures that the crane's hoisting mechanism doesn't exceed its maximum lifting height, preventing damage to the crane or the load.
Overtravel protection prevents the crane from moving beyond its travel limits, either horizontally or vertically.
5. Emergency Power Supply
Some cranes are equipped with an emergency power system, which allows the crane to function for a short period even if the main power source fails, providing time to safely lower the load.
6. Crane Speed Limiters
These devices restrict the speed of the crane's movement to safe levels, preventing sudden movements that could lead to accidents.

11.Control Mode

1. Manual Control Mode
In this mode, the operator controls the crane using a traditional joystick or push-button control. The operator manually commands the movement of the crane's arm, winches, and grab bucket, typically via a control panel or a radio remote controller.
2. Semi-Automatic Mode
In this mode, the crane operates with some level of automation, but the operator still needs to monitor and intervene when necessary. For example, the operator may control certain movements of the crane while the system automatically adjusts others (like grabbing or releasing materials). This mode can increase efficiency but still allows for human oversight.
3. Automatic Control Mode
The crane is fully automated in this mode. Using advanced sensors, cameras, or pre-set programming, the crane can perform tasks such as grabbing, lifting, and dumping without direct operator input. The crane typically operates based on pre-programmed logic or commands, allowing it to complete repetitive tasks autonomously with minimal human intervention.
4. Remote Control Mode
Some modern cranes offer remote control via wireless communication, allowing the operator to control the crane from a distance. This can be particularly useful in dangerous or hard-to-reach areas, improving safety and flexibility.
5. Distributed Control System (DCS) Mode
This mode involves a more advanced control system where different components of the crane (motors, sensors, etc.) communicate with each other via a central control unit. The system can optimize the crane's movements for better efficiency and smoother operation.
6. Load-Sensing or Adaptive Mode
Some cranes feature load-sensing systems that adjust the crane's movements based on the weight or type of material being handled. This mode allows for more precise and efficient control when handling different types of cargo, such as bulk materials or containers.

12.Sketch-Crane With Grab

Main technical-Crane With Grab

 

 

• Efficient Material Handling: The grab bucket is specifically designed to handle loose, bulk materials. It can efficiently pick up, transport, and unload materials, reducing the need for manual labor or other equipment.
• High Load Capacity: Grab bucket cranes can handle heavy and large volumes of material in a single operation. This makes them ideal for industries such as shipping, construction, and mining.
• Versatility: They are highly versatile, capable of working with a wide range of materials, including dry bulk, scrap, sand, and gravel. The bucket can be easily adapted to different types of cargo.
• Cost-Effective: Using a grab bucket crane can reduce operational costs compared to other material handling methods, as it requires less manpower and is faster than traditional loading/unloading methods.
• Durability: These cranes are built to withstand harsh working conditions. They are typically made of high-strength materials to handle the heavy loads and rough environments they operate in.
• Reduced Spillage: The design of the grab bucket minimizes material loss during loading and unloading, which is especially important when dealing with valuable or hazardous materials.
• Flexible Operation: Grab bucket cranes can be used in a variety of settings, including ports, construction sites, warehouses, and factories, offering a wide range of applications.
• Safety: These cranes are equipped with safety features such as overload protection, which helps prevent accidents and ensure the safe handling of materials.

 

 

• Port Operations: Grab bucket cranes are often used at docks and harbors to load and unload bulk materials from ships. They can handle various types of cargo, such as coal, iron ore, grain, or containers of loose materials.
• Construction and Demolition: In construction sites, they can be used for lifting and moving materials like sand, gravel, and debris. They can also help with clearing rubble during demolition projects.
• Mining: Grab bucket cranes are used in mining operations to move large quantities of mined ore or waste materials. They help in loading and unloading from mining trucks and storage areas.
• Waste Management: In recycling or waste handling operations, grab bucket cranes are used for moving heavy and bulk waste materials, like scrap metal, waste plastic, or other recyclable materials.
• Power Plants: For handling materials like coal or ash in power plants, grab bucket cranes can be used to move fuel or waste material to and from storage and disposal areas.
• Steel Mills and Scrap Yards: Grab bucket cranes are also used in steel mills or scrap yards for loading and unloading scrap metal, scrap steel, or ingots.

 

 

1. Design and Engineering
Initial Design: Engineers develop detailed technical drawings based on customer requirements, including the capacity, type of grab bucket (e.g., hydraulic, electric), and specific crane features.
Material Selection: High-strength steel is often used for the main structural components, such as the boom, gantry, and tower. The grab bucket itself may be made from hardened steel to withstand wear and tear.
2. Fabrication of Major Components
Main Frame Construction: The main frame of the crane is fabricated by cutting, welding, and assembling steel plates. The structure must be both strong and lightweight to support heavy loads while ensuring efficient operation.
Boom Fabrication: The boom (the arm that extends from the crane to grab and move materials) is fabricated and tested for strength. It typically involves welding large beams of steel and attaching hydraulic cylinders for boom elevation and movement.
Gantry Fabrication: This includes the assembly of the gantry (a framework that supports the crane's operation on a rail system) and includes the installation of wheels or rails for horizontal movement.
3. Grab Bucket Manufacturing
Bucket Frame: The frame of the grab bucket is made from steel, welded into a structure designed to handle heavy loads.
Clamshell Mechanism: The grab bucket typically uses a clamshell mechanism, which requires careful design to ensure the opening and closing of the bucket is reliable. This involves hydraulic cylinders or electric motors depending on the crane type.
Bucket Testing: Grab buckets undergo quality control tests to ensure they can withstand wear and load demands without failure.
4. Assembly of Crane System
Assembly of Boom and Gantry: The boom, gantry, and other structural components are assembled at the workshop. This process includes welding, bolting, and ensuring alignment of moving parts.
Installation of Hoisting and Drive Mechanism: The hoisting system (including wire ropes, drums, and hoists) is installed along with the drive mechanisms. The power system may be hydraulic or electric.
Electrical and Hydraulic Systems: Wiring for control systems, power supply, and safety devices are integrated. Hydraulic lines are connected to the grab bucket for opening/closing operations.
5. Testing and Calibration
Load Testing: The crane is tested for load-bearing capacity, ensuring that it can handle the maximum rated weight of materials.
Hydraulic and Electrical Testing: The hydraulic and electrical systems are tested to ensure they function properly, including the grab bucket's opening and closing movements.
Control System Testing: The control system (operator controls, emergency stop, etc.) is tested for accuracy and responsiveness.
6. Final Inspection and Quality Control
Inspection: The crane undergoes a thorough inspection for safety and structural integrity. All welding, joints, and components are checked to ensure they meet safety standards.
Safety Features Check: This includes testing of safety systems such as overload protection, limit switches, and emergency shutdown mechanisms.
7. Painting and Coating
Surface Preparation: After assembly, the crane is cleaned and surface-treated to prevent corrosion.
Painting: A protective coating (usually epoxy or polyurethane) is applied to prevent rusting, especially for cranes that will be used in harsh environments like ports or industrial sites.
8. Shipping and Installation
Disassembly for Shipping: If necessary, parts of the crane are disassembled for easier transport.
Delivery and Assembly at Site: The crane is delivered to the customer site, where final assembly and installation are completed. This may include setting up the crane on rails or a specific foundation.

 

 

 

 

 

 

 

Material Inspection

Quality Inspection: Strict quality inspection is carried out on the purchased raw materials to ensure that they meet the design requirements and national standards.

Material Storage: Qualified materials are stored according to classification to prevent corrosion or damage.

Cutting and Forming

Steel Cutting: Use plasma cutting, laser cutting or flame cutting and other technologies to cut the steel according to the size of the design drawing.

Forming Processing: Form the steel plate through bending, rolling, welding and other processes to manufacture the main beam, end beam and other structural parts.

Welding

Component Welding: The cut and formed steel parts are welded into the main structures such as the main beam, end beam and trolley. The welding process needs to be strictly controlled to ensure the structural strength and welding quality.

Weld Inspection: Use non-destructive testing technology (such as ultrasonic testing, radiographic testing) to inspect the welds to ensure that there are no cracks or other defects.

Machining

Precision Machining: Precision machining is performed on the key components of the crane, such as wheel sets, bearing seats, pulleys, etc., to ensure their dimensional accuracy and surface quality.

Assembly of the whole machine

General assembly: On the basis of pre-assembly, the overall assembly of the crane is carried out, including the final installation of the main beam, end beam, lifting mechanism, walking mechanism, etc.

Commissioning and testing

Under dynamic conditions, the operating performance of the crane is tested, including the testing of lifting, walking, steering and other functions. The overall size of the assembled bridge crane is checked to ensure that all dimensions meet the design requirements.

Spraying and anti-corrosion treatment

Surface treatment Rust removal: Rust removal on the surface of the crane, common methods include sandblasting, pickling, etc. Primer spraying: Spray anti-corrosion primer on the treated surface to prevent metal oxidation and corrosion. Topcoat spraying Color spraying: Spray topcoat according to customer requirements or industry standards to give the crane a protective and decorative effect. Marking: After spraying, mark the crane's identification information in accordance with the specifications, such as model, rated load, etc.

Factory and installation

Packaging and transportation

Packaging protection: Protectively package the key components of the crane to prevent damage during transportation. Transportation arrangement: According to the equipment size and transportation conditions, select a suitable transportation method to transport the crane to the customer's site.

Acceptance and delivery

Customer acceptance

On-site acceptance: The customer conducts on-site acceptance of the crane according to the contract requirements and technical specifications to check the performance and quality of the equipment.

Problem rectification: If any problems are found, the manufacturer needs to rectify them in time to ensure that the equipment fully meets the customer's requirements. Delivery and use Operation training: The manufacturer usually trains the customer's operators to ensure that they can operate the crane correctly and safely.

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