• Feb 28, 2025
• News

What is a Clamshell Bucket Used for?

Clam-shell Buckets handles loading & unloading of industrial waste, grain, sand, rocks & so forth in addition to digging & dredging activities.

If you've ever been to a construction site, harbor, and dredging site, you've probably noticed buckets on cranes that look like giant metal jaws. If you're in construction, bulk material handling, dredging, or any industry that deals with moving loose materials, understanding the crane clamshell bucket is essential.

What is a Clamshell Bucket?

A clamshell bucket, also often referred to as a clamshell grab bucket or simply a grab bucket, is a specialized type of bucket or grab designed to be attached to a crane or other lifting equipment. What makes it distinctive is its operation: it uses two hinged jaws, resembling the two halves of a clamshell, to scoop, grab, and lift loose materials. Think of it as a giant, mechanized hand for your crane, capable of grabbing and moving bulk materials with surprising precision and efficiency.

Unlike a standard crane hook that requires pre-slung or packaged loads, a clamshell bucket is designed to directly engage with and pick up loose materials from stockpiles, hoppers, trucks, railcars, or even underwater. This self-loading and unloading capability is what makes clamshell buckets so incredibly versatile and valuable across a wide range of industries.

The Clamshell Mechanism: How Does it Grab?

The genius of a clamshell bucket lies in its simple yet effective operating mechanism. While specific designs vary, the basic principle remains the same:

• Hinged Jaws: The bucket consists of two main sections, the jaws or shells, which are hinged together at a pivot point. These jaws are what actually do the digging and grabbing. The clamshell bucket design centers around the efficient opening and closing of these jaws.
• Opening and Closing Mechanism: The jaws are opened and closed by a mechanism connected to the crane's hoist cable or hydraulic system. This mechanism can be:
  1. Cable Operated (Mechanical Clamshell): In mechanical clamshell buckets, cables or ropes are used to control the opening and closing of the jaws. Pulling on specific cables opens or closes the bucket via a system of levers and linkages. Mechanical clamshell buckets are often robust and reliable, suitable for heavy-duty applications.
  2. Hydraulic Operated (Hydraulic Clamshell): Hydraulic clamshell buckets utilize hydraulic cylinders to power the opening and closing of the jaws. Hydraulic operation provides powerful and precise control over the bucket's digging and grabbing action. Hydraulic clamshell buckets are popular for their efficiency and digging force.
  3. Electro-Hydraulic Operated (Electro-Hydraulic Clamshell): Electro-hydraulic clamshell buckets combine electric motors to power a hydraulic pump, which in turn actuates the hydraulic cylinders for jaw operation. Electro-hydraulic clamshell buckets offer the advantages of hydraulic power with electric operation, often preferred for cleaner and quieter operation compared to engine-driven hydraulic systems.
• Digging and Grabbing Action: To grab material, the crane lowers the open clamshell bucket onto the stockpile or material pile. The closing mechanism is then activated, causing the jaws to close and scoop up the material within the bucket. The crane then hoists the closed bucket, transports it to the desired location, and opens the jaws to discharge the material. This cycle can be repeated efficiently for continuous material handling.

Versatile Uses of Clamshell Buckets

The adaptability of clamshell buckets makes them invaluable across a wide range of industries and applications. Their ability to grab and lift loose materials directly, without pre-handling, makes them exceptionally efficient in many scenarios.

Bulk Material Handling

One of the primary clamshell bucket applications is in bulk material handling. They are ideal for efficiently moving large volumes of loose materials like:

• Aggregates (Gravel, Sand, Crushed Stone): Loading and unloading trucks, railcars, or barges with aggregates at quarries, construction sites, and concrete plants. Clamshell buckets for aggregates are common in construction material supply chains.
• Coal and Minerals: Handling coal at power plants, mines, and transloading facilities. Moving minerals and ores in mining and processing operations. Clamshell buckets for coal handling are essential in power generation and mining.
• Grains and Agricultural Products: Loading and unloading grains, fertilizers, and other agricultural bulk materials at ports, silos, and processing facilities. Clamshell buckets for grain handling improve efficiency in agricultural logistics.
• Scrap Metal and Recyclables: Sorting, loading, and unloading scrap metal at recycling yards and processing plants. Handling various recyclable materials in waste management facilities. Clamshell buckets for scrap metal are robust and efficient in recycling operations.
• Fertilizers and Chemicals: Handling bulk fertilizers, chemicals, and other industrial materials in manufacturing and processing plants.

In bulk material handling, crane clamshell buckets offer significant advantages over manual labor or less efficient methods like conveyors or loaders for certain applications. Their ability to quickly grab and discharge large volumes of material, combined with the reach and mobility of a crane, makes them a powerful tool for moving bulk goods.

Excavation and Dredging

Beyond surface material handling, clamshell buckets are also widely used for excavation and dredging tasks, particularly in situations where vertical digging or reaching into confined spaces is required:

• Vertical Excavation: Digging pits, shafts, trenches, and foundations, especially in urban construction sites or areas with limited horizontal space where excavators or loaders are difficult to maneuver. Clamshell buckets for excavation are valuable in tight urban environments.
• Deep Excavation: Reaching deep below ground level for excavation of basements, underground utilities, or deep foundations. The vertical reach of a crane combined with a clamshell bucket allows for excavation at significant depths.
• Dredging and Underwater Excavation: Clamshell buckets for dredging are specifically designed for underwater excavation of sediment, silt, and debris from harbors, waterways, canals, and ponds. Dredging clamshell buckets are often heavier and more robust to withstand underwater conditions and denser materials.
• Caisson and Shaft Sinking: Excavating inside caissons or shafts during foundation construction or underground infrastructure projects. Clamshell buckets are ideal for removing excavated material from within confined vertical shafts.

In excavation and dredging, crane clamshell buckets excel in situations requiring precise vertical digging, reaching into deep or confined areas, and handling materials underwater. They complement other excavation equipment like excavators and backhoes, offering unique capabilities for specific digging tasks.

Other Specialized Applications

In addition to the common applications listed above, clamshell buckets can be used in many different specialized applications.

• Demolition: Controlled demolition of structures by selectively grabbing and removing sections of buildings or concrete structures. Clamshell buckets for demolition offer precision and controlled removal of materials.
• Foundry Operations: Handling foundry sand, molding materials, and removing slag or debris from furnaces or casting areas. Clamshell buckets for foundries are designed for high-temperature environments and abrasive materials.
• Waste Management and Recycling: Sorting and handling waste materials, bulky items, and construction debris at waste transfer stations and recycling facilities. Clamshell buckets for waste handling improve efficiency in waste processing.
• Environmental Remediation: Removing contaminated soil, sediment, or hazardous materials from environmental cleanup sites. Clamshell buckets for environmental remediation can be designed for specialized containment and handling of sensitive materials.

Advantages of Clamshell Buckets: Efficiency, Precision, and Versatility

Why choose a clamshell bucket over other crane attachments or material handling methods? They offer a set of advantages that make them the preferred choice for many applications:

• Self-Loading and Unloading: Clamshell buckets can directly scoop, grab, and load loose materials without requiring manual shoveling or pre-handling. This self-loading capability significantly reduces labor costs and speeds up material handling cycles.
• Vertical Digging Capability: They excel at vertical excavation and digging, reaching depths and confined spaces that other equipment cannot easily access. Vertical excavation with clamshell buckets is a key advantage in urban construction and deep digging projects.
• Precise Material Handling: Operators can control the opening and closing of the jaws to grab specific amounts of material and place them accurately, reducing spillage and waste. Precise clamshell bucket control enhances material utilization and minimizes cleanup.
• Versatility in Material Types: Clamshell buckets can handle a wide range of loose bulk materials, from fine sand and grains to heavy aggregates, scrap metal, and even underwater sediments. Their adaptability to diverse material types makes them highly versatile.
• Crane Mobility and Reach: When used with cranes, clamshell buckets benefit from the crane's inherent mobility and reach, allowing them to access and handle materials over a wide area or at significant heights and depths. Crane-mounted clamshell buckets offer extended reach and coverage. Yuantai's clamshell grab cranes have been sold to many countries and have been well received.
• Efficient in Confined Spaces: Clamshell buckets are often more maneuverable and efficient than larger excavation equipment in confined urban sites or areas with limited access. Their vertical digging capability is particularly advantageous in tight spaces.

Types of Clamshell Buckets

While we've discussed material-based classifications (mechanical, hydraulic, electro-hydraulic), clamshell buckets can also be categorized based on their overall design and operational characteristics:

Categorization Based on Operation:

• Cable Operated (Mechanical): As described earlier, these use cables and levers for jaw control. Cable operated clamshell buckets are known for their robustness and simplicity.
• Hydraulic: Utilize hydraulic cylinders for powered jaw operation, offering greater digging force and precise control. Hydraulic clamshell buckets are popular for demanding excavation and bulk handling tasks.
• Electro-Hydraulic: Combine electric power with hydraulic actuation, offering a balance of power and cleaner operation. Electro-hydraulic clamshell buckets are increasingly favored for indoor and environmentally sensitive applications.

Categorization Based on Design and Application:

• General Purpose Clamshell Buckets: Designed for a wide range of general material handling and excavation tasks, typically with robust construction and versatile jaw designs. General purpose clamshell buckets are all-rounders for common applications.
• Heavy-Duty Clamshell Buckets: Reinforced construction and heavier materials for handling very dense and abrasive materials like heavy aggregates, ores, and scrap metal. Heavy-duty clamshell buckets are built to withstand extreme conditions.
• Dredging Clamshell Buckets: Specifically designed for underwater dredging, often with heavier construction, sealed components, and specialized jaw designs for efficient sediment removal. Dredging clamshell buckets are engineered for underwater performance.
• Light-Duty Clamshell Buckets: Lighter construction for handling lighter materials like grains, fertilizers, or loose fill. Light-duty clamshell buckets are optimized for efficiency in handling less dense materials.
• Orange Peel Grapples (Multi-Tine Grapples): While technically grapples, these are sometimes considered a type of clamshell bucket variant, featuring multiple tines or jaws instead of two shells, used for handling bulky and irregular items like scrap metal, rocks, or waste. Orange peel grapples offer enhanced gripping for irregular loads.

• Bucket Capacity: The volume of material the bucket can hold when fully closed, typically measured in cubic yards or cubic meters. Clamshell bucket capacity should be matched to the crane's lifting capacity and the desired material handling rate.
• Jaw Design and Cutting Edges: The shape and design of the jaws, including the cutting edges, influence the bucket's digging and grabbing performance in different materials. Sharp, hardened cutting edges are essential for efficient excavation. Clamshell bucket jaw design is critical for digging efficiency.
• Closing Force and Digging Power: The closing force exerted by the bucket's mechanism (hydraulic cylinders or cables) determines its digging and grabbing power. Higher closing force is needed for denser and more compacted materials. Clamshell bucket closing force dictates digging performance.
• Bucket Weight and Material of Construction: The bucket's weight impacts the crane's net lifting capacity. Bucket material (steel type, thickness) determines its strength, durability, and wear resistance. Clamshell bucket weight must be considered in crane load calculations.
• Rotation and Positioning Options: Some clamshell buckets offer rotation capabilities, allowing the operator to rotate the bucket horizontally for precise material placement. Rotators can be hydraulic or mechanical. Rotating clamshell buckets enhance maneuverability.
• Durability and Wear Resistance Features: Look for buckets with hardened steel cutting edges, wear plates in high-wear areas, and robust construction to ensure long service life in demanding applications. Wear-resistant clamshell buckets minimize maintenance and downtime.
• Maintenance Access and Ease of Component Replacement: Design features that facilitate easy access to lubrication points, wear parts, and hydraulic components simplify maintenance and reduce downtime.

Safety and Maintenance

Like all crane attachments, clamshell buckets require regular inspection and maintenance to ensure safe and reliable operation. Neglecting maintenance can lead to performance issues and safety hazards.

Key Safety and Maintenance Practices:

• Regular Visual Inspection: Conduct routine visual inspections of the clamshell bucket before each use. Check for:
  • Jaw Condition: Inspect jaws for damage, cracks, wear, or deformation.
  • Cutting Edge Wear: Check cutting edges for wear and sharpness. Replace worn cutting edges as needed for optimal digging performance.
  • Hinge and Pivot Points: Inspect hinges, pivot points, and linkages for wear, looseness, or damage. Ensure smooth and free movement.
  • Hydraulic Cylinder Leaks (for hydraulic buckets): Check for hydraulic fluid leaks around cylinders, hoses, and fittings. Address leaks promptly.
  • Cable Wear (for mechanical buckets): Inspect cables for fraying, wear, or damage. Replace worn cables immediately.
  • Bolt and Fastener Tightness: Check that all bolts and fasteners are tight and secure.
• Lubrication: Regularly lubricate all pivot points, hinges, and moving parts according to the manufacturer's recommendations. Proper clamshell bucket lubrication minimizes wear and ensures smooth operation.
• Cutting Edge Replacement: Replace worn cutting edges periodically to maintain digging efficiency. Dull cutting edges reduce productivity and increase stress on the bucket and crane.
• Hydraulic System Maintenance (for hydraulic buckets): Maintain hydraulic systems according to manufacturer's guidelines, including fluid level checks, hose inspections, and filter replacements. Hydraulic clamshell bucket maintenance is crucial for reliable hydraulic operation.
• Cable Inspection and Replacement (for mechanical buckets): Implement a schedule for regular inspection and replacement of cables in mechanical clamshell buckets, based on usage and wear.

Conclusion

Clamshell buckets play an important role in many industries. Their ability to grab, lift, and move loose bulk materials, combined with their excavation and dredging capabilities, makes them indispensable tools for modern material handling and construction operations. Whether you're moving mountains of aggregates, excavating deep foundations, or dredging waterways, the crane clamshell bucket is often the ideal solution for getting the job done effectively and economically. Yuantai offers grab cranes with a wide range of grab types to choose from, and we can also customize them to meet your different needs for your application.