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A mechanical clamshell grab bucket is a two-shell attachment used for handling loose bulk materials such as coal, sand, grain, scrap, and ore. It is commonly installed on cranes, including overhead cranes, port cranes, gantry cranes, and ship unloaders. The grab opens and closes through the crane lifting mechanism to scoop, hold, and discharge materials. Also known as a mechanical grab or rope-operated grab bucket, simple structure, reliable operation, and easy maintenance without a separate hydraulic power unit.
The grab hangs from the crane hook. Hoist and closing ropes run through the upper and lower sheaves. The jaws close under their own weight and the pull of the closing rope, cutting into the material pile. Releasing the closing rope opens the jaws for discharge. Motor-driven models use an onboard motor for jaw movement instead of a closing rope. The operator handles the material from the crane without direct contact.
The shells are welded from Q345B or NM400 wear-resistant steel. The head, sheaves, ropes, and hinge pins are sized according to the rated load. Capacities range from 0.5 to 30 m³ and are selected according to crane capacity and material density. Materials include coal, ore, sand, gravel, cement clinker, fertilizer, and grain. Common applications include ports, mines, steel plants, power stations, and waste-to-energy facilities.
For more information, read the article: What Is a Crane Grab Bucket?
Mechanical clamshell grab buckets are mainly available in two-rope and four-rope configurations. The rope arrangement affects how the grab is operated and must match the crane’s rope system. Selection also depends on grab capacity, material, and working conditions.
A two-rope mechanical clamshell grab uses one hoist rope and one closing rope. The hoist rope raises and lowers the grab, while the closing rope operates the shells. It has a straightforward rope arrangement and is suitable for general handling of sand, gravel, coal, grain, and other loose bulk materials.
A four-rope mechanical clamshell grab uses separate hoist and closing ropes for the grab mechanism. The arrangement gives better control of shell movement and is suited to larger grabs and heavier handling work. It is commonly used for bulk material handling in ports, mines, steel plants, and other industrial facilities.
A mechanical clamshell grab bucket operates through the crane hoist rope and closing rope. The hoist rope lifts and lowers the grab, while the closing rope controls two hinged shells. The head and sheave assembly transfers rope force to the shells, with hinge pins allowing them to open and close. The grab connects to the crane through a suspension link or similar connector.
The mechanical clamshell grab uses the crane’s rope system rather than a separate hydraulic power unit. This configuration is suitable for repetitive handling of loose bulk materials such as coal, ore, sand, and gravel.
| Parameter | Value / Options |
|---|---|
| SWL (Lifting Capacity) | 5.0–25.0 t; 30 t or higher on request |
| Grab Capacity | 1.4–8.0 m³ standard; 0.5–30 m³ customized |
| Dead Weight | 2,640–12,200 kg |
| Shell Configuration | 2-shell; multi-jaw; 6-peel available |
| Rope Configuration | Two-rope, three-rope, four-rope |
| Pulley Diameter | 315–630 mm |
| Main Material | Q355B, Q460, NM400, NM500 |
| Certification | CE, ISO 9001 |
Mechanical Clamshell Grab Buckets are used for loading, unloading, and transferring loose bulk materials in industrial and material handling operations.
Loading and unloading coal, ore, grain, and other bulk cargo.
Charging and transferring raw materials such as iron ore, coal, and limestone.
Handling coal, fly ash, and other bulk materials.
Loading sand, gravel, and crushed stone.
Moving free-flowing agricultural and processed bulk materials.
The grab capacity, shell configuration, and rope system are selected according to the material density, required load per cycle, and crane capacity.
To learn more about the specific applications of crane grab buckets in heavy-duty industries, read the article: “Crane Grab Bucket Applications in Ports, Steel Mills, Mining, and Bulk Material Handling”
Mechanical and hydraulic clamshell grab buckets both handle loose bulk materials with two shells. The main difference is the shell opening and closing mechanism. Mechanical grabs use the crane’s rope system, while hydraulic grabs use hydraulic cylinders and a hydraulic power system.
| Comparison | Mechanical Clamshell Grab Bucket | Hydraulic Clamshell Grab Bucket |
|---|---|---|
| Drive Method | Wire rope and mechanical linkage | Hydraulic cylinder |
| Power Source | Crane lifting mechanism | Hydraulic power unit |
| Operation | Open and close through crane movement | Controlled directly by hydraulic system |
| Crane Type | Overhead crane, gantry crane, port crane | Overhead crane, gantry crane, port crane |
| Control | Mechanical operation | Hydraulic control |
| Typical Materials | Coal, sand, grain, ore, scrap | Scrap steel, ore, bulk materials, irregular cargo |
| Maintenance | Simple mechanical structure | Requires hydraulic system maintenance |
| Application | General bulk material handling | Heavy-duty and controlled grabbing operations |
Mechanical clamshell grabs are suited to standard bulk material handling where a simple rope-operated structure is preferred. Hydraulic clamshell grabs are used when independent shell control, stronger gripping force, or more precise grabbing is required.
For details on the different applications of grab buckets and how to choose the right one, see: Different Types of Crane Grab Buckets and How to Choose the Right One
Mechanical and hydraulic grab buckets differ significantly in their applications and configurations. For more details, see the article: Mechanical Clamshell Grab Bucket vs. Hydraulic Grab Bucket: What Is the Difference?
The right mechanical clamshell grab bucket depends on the material being handled, required capacity, and the crane’s lifting system. The grab weight must also be included when checking the crane’s rated load.
1. Material Type and Density: Identify the material and its bulk density before selecting the grab. Coal, ore, sand, gravel, and grain require different shell designs and capacities.
2. Required Grab Capacity: Select the bucket volume according to the required load per cycle and material density. A larger volume is not always suitable if the crane cannot handle the loaded grab weight.
3. Crane Capacity and Hook Height: Check the crane’s SWL, hook height, and rope arrangement. The crane must handle the combined weight of the grab and material.
4. Rope Configuration: Match the grab with the crane’s rope system. Two-rope and four-rope configurations have different operating arrangements and should not be selected independently of the crane.
5. Working Conditions: Consider handling frequency, material abrasiveness, pile depth, and operating environment. Wear-resistant shells and reinforced components may be required for heavy or abrasive materials.
Select the grab based on the material, bulk density, required capacity, and crane specifications. The grab weight, rope configuration, and working conditions should also match the crane.
If you are considering using an overhead crane or gantry crane and are unsure how to select the appropriate grab bucket, see the article: How to Choose a Grab Bucket for Overhead Cranes and Gantry Cranes?
Mechanical clamshell grab buckets can be designed for different crane systems, bulk materials, and working conditions. The grab size and structure are selected according to the required load, material density, lifting capacity, and operating cycle.
Provide the crane model or lifting capacity, material type, bulk density, and required grab capacity to start the design.
Get Custom Quotation Now
WEIHUA manufactures and supplies mechanical clamshell grab buckets for overhead cranes, gantry cranes, port cranes, and other lifting systems. Custom designs cover grab capacity, dead weight, rope configuration, jaw opening, shell structure, wear-resistant materials, and crane connection. The equipment is used for coal, ore, sand, gravel, grain, and other bulk materials.
WEIHUA has experience supplying lifting equipment to overseas markets and holds relevant quality certifications. Technical support covers grab selection, design, production, delivery, and installation guidance. Spare parts and after-sales service are also available.
Contact us with your crane and material handling requirements for a mechanical clamshell grab bucket quotation.
A mechanical clamshell grab bucket is a rope-operated crane attachment with two hinged shells. It is used to scoop, lift, and discharge loose bulk materials such as coal, ore, sand, gravel, and grain.
The crane lowers the open grab onto the material. The closing rope pulls the shells together to capture the load. The crane lifts the closed grab, then releases the closing rope to open the shells and discharge the material.
It can handle coal, ore, sand, gravel, cement clinker, fertilizer, grain, and other loose bulk materials. Shell design and wear-resistant materials can be selected according to material density and abrasiveness.
Grab capacity can range from 0.5 to 30 m³, depending on the model and configuration. The required capacity is selected according to material density, crane lifting capacity, and the required load per cycle.
A two-rope grab uses one hoist rope and one closing rope. A four-rope grab uses separate hoist and closing ropes on both sides. The rope configuration must match the crane and grab design.
Mechanical clamshell grabs can be used with compatible overhead cranes, gantry cranes, port cranes, and other rope-operated lifting systems. Crane SWL, hook height, and rope configuration should be checked before selection.
Check the material type, bulk density, required capacity, crane SWL, rope configuration, and working conditions. These factors determine the suitable grab size, shell design, and operating arrangement.
Yes. Custom options include bucket capacity, grab weight, rope configuration, jaw opening, shell structure, wear-resistant materials, and crane connection. The design can be specified according to the material and working conditions.
Weihua, founded in 1988, has evolved into a global leader in China's intelligent manufacturing field. We specialize in smart crane R&D and production while offering AGV solutions. Our professional engineering, delivery, and after-sales teams provide one-stop technical support, customized solutions, on-site installation guidance, and rapid-response global services to ensure every project operates safely and efficiently.
Contact us now via email: [email protected], or fill in the form below.
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