Mechanical Clamshell Grab Bucket

Product Overview

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 pontes rolantes, port cranes, guindastes de pórtico, 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?

Tipos

How Does It Work?

Especificações

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.

Two-Rope Mechanical Clamshell Grab

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.

Rope Configuration: 1 hoist rope + 1 closing rope
Grab Capacity: 0.5–30 m³, depending on the model
Shell Type: Two-shell clamshell
Typical Materials: Sand, gravel, coal, grain, and similar bulk materials
Application: General loading, unloading, and material transfer

Four-Rope Mechanical Clamshell Grab

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.

Rope Configuration: 2 hoist ropes + 2 closing ropes
Grab Capacity: Selected according to crane capacity and material density
Shell Type: Two-shell or multi-shell configuration
Typical Materials: Coal, ore, gravel, limestone, and other bulk materials
Application: Heavy-duty loading, unloading, and bulk material transfer

How Does It Work?

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.

1. Lower: The crane lowers the grab onto the bulk material with the shells open.
2. Close: The closing rope is pulled, bringing the two shells together and allowing them to penetrate the material pile.
3. Lift: The hoist rope raises the closed grab with the captured material.
4. Discharge: At the unloading position, the closing rope is released, and the shells open to discharge the material.

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.

Especificações

Parâmetro	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
Certificação	CE, ISO 9001

Capacity and Crane Matching: Grab capacity is selected according to material density, required load per cycle, and crane SWL. The grab’s dead weight is also included when checking the crane hook load.

Rope Configuration: Two-rope grabs use separate hoist and closing ropes for opening, closing, and lifting. Three-rope and four-rope designs provide additional control for larger grabs and demanding handling conditions.

Shell and Material Selection: Shell configuration depends on the material and working conditions. Q355B is used for the main structure, while NM400 or NM500 wear-resistant steel can be used on shells, teeth, adaptors, and cutting edges for abrasive materials.

Customized Design: Capacity, shell configuration, rope system, material, and crane connection can be specified according to the crane and operating conditions.

Vantagens

Simple Mechanical Structure — Rope-operated design with fewer power components and no separate hydraulic power unit.

Strong Material Penetration — Hinged shells close into loose material piles for effective loading and bulk material pickup.

Wide Material Compatibility — Suitable for coal, ore, sand, gravel, grain, fertilizer, and other loose bulk materials.

Multiple Capacity Options — Different grab volumes can be matched to material density, required payload, and crane capacity.

Easy Crane Integration — Designed for compatible overhead cranes, gantry cranes, port cranes, and other rope-operated lifting systems.

Low Maintenance Requirements — The mechanical rope system has a straightforward structure, making inspection, servicing, and replacement of wear parts easier.

Aplicações

Mechanical Clamshell Grab Buckets are used for loading, unloading, and transferring loose bulk materials in industrial and material handling operations.

Ports and Terminals

Loading and unloading coal, ore, grain, and other bulk cargo.

Mining

Handling ore, crushed rock, and other mined materials.

Steel Plants

Charging and transferring raw materials such as iron ore, coal, and limestone.

Usinas de energia

Handling coal, fly ash, and other bulk materials.

Sand and Gravel Plants

Loading sand, gravel, and crushed stone.

Fertilizer and Grain Handling

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 Clamshell Grab Bucket vs. Hydraulic Clamshell Grab Bucket

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.

Comparação	Mechanical Clamshell Grab Bucket	Hydraulic Clamshell Grab Bucket
Drive Method	Wire rope and mechanical linkage	Hydraulic cylinder
Fonte de alimentação	Crane lifting mechanism	Hydraulic power unit
Operation	Open and close through crane movement	Controlled directly by hydraulic system
Tipo de Grua	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
Manutenção	Simple mechanical structure	Requires hydraulic system maintenance
Aplicação	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?

How to Select a Mechanical Clamshell Grab Bucket

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?

Customization: Mechanical Clamshell Grab Bucket

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.

Bucket Capacity: Selected for the required load per cycle and material density
Grab Weight: Matched to the crane’s lifting capacity
Rope Configuration: Two-rope, three-rope, or four-rope
Jaw Opening: Sized for the material and loading conditions
Shell Structure: Configured for the type and condition of the material
Wear-Resistant Material: Options for abrasive bulk materials
Crane Connection: Matched to the crane hook and lifting system
Working Environment: Adapted to port, mining, steel, power, and other industrial sites

Provide the crane model or lifting capacity, material type, bulk density, and required grab capacity to start the design.

Customization Mechanical Clamshell Grab Bucket

Mechanical Clamshell Grab Bucket Manufacturer and Supplier

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.

Contacte-nos with your crane and material handling requirements for a mechanical clamshell grab bucket quotation.

FAQ

What is a Mechanical Clamshell Grab Bucket?

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.

How does a Mechanical Clamshell Grab Bucket work?

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.

What materials can a Mechanical Clamshell Grab Bucket handle?

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.

What is the capacity of a Mechanical Clamshell Grab Bucket?

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.

What is the difference between a two-rope and four-rope grab bucket?

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.

What crane can be used with a Mechanical Clamshell Grab Bucket?

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.

How do I choose the right clamshell grab bucket?

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.

Can WEIHUA customize a Mechanical Clamshell Grab Bucket?

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.

Serviço Pós-Venda

Fundada em 1988, a Weihua evoluiu para uma líder global no campo da manufatura inteligente na China. Somos especializados em I&D e produção de gruas inteligentes, ao mesmo tempo que oferecemos soluções AGV. As nossas equipas profissionais de engenharia, entrega e pós-venda fornecem suporte técnico multifacetado, soluções personalizadas, orientação de instalação no local e serviços globais de resposta rápida para garantir que cada projeto opere de forma segura e eficiente.

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