Clamshell Grabs

What are clamshell grabs?

Clamshell grabs use two opposing shells to scoop and retain loose bulk material. They are used with cranes, material handlers and excavators for sand, soil, grain, waste and other flowable materials.

This guide is intended as a practical starting point for comparing attachment types. Final compatibility always depends on the exact carrier, mounting interface, hydraulic setup, operating weight and the manufacturer limits for the complete configuration.

Common types and configurations

• Hydraulic clamshell grabs use cylinders or hydraulic drives for controlled opening and closing.
• Cable-operated grabs are common on cranes and bulk-handling equipment.
• Digging clamshells use stronger teeth and shells where the tool must penetrate compacted material.

Names vary between markets and manufacturers. Compare the working principle and rated limits rather than assuming two products with the same general name are interchangeable.

Selection criteria

Bulk density

The grab volume must be matched to material weight and carrier lifting capacity.

Shell profile

Closed shells retain fine material; open or perforated designs suit drainage or coarse bulk products.

Closing force

Free-flowing material needs less penetration force than compacted soil or waste.

Suspension

Check rotator, link, hook or crane connection and overall working height.

Cycle requirements

Opening speed, closing speed and swing control influence bulk-handling productivity.

Working setup

• Load symmetrically so both shells close around the material rather than one edge carrying the full load.
• Avoid dragging a suspended grab sideways through piles unless the design permits digging action.
• Keep personnel away from the drop zone and below suspended grabs.

Plan the work area, machine position and material movement before starting. Attachment productivity depends on a stable carrier, correct operator technique and a setup that keeps hoses, couplers and structures away from avoidable impact.

Carrier and hydraulic compatibility

Check the carrier operating weight, lifting chart or rated capacity, approved mounting interface, auxiliary hydraulic flow and pressure, return-line requirements and electrical controls where applicable. Include the attachment, coupler, rotator, adapter and carried material when assessing the complete working load.

A physical connection does not prove compatibility. Use the attachment and carrier documentation for the exact models and configuration.

Maintenance and wear checks

• Inspect cutting edges, shell alignment, hinge pins, cylinders and suspension components.
• Check that both shells close evenly and without excessive free play.
• Monitor cracks where shell plates join arms and high-load pivots.

Short daily inspections are particularly valuable on attachments because pins, wear edges, hoses and working tools are exposed directly to impact, contamination and abrasive material.

Questions before choosing

Clamshell or orange-peel grapple?

Clamshell grabs suit loose bulk materials; orange-peel grapples are better for irregular scrap and mixed waste.

How is capacity chosen?

Use bulk density and the complete lifting chart, not volume alone.

Do clamshell grabs rotate?

Many installations include a rotator, but it must be rated for the grab and load.

Before ordering

Ask for the dimensional drawing, attachment weight, rated capacities, hydraulic requirements, mounting information, wear-part list and service intervals. Confirm how the attachment changes the carrier working envelope and whether additional guarding, case drain, electrical control, pressure limitation or hose routing is required.

The related machine, application and category guides shown with this page can be used to compare alternative attachment families for the same job.