Drive Method and Operating Principle
Electric-hydraulic grab:
An internal motor drives a hydraulic pump, using hydraulic oil pressure to control the opening and closing of the grab. Its power source is independent of the crane and requires a separate power supply and drum power supply. The hydraulic system utilizes valves, seals, and other components for precise control. The grab's closing force is determined by the hydraulic cylinder pressure, making it suitable for high-load applications.
Mechanical grab:
It relies on external force and is typically connected to the crane via a dual-rope or single-rope system. A dual-rope grab uses two steel cables to control both lifting and opening, while a single-rope grab uses an internal mechanical mechanism to open and close. It is powered entirely by the crane and does not have an independent power source.
Control Precision and Operational Flexibility
Electro-hydraulic Grabs:
The hydraulic system offers high control precision, allowing for adjustable opening and closing speed, force, and closing position. This type of grab is suitable for applications where gripping accuracy is less critical, such as grasping fragile or irregular materials. Some models are equipped with a remote control for automated operation.
Mechanical Grabs:
Control precision is lower, and opening and closing speed and force are affected by wire rope tension and crane operation, making precise adjustment difficult. This type of grab is suitable for applications where gripping accuracy is less critical, such as bulk handling.
