The Distinctive Characteristics of Three Types of Grab Attachments

The Distinctive Characteristics of Three Types of Grab Attachments

Hydraulic Grab

FOR EXCAVATORS OR CRANES WITH HYDRAULIC DRIVE

The hydraulic grab does not have its own drive. The excavator’s hydraulic drive provides the power. It is directly connected to the excavator’s suspension and hydraulic supply lines.

As with a motorized grab, the closing force is transmitted to the material through a convenient lever ratio combined with the appropriate dead weight. The only difference is that the grab does not include a hydraulic drive. A relatively rigid connection to the excavator provides an additional means of transmitting force.

Rope Grab 

FOR CRANES WITH SUSPENSION AND CLOSING ROPES 

A rope grab is used on a crane with two lifting drums. These are the drum with the closing rope and the drum with the suspension rope.The grab is suspended from the suspension rope. The grab body is opened and closed using the closing ropes and an integrated pulley block. (The closing ropes are repeatedly rerouted through the traction sheaves.)

Depending on the number of closing and suspension ropes, grabs are classified as single-rope,double-rope and four-rope.

The rope grab receives the force to close and collect the material due to its own weight, the ratio of the levers and the rearrangement of the pulley block.

Motorized Grab

FOR CRANES WITH SUSPENSION ROPES AND ELECTRIC WIRE

The motorized grab operates on a crane with one or two suspension rope drums. It has its own hydraulic drive, consisting of an electric motor, a hydraulic pump, and hydraulic components.

Electrical power is supplied from the crane via an electrical cable, which may also include control lines. The hydraulic drive provides the motorized gripper with closing force. This force is transmitted to the material through a convenient lever ratio combined with the appropriate dead weight.