For the production of all goods and energy, raw materials are the basic ingredient. Therefore, raw materials are shipped in large quantities worldwide. All materials have their own properties and for fast and efficient handling, specific grab solutions are required. The most efficient and reliable grabs for handling large amounts of bulk material are rope-operated mechanical grabs. These grabs have a beneficial ratio between dead weight and grabbing capacity. Bulk materials have properties from extremely light to very heavy; and from fine and free flowing to coarse and abrasive. There is a wide range of bulk handling grabs, optimised for specific materials. Clamshell grabs can be used for most bulk materials. For certain materials or specific operations other grabs are a better solution. Hereafter the scope of application and working of the different grab models is described.
WORKING OF A CLAMSHELL GRAB
In order to get a good filling a clamshell grab must be able to penetrate the bulk material. This is the case for all fine and free flowing materials like coal, agribulk and fertiliser. A standard clamshell grab with normal digging force is suitable for this operation. See opposite the infographic of the working of this kind of grab: For more difficult to penetrate materials, like iron ore, a heavy duty grab with more closing force is required. The higher closing force is generated by applying more ropes heaves in the grab. These grabs have more dead weight by which the digging force will increase as well. See below the infographic of this heavy duty grab for ores. Besides the higher weight and closing force this open model…
