2014 GH · WASTE TREATMENT CRANES (WTC) 07 DIFFERENT TYPES OF ELECTRICAL INSTALLATIONS TWO DIFFERENT CONFIGURATIONS ELECTRO HYDRAULICALLY DRIVEN GRABS ELECTROHYDRAULIC DRIVE MAIN CHARACTERISTICS MECHANICAL GRAB MAIN CHARACTERISTICS The orange peel grab or the clamshell grab are driven by an electrohydraulic unit, consisting of an electrical motor, a pump and hydraulic valves, which supply oil under pressure through duly protected hoses, to the cylinders operating teeth or shells. All these units are integrated in the orange peel grab or the clamshell grab body. The orange peel grab or the clamshell grab’s electrical supply is carried out through a spring reel or motorized cable reel, depending on the hoisting height and speed. Nowadays, most of the waste treatment cranes (WTC) are equipped with this type of grabs. MECHANICALLY DRIVEN GRABS The mechanically driven orange peel grab or the clamshell grab are generally equipped with four ropes. They are based on two closing ropes and two suspension ropes. This is why it is necessary to have a special lifting system with two drums. Both drums must make movements, sometimes in the same direction and sometimes in the opposite direction. ŸAs a general rule, higher opening and closing speed. ŸShorter maintenance time. ŸFrequent replacement of closing ropes required. ŸSince the grab seldom works horizontally, it can affect the rope systems. ŸHigher control of the working process. ŸLighter trolley and thus lighter crane for the same capacity. ŸSimpler electrical solutions. ŸBetter side approaches. ŸBetter filling rate, due to a better nailing into the waste mass. ŸShorter grabs replacement times. ŸSmaller height needed for grabs installation.
Waste Treatment Cranes (WTC)
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