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Operation cycle of a dipper shovel, for example, consists 1 the following elements (as shown in Fig.1): digging, raising the bucket up from the face base(B); bringing the stick 2 (C) ; pulling the bucket 3 from the face (D) ; swinging the boom to the dumping place (E); 4 the bucket for dumping (F); dumping the bucket by opening its door and turning it round 5 to the face and setting is at the same time in its 6 position (A). Fig.1: Operating cycles of revolving shovels The power unit of a shovel may be a 7 , an electric powered from an external supply, or a diesel-electric drive. The running gear of the revolving shovels 8 into crawler-mounted shovels to operate on ordinary soil, shovels with 9 caterpillars to dig soft, very moist and boggy soil, and air-tired shovels ,which are essentially four- or six- wheel 10 designed expressly to carry the shovels or an automobile-mounted shovel on a normal or reinforced chassis.