Abstract: A waste comminuting device includes a comminuting housing (1), a rotor (2) provided with a plurality of protruding peripheral knives, stationary counterblades supported by the comminuting housing, the minimal distance separating each knife from each associated counterblade, during the passage of the knife opposite the counterblade, being equal to an operating clearance, called the cutting size. For each knife (3, 4, 5, 6) and for at least one direction of rotation of the rotor, at least two non-aligned counterblades (7 and 11, 8 and 12, 9 and 13, 10 and 14) associated with the knife are adapted so that the distance separating the leading edge (45) of the knife and the leading edge (48, 56) of a counterblade at the moment when the leading edge of the knife opposes the leading edge of the counterblade, is different from one counterblade (7-10) to another (11-14).

Abstract: The invention relates to the determination of the position of a self-contained operating apparatus movable along any line of displacement over any immersed structure.A follower apparatus is associated with the operating apparatus, and the position of this follower apparatus, along a line of displacement chosen as the reference line, is determined at any instant. The follower apparatus is displaced by the operating apparatus by servo-control means, and at any instant the transverse distance between the operating apparatus and the follower apparatus is monitored.