FIELD: mechanical engineering. SUBSTANCE: elongated member, for instance, gear to clean surfaces of walls is moved along specified meander figure of blasting. Member is installed in two cardan joints placed at distance one from another. First joint is fixed immobile and the other one is moved along first spindle which ends are capable of axial translation along two parallel spindles. Two contactless inductive limit switches connected to programmed control unit correspond to first and one of two other spindles. Some limit switches register reference point in vertical and horizontal directions and other limit switches register revolutions of spindles as measure of path covered by second cardan joint. Pulses of limit switches proportional to path are compared in control unit with specified figure of blasting and spindles are controlled depending on this figure. EFFECT: provision for control over elongated element with obtainment of specified figure of blasting. 1 cl, 3 dwg
