Abstract: The invention relates to valves for wells.The overflow valve of a drill string comprises a hollow body (1) with side ports (2), a seat (4) which is part of the inner surface of the body (1), a shut-off element which is in fact an elastic sleeve (3) fitted with its one end in the body (1) and positioned therein with a gap (6). An effuser (7) is provided at the other end of the sleeve (3). Elimination of movable parts and units, increasing tightness of closing the passage for fluid to flow, decreasing hydraulic resistance of the overflow valve to the flow minimize wear and failure of the components and enhances operating reliability and durability of the valve.

Abstract: A working member of a helical downhole motor can have the form of either a rotor with outer helical teeth or a stator with inner helical teeth. The working member includes separate sections having helical teeth arranged in succession, one after another, and interconnected by rings. Each ring has helical teeth coinciding in pitch and direction with the helical teeth of the sections, and equidistant in profile. This allows automatic orientation of the helical teeth of the sections of the working member.

Abstract: A rotor (1) of a screw hydraulic downhole motor, made as a hollow multiple-start screw featuring a substantially constant wall thickness. The ratio of the length of the rotor (1) cross-sectional outside contour to the length of the circumscribed circle of the contour is substantially within 0.9 and 1.05. When making the rotor (1) a forming element is inserted into a tubular blank, and a fluid pressure is applied to the outside blank surface. A device for making the rotor comprises a hollow housing accommodating a forming element installed on centering bushings. The bushings have fitting areas adapted for the ends of the tubular blank to fit thereon.

Abstract: A casing having a gear ring formed on its inner wall and closed at each end with a cover is provided with two half-couplings arranged coaxially and having outer gear rings engaging the gear ring of the casing. A ball is disposed between the two half-couplings and the interior is filled with a lubricant. A seal is placed in the casing between each cover and the respective end face of the gear ring. Each seal is made out of an elastic material in the form of a sleeve embracing the half-coupling, and has one end abutting upon the end face of the gear ring and its other end secured to the half-coupling.

Abstract: An articulated coupling has two cylindrical half-couplings facing each other at their end faces. Recesses are formed in the end faces which recesses in which a cage is installed in the recesses with a clearance. Radial coaxial openings are formed in the cage and the half-couplings and rollers are installed in the coaxial openings with clearances. The half-couplings are provided with a device for holding the rollers in the openings.