Abstract: A threaded joint for coupling two drill rod elements includes a first drill rod element having at least one end thereof a male tapered helical threading with a cone opening angle greater than 1.degree. and less than 3.degree.. The threading has a constant pitch determining an angle of inclination of the decreasing helix as greater than 1.degree. and less than 3.degree. at the beginning of the helical threading. A second drill rod element has corresponding female tapered helical threading. Each tapered helical threading has primary and secondary shoulders on opposite ends thereof and a stand-off between the primary shoulders when the male and female tapered helical threading are manually fitted together. The male tapered helical threading has discharge grooves in an unthreaded zone for deflection of lines of force.

Abstract: A vertical gang saw produces an ovoidal sawing curve when the frame has at each corner attached feet that are engaged in slide bars which themselves are attached by an extremity to the body of the machine. The lower and upper slide bars undergo a synchronized swing movement that is transmitted by small drive rods. The lower drive rods are driven by an eccentric gear moved vertically. The upper drive rods are driven by an oscillating pinion with a double cam.

Abstract: The invention relates to a device for closing, without a surge, one end of a core barrel installed in a mining or oil drilling rig, optionally equipped with a turbine.This device comprises a tubular element in whose bore there is guided a sliding member which provides a passage for the drilling liquid under pressure, this sliding member being movable in the above-mentioned bore under the influence of a variation in the flow of drilling liquid between a first position in which it keeps a closing member such as a ball remote from a seat provided at the above-mentioned end of the core barrel and, when it has engaged in the second section of the bore allows the closing element to be held in the first section of the bore, and a second position in which it allows the closing element to pass from the first section of the bore into the second section thereof and to place itself on the seat of the core barrel when the sliding member returns to its starting position.

Abstract: In accordance with the invention, on the periphery of the motor wheel (8) and the return wheel (9) of a cutting arm, grooves (18) are provided which are separated from one another by ridges (19). This arrangement enables the traction couple to be transmitted to the endless component (10), which is provided on the exterior with cutting tools (11) and on the interior with guide plates (12), by the assembly of fibers adjacent to the principal fibers of the endless component (10) and not by the guide plates (12).

Abstract: There is provided a surface-dressing tool for petrous materials exhibiting a better bite for a lower sound level and a lower energy consumption in that it comprises a pair of cylindrical surface-dressing rollers mounted rigidly on the ends of axles extending parallel between them. The driving force on a pair of rollers on one and the same axle is the resultant of the friction components of opposite sign of each roller in relation to the working surface.

Abstract: A higher performance, lighter and thinner composite sawing disc for stony materials is made by assembling, preferably by bonding, a peripheral rim (2) provided with diamond segments (6) on a self-supporting, metallic honeycomb structure (3) strengthened at its center by a central ring (4). Excellent strength of the assembly is obtained by bonding annular discs (5) of thin plate to the lateral faces.