Abstract: A pipe string in an oil well has a cable 2 slidingly attached along it. It may be necessary to break the pipe string. Apparatus is provided for controlling the position of a fracture in the cable, as it is desirable to break the cable at about the same point. The apparatus comprises a pocket 1 attached to the cable and having a passage through which the cable passes, and upper and lower nipples 5 and 6 attached to the cable in the pocket. The lower face 5′ of the nipple 5 is skewed relative to the lower internal face 3′ of the pocket and the facing faces (5″, 6′) of the two nipples are skewed relative to each other, so bending and kinking the cable when tension is applied. The cable therefore breaks at the bend or kink. The pipe string includes a plurality of such apparatuses located at spaced points along its length.

Abstract: A drill bit including a body, a drill bit fixed onto the body, a thrust transmitting member arranged on the body and having a contact portion, and an undercut cutting member housed in a guide groove provided in the side face of the drill bit. The undercut cutting member is freely movable and provided with an undercut edge at the lower end thereof. A pull-up spring is installed to operably move the undercut cutting member, and a working force transmitting mechanism is installed on the body coupled with the thrust transmitting member and with the undercut cutting member, to press down the undercut cutting member against the resistance of the pull-up spring by the approaching movement of the body and the thrust transmitting member thereby to cause the undercut cutting edge to protrude outwardly of the drill bit body surface.

Abstract: A work stand for power operated tools such as, for example, an electrically powered hand drill, with the work stand including a supporting bracket adjustable along a guide column, a guide plate pivotable about a horizontal axis at the supporting bracket, a slide displaceable in a prismatic guide of the guideway, and a machine support carried by the slide. The machine support is adapted to be pivoted around the horizontal axis and is steplessly adjustable around both axes up to a full rotational angle so as to accommodate large rotational moments in a fixed condition. The guide plate and the machine support are each provided with a truncated conically-shaped axle journal accommodated in an associated conical pivot bearing respectively provided at the supporting bracket and the slide.

Abstract: A boring unit comprises a rotary spindle and a tool support mounted therein. The tool supports includes a rearwardly extending headbolt and a rearwardly extending supporting arm. The supporting arm engages an inclined wedge surface, the latter being movable by a connecting rod so that the wedge surface imparts rotary movement to the supporting arm and to the tool support about an axis of adjustment which is oriented perpendicular to the axis of rotation of the spindle, thereby moving the tool in a radial direction. The headbolt of the tool support is retained within a chucking cage. The chucking cage is movable to a position for releasing the headbolt by means of the movable connecting rod.