Support-arm assembly for a drill or borer, particularly for subterranean applications

A drilling maching comprising:

• a column mounted for rotation about a substantially upright first axis;
• first motor means connected to said column for angularly displacing same about said first axis with an angular displacement represented by the parameter .alpha.1;
• an arm pivotally connected to said column at a second axis substantially perpendicular to said first axis;
• second motor means connected between said column and said arm for angularly displacing said arm about said second axis, the angular displacement of said arm about said second axis being represented as a parameter .alpha.2;
• an intermediate support body carried by said arm;
• third motor means connected between said support body and said arm for rotating said support body about a third axis generally perpendicular to said second axis with the angular displacement of said support body being represented by a parameter .alpha.3;
• a rail support pivotally mounted on said support body and carrying a rail for a drilling head;
• fourth motor means connected between said support body and said rail support for pivotally displacing said rail support relative to said support body through an angle represented by the parameter .alpha.4;
• control means for said motor means including
• at least one manual control element operatively connected to said first and second motor means for actuating same,
• respective displacement detectors responsive to displacements produced by said first and second motor means for generating signals representing the parameters .alpha.1 and .alpha.2, and
• follower means connected to said displacement detectors and responsive to the parameters .alpha.1 and .alpha.2 for establishing continuously the values of the parameters .alpha.3 and .alpha.4 defining the orientation of said rail to maintain the same parallel to itself, and automatically controlling said third and fourth motor means in response to the parameters .alpha.3 and .alpha.4 calculated in the follower means;
• telescoping means on said first arm for selectively displacing said fourth axis toward and away from said first axis without modifying the orientation of said rail, said first and second motor means each being a respective hydraulic cylinder, said third and fourth motor means being a rotary hydraulic motor and a hydraulic cylinder, respectively;
• means for disconnecting said follower means and independently controlling said third and fourth motor means;
• and
• a ball-and-socket joint disposed between the bottom of said column and a pedestal, and a pair of hydraulic cylinders having mutually orthogonal axes connected to said column for displacing same about a pivot point defined by said ball-and-socket joint.