Well drilling apparatus

A drill rig for drilling wells having a derrick adapted to hold and lower a conductor string and drill pipe string. A support frame is fixed to the derrick to extend over the well to be drilled, and a rotary table, for holding and rotating drill pipe strings, is movably mounted thereon. The table is displaceable between an active position in alignment with the axis of the well and an inactive position laterally spaced therefrom. A drill pipe holder is movably mounted on the frame below the rotary table for displacement between a first position laterally of the axis of the well and a second position in alignment with the axis of the well. The rotary table and said drill pipe holder are displaced in opposition to each other, so that the rotary table may be removed from alignment with the axis of the well and said drill pipe string simultaneously held without removal from said well.