Abstract: A drilling rig carried by a vehicle includes a mast having upper and lower sections. The lower section is mounted on a support surface of the vehicle which is maintained parallel to the ground surface during drilling. The upper section is secured to the lower section so that the longitudinal axes of the upper and lower sections are offset at a predetermined acute angle and the top of the upper section is beyond an edge of the surface. A rotary power drill head is translatable along the length of the lower section. A cable pulled by a draw works on the vehicle extends over a pulley at the top of the upper section and thence downwardly. The angle of the surface is controlled so that during vertical hole drilling the surface is horizontal and the power drill head is directly above the hole. During pipe hoisting, the pulley is directly above the hole so the cable extends downwardly in line with the hole, while it is attached to the pipe.