This invention relates to drilling apparatus and more particularly to such apparatus which embodies an elongated frame which supports a transmission unit for longitudinal movement therein with the transmission unit connecting a polygonal drive shaft to a driven head which is threadedly connected to a drill rod section for drilling a hole into the earth.
Heretofore in the art to which my invention relates, power is imparted to one end only of the polygonal drive shaft whereby rotary motion is then transmitted through the transmission unit to a driven head operatively connected to a drill rod section. In view of the fact that the elongated frame and the polygonal drive shaft are both relatively long and a considerable amount of torque is applied to the driven end of the shaft, fatigue often occurs in the polygonal shaft and in the elongated supporting frame.
Difficulties have also been encountered in conventional type drilling apparatus having an elongated supporting frame with means for transmitting rotary motion from a polygonal drive shaft through a transmission to the drill rod sections due to the fact that all operating parts, including the polygonal shaft and transmission are exposed whereby the apparatus is not only hazardous to the operators of the drill but the various components of the drive mechanism are unprotected whereby they may be easily damaged.
Furthermore, difficulties have been encountered with conventional type drilling apparatus due to the fact that it has been the usual practice to erect the drilling apparatus at a location to drill a single hole downwardly into the earth whereupon the entire apparatus is then moved to the next location where the next hole is drilled. This operation consumes a considerable amount of time and effort due to the fact that the translatable frame which supports the drilling apparatus must be moved to each separate location whereupon its supporting jacks are then extended to support the apparatus in a level position for drilling. Also, the distance between each drilling site must be accurately measured prior to moving the drilling apparatus from one drilling site to the next.