Hdd machine with lowered driveline

Abstract

A horizontal directional drilling machine including a drilling frame defining a longitudinal axis. A rack gear is mounted on the drilling frame and has a pitch plane parallel to the longitudinal axis. A carriage assembly includes a carriage frame extending over the rack gear while being mounted with a linear bearing assembly. A thrust drive motor is mounted on the carriage frame with no portion thereof extending outboard of the carriage assembly. The thrust drive motor has an output shaft with a pinion gear meshed with the rack gear to define a carriage positioning axis. A rotary drive assembly is mounted on the carriage frame, including a drive spindle engaging a drill string. The central rotation axis of the drive spindle is offset from the carriage positioning axis by a distance equal to or less than 1.5 times an outer diameter of the drive spindle.

What is claimed is: 
     
         1 . A horizontal directional drilling machine comprising:
 a drilling frame defining a drilling frame longitudinal axis;   a rack gear mounted on the drilling frame, the rack gear having a pitch plane parallel to the longitudinal axis;   a carriage assembly including a carriage frame extending over the rack gear while being mounted with a linear bearing assembly for longitudinal movement along carriage guide surfaces of the drilling frame;   a thrust drive motor mounted on the carriage frame with no portion of the thrust drive motor extending laterally outboard of the carriage assembly, the thrust drive motor having an output shaft with a pinion gear meshed with the rack gear to define a carriage positioning axis as a longitudinal array of points of contact between the pinion gear and the rack gear that are nearest the thrust drive motor;   a rotary drive assembly mounted on the carriage frame, the rotary drive assembly having a drive spindle configured to engage a drill string for rotation about a longitudinal central rotation axis of the drive spindle, the drive spindle having an outer diameter,   wherein the central rotation axis of the drive spindle is offset from the carriage positioning axis by an offset distance equal to or less than 1.5 times the outer diameter of the drive spindle.   
     
     
         2 . The horizontal directional drilling machine of  claim 1 , further comprising:
 a rod box configured to hold a plurality of inactive drill rods connectable with the drive spindle;   a rod loader positioned underneath the rod box and provided with a rod transfer arm movable transverse to the longitudinal axis; and   a rod lifter assembly positioned underneath the rod box and operable to vertically lift a drill rod into the rod box,   wherein the rod transfer arm of the rod loader is positioned longitudinally nearer a downhole end of the drilling frame than the rod lifter assembly.   
     
     
         3 . The horizontal directional drilling machine of  claim 2 , further comprising:
 a second rod loader positioned underneath the rod box and provided with a second rod transfer arm movable transverse to the longitudinal axis; and   a second rod lifter assembly positioned underneath the rod box and operable to vertically lift a drill rod into the rod box,   wherein the second rod transfer arm is positioned longitudinally nearer the downhole end of the drilling frame than the second rod lifter assembly.   
     
     
         4 . The horizontal directional drilling machine of  claim 1 , wherein the carriage frame includes a pair of sliding supports supporting the rotary drive assembly by engagement with a rotary drive housing thereof at positions that laterally flank the drive spindle. 
     
     
         5 . The horizontal directional drilling machine of  claim 4 , wherein the central rotation axis of the drive spindle is positioned no higher than a reference line connecting respective centers of the pair of sliding supports. 
     
     
         6 . The horizontal directional drilling machine of  claim 1 , wherein a motor of the rotary drive assembly drives the drive spindle through an idler gear that rotates about an axis spaced from an output axis of the motor and spaced from the central rotation axis of the drive spindle. 
     
     
         7 . The horizontal directional drilling machine of  claim 6 , wherein the drive spindle is driven through a gearbox including a plurality of vertically-stacked gears including a rotary drive pinon gear, the idler gear, and a rotary drive final gear. 
     
     
         8 . The horizontal directional drilling machine of  claim 1 , wherein the linear bearing assembly between the carriage frame and the drilling frame is formed by the carriage guide surfaces along both of a pair of laterally outer ends of a plate of the drilling frame, each of the laterally outer ends of the plate being sandwiched between an upper carriage support and a lower carriage support. 
     
     
         9 . The horizontal directional drilling machine of  claim 8 , wherein the upper and lower carriage supports are supported on vertical side plates of the carriage frame adjacent each of the laterally outer ends of the plate of the drilling frame. 
     
     
         10 . The horizontal directional drilling machine of  claim 8 , wherein the rack gear is mounted to a planar top surface of the plate of the drilling frame. 
     
     
         11 . The horizontal directional drilling machine of  claim 1 , wherein the central rotation axis of the drive spindle is offset from the carriage positioning axis by an offset distance equal to or less than 1.35 times the outer diameter of the drive spindle. 
     
     
         12 . A horizontal directional drilling machine comprising:
 a drilling frame defining a drilling frame longitudinal axis;   a carriage assembly including a carriage frame extending over the drilling frame while being mounted with a linear bearing assembly for longitudinal movement along the drilling frame, the carriage frame having a thrust drive support portion and a rotary drive support portion;   a rotary drive assembly mounted on the carriage frame, the rotary drive assembly having a drive spindle configured to engage a drill string for rotation about a longitudinal central rotation axis of the drive spindle; and   a longitudinal positioning system including a thrust drive motor mounted on the carriage frame and operable to move the carriage assembly along the longitudinal axis via a mechanical drive mechanism spaced below the central rotation axis of the drive spindle,   wherein the carriage frame includes a pair of sliding supports supporting the rotary drive assembly by engagement with a rotary drive housing thereof at positions that laterally flank the drive spindle, and   wherein the central rotation axis of the drive spindle is positioned no higher than a reference line connecting respective centers of the pair of sliding supports.   
     
     
         13 . The horizontal directional drilling machine of  claim 12 , further comprising:
 a rod box configured to hold a plurality of inactive drill rods connectable with the drive spindle;   a rod loader positioned underneath the rod box and provided with a rod transfer arm movable transverse to the longitudinal axis; and   a rod lifter assembly positioned underneath the rod box and operable to vertically lift a drill rod into the rod box,   wherein the rod transfer arm of the rod loader is positioned longitudinally nearer a downhole end of the drilling frame than the rod lifter assembly.   
     
     
         14 . The horizontal directional drilling machine of  claim 13 , further comprising:
 a second rod loader positioned underneath the rod box and provided with a second rod transfer arm movable transverse to the longitudinal axis; and   a second rod lifter assembly positioned underneath the rod box and operable to vertically lift a drill rod into the rod box,   
       wherein the second rod transfer arm is positioned longitudinally nearer the downhole end of the drilling frame than the second rod lifter assembly. 
     
     
         15 . The horizontal directional drilling machine of  claim 12 , wherein the carriage frame includes a pair of sliding supports supporting the rotary drive assembly by engagement with a rotary drive housing thereof at positions that laterally flank the drive spindle. 
     
     
         16 . The horizontal directional drilling machine of  claim 15 , wherein the central rotation axis of the drive spindle is positioned no higher than a reference line connecting respective centers of the pair of sliding supports. 
     
     
         17 . The horizontal directional drilling machine of  claim 12 , wherein a motor of the rotary drive assembly drives the drive spindle through an idler gear that rotates about an axis spaced from an output axis of the motor and spaced from the central rotation axis of the drive spindle. 
     
     
         18 . The horizontal directional drilling machine of  claim 17 , wherein the drive spindle is driven through a gearbox including a plurality of vertically-stacked gears including a rotary drive pinon gear, the idler gear, and a rotary drive final gear. 
     
     
         19 . The horizontal directional drilling machine of  claim 12 , wherein the linear bearing assembly between the carriage frame and the drilling frame is formed by carriage guide surfaces along both of a pair of laterally outer ends of a plate of the drilling frame, each of the laterally outer ends of the plate being sandwiched between an upper carriage support and a lower carriage support. 
     
     
         20 . The horizontal directional drilling machine of  claim 19 , wherein the upper and lower carriage supports are supported on vertical side plates of the carriage frame adjacent each of the laterally outer ends of the plate of the drilling frame. 
     
     
         21 . The horizontal directional drilling machine of  claim 19 , wherein the mechanical drive mechanism includes a rack gear on a planar top surface of the plate of the drilling frame, the rack gear engaged by a pinion gear on an output shaft of the thrust drive motor.