A
transmitter in the drill head provides depth, position and pitch information to
an above-ground receiver (locator). The locating device displays this information
to the user, allowing the user to determine if any changes need to be made in
the direction of the drill path.
Specialized drilling fluids are pumped
through the drill rod and head to lubricate and seal the drill path. Drilling
fluids cool the transmitter and suspend the drill path cuttings, creating a flowable
slurry.
The
innovative design of the NAVIGATOR horizontal directional drilling system allows
changes in direction during the pilot bore. The angled drill bit and flexible
rod can be steered under, over and around under-ground obstacles. To change the
direction of the pilot bore, the rod is pushed without rotation. When no direction
change is needed, the rod is rotated and pushed simultaneously.
After a
rod is inserted into the ground, another rod is connected to it at the machine
to form the drill string. The drill string bends in response to commands of the
NAVIGATOR operator, allowing the drill head to move in any direction within the
drill rod's band ability.
As with the pilot bore, fluid is introduced through
the backreamer and mixed with the drill path cuttings to create a flowable slurry
which is displaced by the product being installed in the drill path. The backreamer
is sized slightly larger than the product being installed, allowing the slurry
in the drill path to flow freely around it.
A swivel attaches multiple
sizes and styles of pipe or cable to the backreamer. The product is then pulled
behind the backreamer through the prepared drill path.
