Backreaming And Pullback - Toro 2024 Operator's Manual

When drilling, the receiver operator follows the drill head as it
progresses. The receiver receives signals from the sonde in
the drill head identifying its position, depth, pitch, direction,
transmitter temperature, and orientation in the soil. The
remote console is a screen that remains near you (the drill
operator) to show you the information from the receiver
while drilling so you can make steering decisions.
For detailed information on using the receiver and remote
console to guide the drill head, refer to the Operator's Manual
that came with your receiver.
Important: Do not steer the drill head more than 20 cm
(8 inches) off center for every 10 feet of forward travel. If
you steer more than this you will damage the drill pipes.
Boring the Horizontal Shaft
After creating the entry shaft, you gradually steer the drill
head up while pushing forward, following the planned bore
path. When you reach the desired depth, level out the drill
head and bore the horizontal shaft, adding pipes as you go.
While boring, pay close attention to the information relayed
back to you by the receiver operator about the status and
location of the drill head to ensure that you are following the
planned path.
Important: While drilling, watch the sonde temperature.
All sondes have a maximum temperature above which
they will be damaged. Friction between the drill head
and the soil will cause the temperature to raise. To
reduce the temperature, slow down, decrease forward
pressure, and increase the drilling fluid flow. If the drill
head is entering a soil type other than what it is designed
for, that can also raise temperature. Assess the situation
and pull out the drill head and change it if necessary.
If you run into an obstruction, do the following:
1. Increase the flow of the drilling fluid for a few seconds
without drilling, then attempt to continue drilling
forward.
This may loosen the obstruction and allow you to push
past it.
2. If the obstruction persists, try one or more of the
following options:
•
If the obstruction is in an area where you can dig,
stop the drill head with the Exit Side Lockout
and dig down to the obstruction to identify it and
remove it if possible.
•
Pull the drill head back 15 m (50 ft) or more and
steer the drill head to the side, marking a new drill
path around the obstacle.
Important: Do not steer the drill head more
than 20 cm (8 inches) off center for every 10
feet of forward travel. If you steer more than
this you will damage the drill pipes.
•
If the obstruction is actually a change in soil types,
such as a zone of rocky soil, pull the drill head all
the way back and change to a drill bit appropriate
for drilling through the new soil type.
Exiting the Ground
As you approach the end of the bore, steer the drill head to
the exit point, keeping the steering limits in mind as you do
so. Before exiting the ground, ensure that everyone is away
from the exit point. As soon as you break through, stop the
drilling-fluid flow. Extend the drill forward until the entire
drill head is out of the ground.

Backreaming and Pullback

After drilling the initial bore, you attach a reamer to the pipe
which is then connected to a the product you are installing.
The reamer is designed to widen the bore, pack the walls and
lubricate the passage of the product into the bore.
The following reamers are available from your Authorized
Toro Dealer in various sizes to meet your needs and soil
conditions:
•
Carbide step-wing cutter—Use this reamer in sandy
and medium clay soil conditions to mix the drilling fluid
with the soil, making a mixture that flows easily around
the product being pulled.
•
Cast cone packer—Use this reamer in soils that pack
easily, such as soft clay, peat, and loam, to pack the sides
of the bore, maintaining the bore opening.
•
Fluted reamer—Use this reamer in hard clay and rocky
soils; it combines the features of the other two reamers.
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