ASTEC RT130, Operator'S Manual, Page: 25 / 64

OPERATING INSTRUCTIONS
21 AU106984 G7B
Boom Position When Digging
For the best digging performance and smoothest machine
operation, the boom must be in the full down digging
position. In this position, the machine is pulled down for
better traction. The ground drive simply pulls the digging
teeth into the face of the trench.
When the boom is raised from the full down position, the
digging load pulls the machine more rearward. This
pulling reduces traction and may cause the machine to
bounce and pull when the chain contacts roots or rocks.
The rearward pull of the digging operation also works
against the ground drive causing the machine engine to
work harder.
TRENCHER CHAIN AND TEETH
Chain
The correct chain for the job is very important. Soil
conditions determine the type of chain. A chain that is too
light will wear fast or break. A chain that is too heavy
increases the load and slows the trencher speed.
Digging chains are rated by tensile strength. For example,
a 34,000 pound (15,422 kg) chain takes 34,000 pounds of
pull to break.
IMPORTANT:
Correct chain tension is very important.
See CHAIN TENSION in this manual.
T560110
Chain Tension
If you adjust the digging chain too tight or too loose, the
digging efficiency of the trencher is decreased and the
wear of the parts is increased. See CHAIN TENSION in
this manual for correct chain adjustment.
NOTE: When digging in extremely hard ground, remove
all deflection from the chain. Remember to adjust the
chain for normal digging conditions as soon as possible.
Teeth
The most important parts of the trencher are the teeth.
The type of teeth that you select and the arrangement
you use makes a big difference in the digging efficiency
and tooth life.
Always keep good sharp teeth at the correct positions on
the trencher chain. This will increase the digging
efficiency of the trencher chain. Replace immediately any
digging teeth that become worn.
When making digging tooth arrangements, follow these
instructions.
1. Digging teeth, that are the same width, must be put
at equal spaces around the chain. This procedure is
necessary to have a balanced digging chain.
2. When digging in wet clay or gumbo, it may be
necessary to have less teeth on the trencher chain. A
chain with too many teeth can become filled with soil.
This will increase the drag and decrease the efficiency
of the digging chain.
3. When digging in hard soil, rock or sandy loam, it can
be necessary to install more teeth on the chain. This
will increase the efficiency of the trencher chain.
4. Install teeth in the proper sequence and repeat the
sequence until the chain is complete for the most
effective digging.
5. The conditions shown in the following illustration
cause rapid wear of the chain, teeth, and sprockets.
To stop this problem, decrease the ground speed,
install more digging teeth, or both. In sand or very
loose soil, install dirt drags.
RT160034
WARNING:
Make sure all people are clear of the
machine and working area while the digging chain
is rotating. Serious injury or death can result from
contact with the digging chain or flying debris.