Topcon Motorgrader - Page 49

Sonic Tracker II
P/N 7010-0344
2-27
If the Tracker sees an obstruction closer than the reference signal,
such as a grade pin, the sound waves do not take as long to come back
and the stop watch is stopped much sooner. The Tracker is out of the
Working Window, and no On Grade correction signals will be
applied.
Figure 2-34.
STOPWATCH
On Grade
S onic T racker II
T
STRINGLINE
REFERENCE
SLOW BLINKING
CORRECTION SIGNALS
DESIRED
GRADE