TM 9-2320-211-20
downwards. W h e n the vehicle is stationary a
(5) Record of distances traveled. The distance
stylus registers the distances covered, and also
concentric base line is recorded. The base line must
run at a given radius; otherwise the recording will
distance with respect to time. Complete upward
not correspond to the actual speed of the vehicle.
a n d downward arcs correspond to 10 miles or
kilometers. Pauses between distance are registered
lines. If the base line does not fall within this range,
as concentric lines. To enable accurate readings to
but lies below it, it is possible that the stylus was
be made, the recording field itself is divided up by
bent down to indicate that the vehicle was driven
concentric circular lines (fig. 2-280); the distance
more slowly than it really was.
between each 2 lines corresponds to exactly one
mile traveled. At the same time the speed stylus also
marks the outer time graduation or the graduation
below this line as indicated in (3) above.
Figure 2-278. Speed recordings.
(4) Traveling and stationary times. The time
(vibration) stylus marks the vehicle traveling and
stationary times. The recording mechanism consists
of a simple oscillating pendulum kept in balance by
a spring. When the vehicle is in motion, the
vibrations of the pendulum are trnasmitted to a
(6) Engine rpm. In addition to speed and
stylus. The stylus is deflected through a given width
traveling and stationary periods, engine rpm is also
and in the case of an extended journey the recor-
recorded. It is recoreded simultaneously on the
ding takes the shape of a broad, red band. The
reverse side of this chart. The recording field for
vibrating pendulum is in fact a simple form of
engine rpm is also divided up by concentric circles.
seismograph which records all vibrations of the
This enables the viewer to read off accurately the
v e h i c l e independently of the tachograph drive
rpm reached at a given time. Various rpm ranges
mechanism. This recording will remain unaffected
a r e available. The recording is not made in a
b y a faulty drive m e c h a n i s m o r a b r o k e n o r
straight line, but in an arc. The time graduation is
disc onnected cable (fig. 2-279).
related to the base line and the maximum rpm
measuring range. Unlike the speed diagram, the
base line is recorded immediately after inserting
the disc and not only when cover is closed (fig. 2-
