TM 9-2320-211-20
(15) Long periods of constant speed.
(a) Identifying feature. T h e s p e e d
r e c o r d i n g runs for an unusually long time at a
u n i f o r m level; c o n s t a n t speeds of this kind are
never obtained in practice.
(b) Cause. The speed stylus is prevented
from moving upwards by foreign objects inserted in
the instrument to indicate that lower speeds have
than is actually the case.
been maintained
D e m o n s t r a t i o n of the interference is possible by
calculating the average speed for the period of time
in question (fig. 2 - 2 9 8 ) . It will usually be found
that this appears to be higher than the maximum
speed of the vehicle. In the case of the tachographs
with additional rpm recording, the rpm chart
should also show similar uniform rpm.
Figure 2-296. Coinciding figures.
(14) Distance recordings superimposed.
(a) Identifying feature. D i s t a n c e
recordings are superimposed. Speed and distance
recordings appear to indicate simultaneous
standstill and travel.
(b) Cause. E i t h e r t h e i n s t r u m e n t w a s
opened and the chart turned back (fig. 2-297) in
order to conceal unusually long breaks, or the chart
was in the instrument for more than 24 hours (fig.
s u p e r i m p o s e d . Check the time of insertion and
r e m o v a l . Care should be taken to prevent such
superimposition of recordings.
Figure 2-298. Constant speeds.
( 1 6 ) D i f f e r e n c e b e t w e e n s p e e d recor-
dings. C a u s e : R e c o r d i n g have been filled in by
h a n d (fig. 2-299). These differ from those of the
