Long periods of constant speed.

TM 9-2320-211-20-3-2

(6) Long periods of constant speed.

(a) Problem. The speed field recording shows long periods of constant

speed. Constant speeds of this kind should not be used for long time periods.

(b) Cause. The speed stylus was stopped from moving up the scale by

something being stuck into the tachograph. This will show the truck was moving

slower than it really was. True speed may be found by figuring the average speed

on the chart for the time the tachograph recorded constant speed (Fig. 20-23). The

figure you get will usually be higher than the maximum speed allowed. The rpm field

should also show constant rpm in this time period, but it probably will not.

Figure 20-23. Speed Recording Runs for Unusually Long

Period at a Uniform Level