TACHOGRAPH (LATE MODEL TRUCKS).

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

20-10. TACHOGRAPH (LATE MODEL TRUCKS).

a. Description. The tachograph is an instrument that has a speedometer,

tachometer, odometer, engine revolution counter, and a 24-hour clock all in one

unit. Inside the tachograph is a paper disk chart that is turned by the 24-hour

clock. Readings of the instruments in the tachograph are recorded on the chart.

The chart must be changed every 24 hours or whenever a truck driver is changed.

Charts must be taken out of the tachograph and a new chart replaced at the end

of each 24-hour period. If they are not, readings will be recorded over a second

time and will be unclear.

Inside the tachograph behind the chart are two lamps that light the scales so

the operator can see them during night operation. Location and function of the

tachograph components are given as follows:

FRAME 1

Lock. Fasten paper disk chart behind instrument face.

Warning indicator. Lights at 2,300 rpm to show engine overspeeding.

Clock. Marks time during 24-hour period recorded on paper disk chart.

Odometer. Shows total vehicle mileage recorded on disk chart during

24-hour period.

MPH. Scale shows vehicle speed recorded on disk chart during 24-hour

period.

RPM. Scale shows engine rpm recorded on disk chart during 24-hour

period.