The trailer park brake air supply button
is to the left of the park/emergency brake
button. It must be pushed in to supply air
to the trailer service brakes after trailer
brake lines are connected to the tractor.
The trailer park/emergency brakes can
-
not be released unless this button is
pushed in. See figure 2-3. Pull this but
-
ton out before disconnecting trailer cou
-
plings. (Note that when trailer brake lines
are not connected to the tractor air cou
-
plers, this button will automatically pop
out to prevent escaping air at the open
couplers.)
NOTE: Park/Emergency
brakes are applied
when air is released, and disengaged by
application of air.
2.2.2 Warning Lights for Tractor
w/Hydraulic Brakes
The “brake failure” light operates if either
the front or rear brake systems lose hy-
draulic pressure.
The “high-beam” warning light is acti-
vated when the high-beams are on. A
foot switch toggles “high-beam”.
2.2.3 Warning Lights for Tractors w/Air
Brakes
The “low air pressure” warning light and
buzzer comes on when air pressure in
either tank drops below 60 psi.
The “high-beam” warning light is acti
-
vated when the high-beams are on. A
foot switch toggles “high-beam”.
2.2.4 Instruments
1. The engine hourmeter registers how
many hours the engine has operated. It
is sealed and can record 99999.9 hours
before it returns to zero.
2. The fuel gauge shows the amount of
fuel in the fuel tank. A sending unit in
the tank is connected to the gauge. The
gauge is marked E and F to indicate the
relative quantity of fuel in the tank.
Keep the needle in the green part of the
gauge.
3. The oil pressure gauge indicates oil
pressure only (not oil level). It is marked
6 to 100 with intermediate index marks.
If the gauge registers in the red area,
stop the engine and troubleshoot the
cause.
4. The voltmeter registers voltage across
the battery terminals. The needle
should be in the green area while the
tractor is operating. If the needle regis-
ters in the red while the tractor is oper-
ating, this indicates that the battery is
not being charged by the alternator.
Stop the tractor and inspect the battery,
cables, and alternator connections.
5. The coolant temperature gauge
shows the coolant temperature in the
engine’s water jacket. The gauge nee-
dle should rise when the engine is
started, then level out at between 160
and 200 as the engine warms up. If the
needle goes into the red, stop the en
-
gine and check for a cooling system
problem.
6. The transmission oil temperature
gauge shows the temperature of the
transmission fluid. Normal operating
temperature is in the 120°Fto280°F
range. If the needle goes into the red,
stop the engine and troubleshoot the
cause.
7. The dual air pressure gauge (on the
tractor w/air brakes) has two needles
that registers both the air pressure in
the primary air tank and the secondary
air tank.
PAGE 2-3
NOVEMBER 30, 2005
M200 MB4 Tow Tractor Manual No. 42975
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