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4.10 Brake system
Maintenance
Brake system routine checks
1.
Routine checks - I
a.
It is very essential that brake
system is kept trim at all times
and periodic checks are
conducted so that vehicles with
brake system defects are not run
on road. The following procedure
is recommended for a general
check once in 20,000 km. and
after each brake overhaul. For
maintenance data, refer to
specifications.
b.
Place chocks on both front and
rear wheels.
c.
Remove drain plugs and exhaust
all air tanks. Drain water and
assemble back drain plugs.
Deplete air in spring brakes by
applying, releasing hand brake
valve. Keep hand brake in ‘OFF’
position.
d.
Turn vehicle ignition to ‘ON’. The
low air pressure and hand brake
indicators should glow
immediately. The pressure
gauges should read zero. If not,
rectify.
e.
Run the engine at full speed to
charge the system. The air
pressure in one of the service
tanks (the circuit having slightly
lesser opening pressure in the
system protection valve) will rise
at first to a certain limit. Then
other circuit will follow and both
will rise together.
f.
The low air pressure indicator
should be off at the specified
value (5.4
+
0.5 bar). If not, rectify.
g.
Continue to charge the system
till ‘cut-out’ pressure (7.4
+
0.2
bar). The unloader valve should
cut out (identified by a hissing
noise).
h.
Stop engine. The time taken
from zero to cut out pressure
should not exceed specified
pump up time. If it takes more,
check for leakages in brake
system and rectify. Also open
compressor head, check for
defects and rectify.
i.
After pressure in the system
stabilises, the drop in air pressure
(due to leakage if any) with
brakes ‘OFF’ should not exceed
specified value. Otherwise,
rectify.
j.
Apply service brakes and hold.
The pressure in both circuits will
drop by a small amount and
stabilises. The drop in air
pressure (due to leakage, if any)
with brakes ‘ON’ should be
within limits.
k.
Make a few brake applications to
bring down air pressure. When
‘cut in’ pressure is reached, the
compressor charges the system
again till ‘Cutout’ pressure is
reached. Put off the engine.
