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4.10 Brake system
Maintenance
l.
Jack up the rear axle. Rotate
wheels manually. Apply hand
brake. It will not be possible to
rotate wheels. Hand brake
indicator appears on panel.
Release hand brake. Wheels will
be free to rotate again. There will
be a small pressure drop in both
the reservoirs. Now hand brake
warning signals should be off.
m. Lower down rear axle.
n.
Apply service brakes and check
that rear tail lamp glow.
o.
Put exhaust brake piano switch
in ‘ON’ position. Start the engine
and apply brake pedal. Exhaust
brake indication appears on the
panel along with distinct change
in engine noise which indicates
the application of exhaust brake.
p.
Take road test for :
i.
Efficient braking
ii. Absence of grabbing/pulling
to one side
iii. Absence of brake squealing
and rectify defects if any.
iv. Check that hand brake and
exhaust brake are also
functioning properly.
2.
Routine checks - II
In addition to routine checks - 1,
the following checks of different
brake valves keep the system
healthy. It is recommended once
in 40,000 km. and after each
brake overhaul.
2.1 System protection valve
(SPV)
A. Opening pressures
a.
Fail one service circuit say rear
circuit (port 21) by opening any
pipe joints.
b.
Drain the healthy reservoir
(front) below 4 bar and charge
air at max. engine speed.
c.
Note max. pressure in the gauge
of healthy circuit. This is the
opening pressure of SPV port 21,
connected to failed rear circuit.
d.
Repeat a, b and c for other circuit
(port 22).
e.
With all circuits healthy, build up
air pressure till cut out. Open
connector at SPV port 23 to
atmosphere. Pressure in the
service tanks will fall to around
4 bar. Run engine at max. speed
and note the stabilized gauge
pressure (either front or rear
gauge). This is the opening
pressure of SPV port 23.
f.
Repeat (e) for SPV port 24.
B.
Closing pressures
a.
With full pressure in the air tanks,
slowly leak out any circuit, say
rear (port 21) to zero. The
pressure in the other circuit (port
22) falls to a certain value and
stabilizes. This is the closing
pressure of SPV port 22.
b.
Repeat (a) for closing pressure of
port 21.
