BRAKES
Service
brakes
The vehicle is equipped with a dual braking system,
tront brakes being independent
of
rear brakes. This
brake system becomes a modulated system if a pres-
sure
drop
occurs in the rear brake system.
Service brakes are applied
by
depressing brake treadle
located to left
of
accelerator pedal. The degree of foot
pressure applied to treadle determines extent of brake
application. For best braking action, initial application
should gradually
be
increased to required
rate
of braking;
foot pressure should then be gradually reduced as
vehicle speed is reduced so that only slight pressure
remains
in
brake chambers when stop is completed.
When brake treadle is depressed, vehicle stoplights
automatically light up.
For safe brake effectiveness, vehicle air system pres-
sure must reach at least 85 psi (585 kPa)
in
both
primary and secondary circuits.
In
normal operation,
if
air pressure in both brake sys-
tems drops below
40
psi
(276
kPa), spring loaded
emergency parking brakes will immediately be applied
at full capacity to rear axle to stop vehicle. Cause
of
pressure loss should be determined and corrected
before proceeding.
A «low aim indicator light is designed to
go
on
and a
buzzer to sound when air pressure in one
or
both
systems drops below 65 psi ( 448 kPa). Vehicle should
be stopped and problem reported to maintenance
personnel.
•
WARNING:
((Fanning»
or
«pumpingu brake pedal
is not recommended. This practice will not increase
brake system effectiveness but will instead waste air
and cause unnecessary wear
on
brake parts. uFan-
ning»
or
((pumpingn does not increase brake
li
ne pres-
sure but decreases both reservoir and
li
ne pressure.
cc Riding» the brake by resting foot on brake pedal even
when not braking can cause abnormally high brake
temperatures,
excessive
tining
wear and possible damage
to brake
drums
.
Parking brake should always
be
app
li
ed when vehicle
is
parked.
Parking
brakes
The vehicle is equipped with spring loaded parking
brakes. Control valve knob is located at left of driver's
seat, on the small control panel.
2:8
Spring loaded parking brakes are applied
by
pulling
up control valve knob. Parking brakes should always
be
applied when vehicle
is
parked. They are not designed
for use in normal braking: when vehicle is moving
under normal conditions, control valve
knob
should
be pushed all the way in. On the other hand, parking
brakes can supplement service brakes to stop the
vehicle in an emergency.
Before releasing parking brakes by pushing
down
con-
trol valve knob, air pressure gages should
be
checked
to make sure that brake system air pressure has built
up
to a
minimum
of
85
psi
(585
kPa).
Emergency
brakes
In
normal operation with full air pressure, if normal
application
of
service brakes should fail to stop the
vehicle for any reason whatsoever, emergency brakes
should be applied by pulling the parking brake control
valve knob. Spring loaded brakes will be applied to the
drive axle.
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