TM 5-3825-226-24
PARKING BRAKE CONTROL VALVE
LOCATION OF CONTROL VALVE (TREADLE)
ELECTRIC WARNING SYSTEM
The buzzer (3) is a warning of low air pressure.
The low air pressure indicator (6) makes a
measurement of air pressure in the brake air
system. The low air pressure indicator is closed
(current flows and the buzzer sounds) when the air
pressure is below approximately 60 psi (415 kPa).
The buzzer is located under the dash.
ELECTRIC WARNING SYSTEM
1. Pin connector. 2. Ammeter. 3. Low air pressure
warning buzzer. 4. Circuit breaker. 5. Low air
pressure buzzer located under the dash. 6. Starter
switch.
PARKING BRAKE
PARKING BRAKE
The parking brake activates automatically when the
air pressure in the line to the parking brake control valve
goes below 40; psi (280 kPa).
Pull on the knob for the parking brake control valve
to open the valve and activate the parking brake. Push
on the knob to release the parking brake. Air pressure
in the line to parking brake control valve must be 50 psi
(345 kPa) minimum for the valve to stay closed.
EMERGENCY BRAKE
The emergency brake activates automatically when
the air pressure in any of the three lines that go to the
emergency section of the control valve (treadle) goes
below 50 psi (345 kPa).
EMERGENCY BRAKE CONTROL VALVE
The service brake caliper heads and master
cylinders are used for the emergency brake. Pull on
the knob for the emergency brake control valve to
manually activate the emergency brake. To release
the emergency brake, air pressure in all three lines to
the emergency section of the control valve (treadle)
must be 50 psi (345 kPa) minimum and the knob for
the emergency brake valve pushed in.
2-130
