User Manual

Table Of Contents
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1. Normal Run Position
2.
Trailer Park with Vehicle Released
3. System Park or Trailer Charge with
Vehicle Parked
To apply the trailer brakes only:
Pull OUT the Red knob. This will exhaust
air from the trailer supply line, causing the
vehicle protection valve to close and the
trailer spring brakes to apply
. The trailer is
now in emergency or park. This mode
would be used to uncouple from the trailer
(running without a trailer connected).
WARNING
Using the trailer hand brake or air
brakes
to hold a parked vehicle is dan-
gerous. Because they work with air
pressure, these brakes could come
loose. Your vehicle could roll, causing
an accident involving death or person-
al injury. Always set the parking
brakes. Never rely on the trailer hand
brake or truck air brakes to hold a
parked vehicle.
System Park
With both knobs pushed in for normal
operating modes, the parking brakes of
both the vehicle and the trailer may be
applied by pulling the Yellow knob OUT.
This will exhaust the air from the vehicle
spring brakes, and simultaneously cause
the Red knob to pop OUT, which will apply
the trailer brakes. This complies with the
Federal Motor V
ehicle Safety Standards
(FMVSS) 121 requirement that one control
should apply all the parking brakes on the
vehicle.
Trailer Charge
If both knobs are OUT (combination
vehicle is parked), and it is desired to
recharge the trailer, the Red knob may be
pushed IN repressurizing the trailer supply
line. The vehicle will remain parked. For
more information on air supply pressure
requirements, see Initial Charge on page
138.
Trailer Brake Hand Valve
This hand valve provides air pressure to
apply the trailer brakes only. It operates
independently of the foot treadle valve.
To operate the trailer brake hand valve:
Pull down on the lever under the
right side of the steering wheel.
The valve is self-returning. When
pressure is removed from the valve
lever, it will return to the OFF
position.
DRIVING - Air Brake System (option)
Trailer Park or Emergency Brake
Application Only
If you ever have a failure or disconnect the
air supply hose to the trailer, the trailer
parking brakes will set. The Red knob will
automatically pop OUT and seal off the
vehicle air tanks to protect the vehicle air
system pressure.
Y53-6113-1A1 (11/20) 139
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