Navistar WorkStar Series, Operator'S Manual

Page: 163 / 258

Operation
reinstall the access plug in the chamber opening. Reinstall the
release stud and nut in the carrying pocket on the brake chamber
housing.
Reservoir Moisture Draining
Moisture taken in with the air through the compressor inlet
valves collects in the reservoirs and necessitates draining each
reservoir periodically. This is done by opening the drain cocks
located at the end of all tanks (optional pull-cable-operated drain
valves may be present). If the drain cock is opened in the end
of the tank, there must be some air pressure in the system to
ensure proper drainage. Be sure to close the drain cocks after
all moisture has been expelled.
On vehicles so equipped, the reservoir automatic drain valve
ejects moisture and contaminants from the reservoir in which it
is connected. It operates automatically and requires no manual
assistance or control lines from other sources. The reservoir
should be drained and the valve should be examined periodically
to ensure that the drain passage is not obstructed.
Air Dryer
The function of the air dryer is to collect and remove moisture
and contaminants before the compressed air reaches the air
reservoirs.
This protects the air system components from
malfunctioning including blockage, corrosion, and freezing.
For air tank draining requirements, refer to the Maintenance
Instructions section as well as local regulations.
The air dryer is installed in the discharge line between the air
compressor and the air system reservoirs. The air dryer includes
a replaceable desiccant cartridge and oil blocking filter that is
periodically serviced. It also may include a heater to prevent the
discharge valve from freezing in cold weather.
Trailer Brake Hand Control
WARNING
The hand control valve should never be used
to apply the trailer brakes when the tractor and
trailer are parked. Air pressure may leak from the
system, and the vehicle could roll away, resulting
in property damage, personal injury, or death.
The trailer brake hand control is used to apply the trailer service
brakes independently of the tractor service brakes. The trailer
brake hand control operates a valve that provides gradual control
of air pressure applied to the trailer service brakes. The trailer
service brakes can be fully or partially applied, but when in a
partial position, can be overridden by pressing fully on the brake
pedal.
To apply the trailer service brakes utilizing the hand control,
move the lever clockwise (down).
The further the handle is
moved clockwise, the greater the air pressure applied to the
trailer brakes.
The trailer hand brake handle will remain in
place with the desired brake pressure applied until the handle
is manually moved. To release the trailer brakes, move handle
counterclockwise (up) until trailer moves freely.
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