Peterbilt 579 - Page 222

SUSPENSION
4
• The rear of a vehicle will drop
about 3 1/2 inches (88 mm)
when the air springs are deated.
Ensure that no persons or objects
that could be killed, injured or
damaged are under the vehicle
before deating the air springs.
• To
minimize risk of death,
personal injury or property
damage, do not use a dump
valve to deate the air springs.
Rotate the height control valve(s)
manually to ensure positive
control of air spring deation.
• To
minimize risk of death or
personal injury, keep away from
air springs as they are being
inated.
WARNING!
4. Rotate the valve either clockwise or
counterclockwise until air pressure in
the air springs provides the ride height
specied for
that suspension. Measure
the ride height from the bottom of the
frame rail to the approximate centerline
of the rearmost drive axle hub:
• For tandem axles, make the
vertical measurement at the
centerline of the suspension (see
illustration on
page 4-49).
• For a single axle, make the
measurement in front of the axle,
in the area forward of the tires but
not past the suspension bracket.
5. When at
the correct ride height,
ensure that the height control valve
lever is in the neutral position, then
install either the built-in alignment
pin or a 1/8-inch (3 mm) dowel (see
illustration on
page 4-49).
6. Torque
the mounting fasteners to
55-75 Lb. in. (6.2-8.5 Nm.).
7. Remove the
alignment pin or dowel.
8. Repeat Steps
2 through 6 above
for the RH valve on vehicles with a
dual-valve system.
4-50
Y53-6047–2C (04/13)