Peterbilt Model 320 Operator's Manual after 8-07 - Peterbilt Motors ...

PART 7: STARTING & OPERATING THE VEHICLE
Driving With Deflated Air Springs
WARNING!
• The rear of a vehicle will drop about 3
1/2 inches (88 mm) when the air springs
are deflated. Ensure that no persons or
objects that could be injured or damaged
are under the vehicle before deflating the
air springs.
• To minimize risk of damage or injury,
do not use a dump valve to deflate the
air springs. Rotate the height control
valve(s) manually to ensure positive
control of air spring deflation.
• To minimize risk of injury, keep away
from air springs as they are being inflated.
3. Rotate the valve either clockwise or counterclockwise
until air pressure in the air springs provides the ride
height specified 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
in "Setting Ride Height").
• 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.
4. 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 "Setting Ride Height").
5. Torque the mounting fasteners to 55 — 75 Lb. in. (6.2
—8.5N.m.).
6. Remove the alignment pin or dowel.
7. Repeat Steps 2 through 6 above for the RH valve on
vehicles with a dual-valve system.
Driving With Deflated Air Springs
If an air spring is ruptured, there will be enough air pressuretodrivethevehicletoasafestopoffthehighwayto
investigate the problem.
R(08/07) Y53-6015 – 103 –