Peterbilt 320 - Driving with Deflated Air Springs

PART 7: STARTING & OPERATING THE VEHICLE
PB1319 (CAT. NO. 5296 ) —91— 22-01691 (R02/02)
2. Loosen the fasteners mounting a height control valve to its bracket.
3. Rotate the valve either clockwise or counterclockwise until air pres-
sure 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 center-
line of the suspension (see illustration on page 89).
• 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 page 90).
5. Torque the mounting fasteners to 55 — 75 Lb. in. (6.2 — 8.5 N.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 pressure to drive
the vehicle to a safe stop off the highway to investigate the problem.
CAUTION:
• 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.
NOTE: On dual-valve systems, begin with the LH valve on
the next step.
NOTE: At least one of the mounting holes in the height con-
trol valve bracket will be slotted to permit rotating the valve.
WARNING! Your brakes could fail if you continue driv-
ing with deflated air springs. Air escaping from the sys-
tem will lower the air pressure, which could cause a
spring brake to engage. The spring brake may cause
your brakes to drag and burn up the linings. Don’t con-
tinue to operate in this condition.