Specifications

17730-248 31 Preventive Maintenance
AIRTEK
®
•
SOFTEK
®
for Blue Bird Buses
FIGURE 7-13
Diagonal Wear — Can be described as localized flat spots worn
diagonally across the tread at approximately 25-35° angles, often
repeating around the tread circumference. For more information, see
TMC RP 219A publication, page 20.
Diagonal wear is usually caused by bad wheel bearings, toe out,
mismounting of tire and wheel assembly to axle, and mismatched
duals for size and/or inflation pressures. It may start as brake skid.
Diagonal wear is aggravated by high speed empty or light load
hauls.
To correct diagonal wear, reverse direction of rotation of the tire. If
wear is excessive, true tire. If the source of trouble is the vehicle,
diagnose cause and correct as needed.
FIGURE 7-14
Rapid Shoulder Wear (One
Shoulder Only) — Is defined as a
tire worn on the edge of one
shoulder, sometimes extending to inner ribs. It can
progress to diagonal wipeout. For more information, see
TMC RP 219A publication, page 22.
This wear condition is usually caused by excessive toe
or excessive camber. These conditions can be created by
a misaligned or bent axle and can also be caused by loose or worn wheel bearings.
To correct this type of rapid shoulder wear:
■
Tires – Change direction of rotation of tire. If shoulder wear is severe, remove and
retread.
■
Vehicle – Diagnose misalignment and/or mechanical condition and correct.
FIGURE 7-15
One-sided wear — Is excessive wear on one side of tire
extending from the shoulder towards the center of the
tread. For more information, see TMC RP 219A, page 26.
One-sided wear is usually caused by improper align-
ment, worn kingpins, loose wheel bearings, excessive
camber, excessive axle loads, non-parallel axles, or
non-uniform tire and wheel assembly caused by
improper bead seating or bent wheel.
To correct one-sided wear:
■
Tires – Depending on severity, rotate tires to another axle position or, if worn to
minimum tread depths, submit for possible retreading.
■
Vehicle – Diagnose mechanical problem and correct.
SERVICE MANUAL
L
73
FRONT AXLE & SUSPENSION
1
APPENDIX