TM-5-3805-254-14-P-2
TRUCK, DUMP, 20 TON, 6X4, ON-OFF HIGHWAY 71,000 GVW, IHC MODEL F-5070 (CCE)
TECHNICAL MANUAL; OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT AND DEPT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS INFORMATION AND SUPPLEMENTAL MAINTENANCE INSTRUCTIONS)
JUNE 1980
TM-5-3805-254-14-P-2 - Page 864 of 894
TRUCK SERVICE MANUAL
WHEELS, RIMS, TIRES
alignment.
See "TORQUE CHART" for correct torque
values.
After rim has been properly torqued, it should be
checked for alignment. This can be accomplished by
rotating wheel with a piece of chalk attached to a steady,
firm surface and placed to just barely clear outside
surface of tire bead seat. This procedure will point out the
"high spot". Keep in mind, however, that a "high spot"
does not necessarily mean that lug nuts have been
unevenly tightened. This condition or misalignment can
also result from a bent wheel.
WHEEL AND TIRE BALANCING
Front wheel and tire assemblies must be
balanced to prevent wheel vibrating and bounce.
While
the correct front wheel alignment is necessary for easy
steering and maximum tire life, the cause of unstable
steering can be frequently traced to improper balance of
front wheels.
When this condition exists, the wheel
assembly should be properly balanced.
A vulcanized or retreaded tire, or a tire that has a
boot in it, may cause an unbalanced condition that
cannot be corrected by balancing. In such cases the tire
should be replaced before attempting to balance the
assembly.
Static Balancing
A wheel out of balance statically has a tendency
to bounce up and down resulting in rapid tire wear in
round or oblong spots.
Static balancing is performed while wheel is
stationary by attaching weights to rim flange to offset an
opposite heavy point.
Static balancing may be sufficient in some
instances where vehicle is operated only at slow speeds,
however, dynamic balancing (in motion) balances the
wheel and tire assembly statically as well as dynamically,
thereby eliminating vibrations and wheel bounce at both
low and high speeds. NOTE:
A wheel may be perfectly
balanced statically (not in motion) but may still vibrate
and
bounce at high
speed
rotation because of its being
out of balance dynamically.
Dynamic Balancing
Dynamic balancing is complete wheel balancing
of which static balancing is only a part.
Dynamic balancing (in motion) takes into
consideration the distribution of weight to be added to the
wheel. This is accomplished by rapidly rotating (normal
truck operating speed) the wheel and tire assembly either
on the vehicle or with the wheel assembly removed and
placed on a dynamic balancing machine. This
determines heavy point on wheel.
When the amount of weight required to offset a
heavy part in a wheel assembly is known, it is sometimes
necessary to attach one-half of the weight to the outside
rim flange and the remaining half to the inside rim flange.
With the weight properly distributed on the wheel
assembly, the wheel should be in balance both statically
and dynamically and should rotate free of vibration and
bounce at normal truck operating
speeds.
TIRE CARE
Proper tire inflation, tire loads, and road speeds
are important determining factors governing tire mileage,
and also affect steering ease and maneuverability. How
much these three factors affect tire wear is illustrated in
the paragraphs which follow.
INFLATION
Tire pressures should be checked at regular and
frequent intervals and the pressures maintained to
specifications. Use an accurate tire pressure gauge and
check when tires are cool.
The chart (Fig. 10) illustrates
the loss in tire mileage caused by underinflation. It will be
noted that a tire underinflated only 20% will produce only
70% normal mileage.
Fig. 10
Inflation vs. Mileage
855
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