Chevrolet DB90 Series, Руководство по обслуживанию

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S ec. 10-1 96
WHEELS AND TIRES
TUBE BREAKS NEXT TO THE VALVE
Im proper inflation procedure may cau se a c ir ­
cum ferential crack or tea r in the valve b a se at the
edge of the bridge w ash er. F igure 14, View A show s
the p osition of bead s, flap and tube with 4 or 5 lb s.
inflation p r e ssu r e . The tube is fully rounded out
within th«! tir e , but the p r e ssu r e is insufficient to
m ove the beads on wide b a se r im s. Depending upon
tir e s iz e and condition of the rim , from 20 to 40
lb s . p r e ssu r e is required to push the beads onto
the tapered bead s e a ts a s shown in figu re 14, View
B .
F orced by th is high p r e ssu r e , the tube can
str e tc h oi|ily in the rim a rea . B ecau se the r e s is t -
retch is g rea test at the valve b a se, ten -
is often enough to crack the tube at edge
ance to si
sion there
of the v a lte base
T his can be avoided by proper inflation p ro ­
cedure a s d escrib ed la ter in this sectio n .
TUBE INSTALLATION
1. Insert tube in tir e and inflate a s shown in
figu re 15, View 1. rounded out. U se approxim ately
1 lb. of aii* or le s s .
2. U sing a b rush or cloth swab, apply a so lu ­
tion of neutral vegetable o il soap in the a rea of the
tir e beadsi, including flap. Do not allow soap so lu ­
tion to rUn down into tir e . Extra ply rated tir e s
may requi|re soap on the rim bead sea t area .
3. Mcjunt tir e on rim , center valve and pull it
through hole in rim and hold firm ly against the
rim . Hold in this p osition w hile inflating until beads
a re p rop erly seated .
4. C om pletely deflate by rem oving valve co re
or using Reflating tool. T his is extrem ely im port­
ant to p resen t tube buckling.
5. R ejin fla te tube to recom m ended p r e ssu r e
(fig. 15, Vijew 2). R efer to "Load and Inflation Table"
at end of t^ is sectio n .
NOTEj U sed flap s may cause tube fa ilu re UN­
LESS mounted with the s iz e tir e and rim origin ally
u sed . When tube and flap a re not properly lubri­
cated and mounted, they w ill be stretch ed thin in
the tir e bead and rim region (fig. 15, View 3). This
w ill cau se prem ature fa ilu re.
A lw ays clean r im s thoroughly to rem ove rust.
C ertain precautions m ust be taken when mount­
ing u sed fla p s, or damage to the tir e and tube w ill
re su lt.
New truck and bus flap s can be u sed with any
one of se v e r a l different tir e and rim s iz e s a s r e c ­
om m ended,
mounted in
But once u sed, the flap m ust be r e -
the sam e s iz e tir e and on the sa m e s iz e
rim from which it w as rem oved. A lw ays u se flap
of adequate width to prevent tube pinching.
A s a precaution against flap fa ilu re, mark the
tir e and rim s iz e on the flap at the tim e of rem oval
- if in sp ection show s that it i s not dam aged and can
be u se d again. When the flap is again mounted, this
m arking p ro tects against the danger of m isusing
the flap with the wrong s iz e tir e and rim .
New flap s and tubes should be u sed a fter tir e
o r rim re p a ir s. It is inexpensive in su ran ce sin ce
sm a ll w ear sp ots and im p erfection s in tubes and
flap s a r e hard to s e e . T his could prevent future
tir e fa ilu r e s.
TUBE RECOMMENDATIONS
1. Long life and high m ileage r e c e iv e d from
p resen t day tir e s exhaust the useful s e r v ic e lif e of
tu b es. T h erefore, when a casin g is worn to the
point of being unsafe, the tube gen erally is in the
sam e condition and should be replaced with a new
one.
2. If valve cap is lo st, clean end of valve be­
fo re applying a ir h ose to prevent dust and dirt
from being blown into the tube. Apply new cap.
3. When tubes a re inflated for in sp ection , they
should not be inflated to the point of "ballooning."
When a tube i s "ballooned," it thins out in the
stretch ed area, making the tube too la rg e in that
a rea and resu ltin g in folds or w rin k les when r e ­
mounted.
SPACER BANDS
INSTALLATION PROCEDURE
1. Check the sp a cer band for con cen tricity,
and a s s u r e y o u r se lf that it has not been distorted
o r bent, or oth erw ise m ishandled in shipm ent.
2. Do not m ove v e h ic le s, w h eels, a x le s, or
a s s e m b lie s by rollin g on sp a c e r s.
3. P la ce the in sid e rim over the c a st spoke
w heel a s far a s p o ssib le up to the mounting le v e l.
4. Push the sp a cer band over the ca st spoke
w heel with a co n sisten t p r e ssu r e on both sid e s .
Guard again st cocking. The band should fit snugly
to the spokes and against the in sid e rim gutter
edge. (At th is point, the concentricity can be ch eck ­
ed by turning the sp a cer band on the w heel.)
5. Apply outer rim clam p s. Tighten clam p nuts
evenly to the recom m ended range, 5/8" studs from
150-175 foot-pounds, and
%”
studs fro m 190-210
foot-pounds torque. Apply torque evenly by grad­
u ally tightening nuts in an alternating pattern a c r o s s
the diam eter of the w h eels.
6. Check to s e e that clam ps do not bottom out,
and be su re the rim ed ges con sisten tly m eet the
sp a cer band ed g es.
7. R echeck torque after a ssem b ly is u sed in
s e r v ic e after 500 and 1,000 m ile s .
MOUNTING AND DEMOUNTING RIMS
For proper p roced u res in mounting and d e­
mounting different type r im s, refer to fig u res 16,
17, 18, and 19 fo r applicable type.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT