Evening star., 1914-01-04

compounds it contains not only are good
conductors of heat, SO increasing the
tendency to heat, but are themselves
capable Of deteriorating the rubber, es-
pecially when heated In service there Is
a natural tendency to heat and the pure
gum tube resists this tendency, being
harder to heat and in addition. is not so
easily injured by heat. This is very i'm
portant in it's effect on repairs. 1t is diff
cult to repair compounded tube salts
factorily. It's adhesion to pure gum yul-
canized repairs is not perfect and the
heat necessary to cure the repair. seri-
ouSly Injuries the part of the tube affect
ed. For short time compounded tube
may give good service. but the pure gum
tube is the only type capable of all
around consistent service.
First of all. the immediate conditions
should be considered. The inside of the
casing should be clean. Ii any dirt is
present, it chafes the tube. weakening it
sometimes to the yielding point. Sup
pose. as often happens. nail or a stone
finds its way inside the casing. When the
tube is inflated. it is fattened against
the inside of the casing by the pressure
and it is forced with equal pressure
against these foreign substances. Fre-
quently they cut the tube before it is
fully inflated. And SO the first requisite
is that the inside of the casing be kept
clean.
Danger of Rim Cut.
Besides the inside of the casing the
tube also comes into contact with the
rim between the beads of the casing.
The rim. accordingly. also should be clean
and smooth. The chief damage from rims,
however. arises from their tendency to
rust. Rust, aside from making the rim
rough. eats into the tube. Perhaps the
most effective way to deal with this is to
paint the rim with graphite paint. When
ever possible this should be done. Flaps,
to be placed between the rim and tube,
offer protection from the rim and rust
and are of advantage, provided the user
is careful not to pinch his tube between
the edges of the flap and the bead of the
casing.
For the repair of punctures and blow
outs it is necessary frequently to remove
the tube from the casing. For this rea-
son the tube should never be permitted
to stick to the casing. something it ordl-
narily has a tendency to do.
Most motorists realize the damaging
effect of running a tire fiat after pune
ture. The casing is quickly ruined be-
yond repair. but the tube is even more
easily ruined. Driving a short distance
with the tire fiat will grind up the tube
into pasty shreds.
Pinching Chief Trouble.
Eve come now to a discussion of the
cause of more tube trouble perhaps. than
all other causes combined-pinching
Again and again the motorist has been
surprised when driving his car carefully
on the best of roads to have an explosion
announce a blowout on one of his tires,
which after his examination proves to
be an internal one. The casing has not
been cut and bruised: it is in perfect
condition. Still. the tube. without ap-
parent cause, has split for the space of
a foot and is worthless.
The cause is to be found in the tires
history short time previously. The last
time the tube was removed from the
casing and then applied again a small
part of it was caught between the rim
and the bead. On being inflated too much
strain was centered at this pinch. The
weakening was gradual but the eventual
blowout certain. Sometimes the blowout
comes more quickly, at time while the
tire is being inflated. The tube may also
be pinched between the spreader at the
base of the valve stem and the stay bolts.
Its effect is the same as a pinch at the
edge of the bead.
Protect Spare Tubes.
Because of the manner in which regu-
lar clincher castings are applied to their
solid rims, pinching at the edge of the
bead is more frequent in the use Of this
type than any other. The elastic bead
must be stretched over the side of the
rim with a tire iron and care is neces-
sary to prevent a pinch. The tire iron
itself, If not carefully used, is likely to
damage the tube. Later, the weakened
spot announces itself by a blowout
"A final precaution will pretty well in
Yv1rt lrc.
and that is this: Protect your spare
tubes. Usually the spare tubes are folded
and carried in the tool box. Here they
come In contact with greases. oils and
tools which present sharp edges. The
tube will frequently be shifted around
during search for some needed article
In time this shuff1ing around chafes and
deeply wears the folded edges. Often a
tube is actually worn out in a tool box
before it is ever used. Tubes should
always be carried in bags or in the paste
board boxes with which their maker fur
niSheS them