St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1919-08-30
SPEED AND 1T PENALTIES,
;(By C.. R, Thomas)

s(By c. R. Thomas)
Vibration is the greatest enemy Of
steel. It causes capitalization, and
by doing so. Weakens the structure
of the steel so that it is liable to
break under any sudden strain, such
as might be caused by "a violent road
shock. The action of vibration is
much greater at high speeds, and so
also is the depreciation of the steel
of whicA the car is built. Vibration,
also, tehds to loosen nuts and screws
whatever their position.
Vibrstion also causes parts to
work against each other unduly. II
the frame members are constantly
working on one another, they stretch
the rivets that hold them together,
enlarge the rivet holes and finally
work free of each other.
The vibration of the engine is part
ly due to road shocks and partly to
unevenness Of power impulse; and
results also. if the crankshaft is
sprung out of true, or If the fiyWheel
is out of balance.
If the fiywheel is not perfectly
balanced the perssue exerted on the
bearings is constantly changing in
directio1 as the f1ywheel revolves,
causing uneven wear and vibration,
which Increases as the speed of reVo-
luton Is increased.
In tour cylinder motor there is a
portion of each revolution where
there is no power impulse. The
speed is kept uniform by the mo-
mentun of the fiyWheel. But the
torque is not uniform, for the crank
shaft is not turning the fyWheel dur
ing this portion of the revolution.
The f1sNneel is turning the crank
shaft and connecting parts. I'm
even forque causes internal vibra-
ton IN shafting, weakening it's
structure.
There is the strain on the crank
shaft Of starting and stopping the
pistons, connecting rods, and wrist
pins twice during each revolution.
At car speed of six and a Quarter
miles, PARTS weighing twelve pounds
are started, speeding up to 1913 feet
inmate, and stopped $40 times a
minute.
In a measure, the parts connected
with che side of the crankshaft bal
ance those connected with the other
side, but they do not act at the same
point pm the crankshaft and the bal
ancing action takes place on the por-
ton Of the crankshaft between the
cranka, exerting continually vary
ing strain, which eventually robs the
crankshaft Of its elasticity and weak
ems it.. Sorce the strains are greater
at high engine speeds. there is more
rapid depreciation of the crankshaft
at high car speeds.
The resistance of the air at high
speeds becomes factor to be reckon
ed with. At very low speeds it is
negligible. At car speed of three
miles al hour, it is three-quarters
of an ounce Fer square foot of sur
face directly opposed to its action;
at twelve miles it is twelve ounces
per square foot; at fifty miles, thir-
teen pounds.
The air resistance varies as the
square of the speeds, if the speed
is doubled, the air resistance Is
quadrupled This is air resistance
due TO car speeds alone. If wind
is bolwing in direction opposite to
which teh car is going, the resistance
offered the cal would be the same IS
if the air were still and the car was
travelling at O. speed equal to the
combined speed Of the car and that
of the wind.
Speed Shortens Tire Life.
Entirely aside from the danger CT
"bloWou:s," whic hare more act 10
occur at higi, speeds, the life OF a
tire is shortened by fast driving.
The tire CT. "a car driven habitually
at twenty miles an hour will ou.-last
two sets of the same kind Of tires,
on the samo car, driven at forty
miles an hour
The portion of the turningg tire
which comes il contact with the road
is slightly hdttened and as it leaves
the road reSumes its former shape.
Thi sconstant bending causes the
layers Of the fabric and the ihers OF
which II is woven, 70 rub t,g sther
creating friction and producing heat.
Neither the cotton of which the
fabric is Wover nor the rubber of
the tire :s a socd coud..c.oc # heat
If the heating effecs is ra,.n. as in
fast dri'.1o, the grea ct po-tl II -:
| he heat IS rot given off t. the air.
| butts aocunl ated in the tire. This
heas ten!: to "er-valc4n;.e he tire,
| hardening to rubber Of the tread
and robbing it of its resiliency. II
the: tread becomes hard and elastic.
| the constant bending which it under
goes, cracks It, permitting moisture
to work into the fabric, and instead
] of FIELDING to the projections of the