El Paso herald. (El Paso, Tex.) 1901-1931, 1918-05-11
.PIST0NSEXERT GREAT INFLUENCE
ON PROPER RUNNING Of The CAR
Expert Describes the Functions Of Pistons and Piston
Rings, Tells Of Their Troubles and How to Over
come Them; Only Experts Should Attempt
to Fit the Piston Rings.
By H. A. TARANTOUs.

4 dONG the subsidiary parts of The
n mechanism OF the automobile en-,
Eine, none is more important or ez.
erts greater influence on satisfac.
tory operation than the pistons and
piston rings. Car owners generally
do not realize this, but, as a matter OF
TACT it is only within very recent
years that the designers and engin-
GERS have begun TO understand the
Importance of the matter, so the
owner need not blush at his excusable
ignorance.
The work Of the pistons is not by any
means a sinecUre. To begin with, the
pistons receive the force of the i'm
pact OF the exploding gases on the
power stroke ana this pressure often
reaches 900 pounds per square inch OF
piston head area Next the piston de-
sceuds on the intake stroke and Gre
ates a vacuum above it. which is filled
DF the new charge Of explosive gas.
And all this must be done in tenn
perature that at times viii run as
high as 800 degrees, T. Obviously.
then, the piston must be made of
sturdy material that viii keep its
shape under the high temperatures in
Vclved- There must not be any sppre-
cable leakage OF gas past the pis-
tons OF the power of the engine viii
be greatly impaired, fuel consumption
viii be increased and, by the same
token. there viii be oil leakage and
carbonization Of the cylinder afflicted
A cylinder may be ukened 10 an in
verted tumbler, inside which are
bosses 10 hold pin or arm 10 which
is attached the connecting rod The
function Of the piston demands that il
shall travel up and down within the
cylinder. This means that il must be
made just a tiny bit smaller than the
inside Of the cylinder. Moreover, the
tendency Of all metal to expand when
heated places very definite limitations
90 the tiEhrness Of the pistou's fit.
But there must not be so much space
between cylinder and piston that the
explosive gas can leak downward. and
the lubricating oil force its way up
from below. To obviate these posi-
1ilitias- the piston is made with a
number Of grooves, two, three. or
even four. In these grooves flexible
rings. having a certain amount Of
spring, are fitted These rings stick
out Just little beyond the surface Of
the piston. cling to the cylinder wall
and consequently keep in the gas and
prevent the oil from making its way
into the combustion cham er-
Best Piston Material
From the beginning of the automO-
bile age until today, many different
materials have been experimental
with IN the attempt TO find the best
piston material At the present time
cast iron is the prevailing material,
but aluminium is making rapid strides
into popular favor Aluminium has the
great advantage Of lightness. which is
more essential here than in any other
part OF the engine. because at this
point the greatest burden OF inertia f.
must be overcome in the beginning
there was q great deal Of trouble with I
the use Of aluminium pistons- The de- I
s. gners have discovered that IL ribs Z
are provided, the heat may be con- I
Quoted away from the piston head ]
and this lighter metal will stand up
as well as the heavier cast iron The ]