Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1920-01-11
AUTO LESSONS !
GUERRLlCH TELLS HOW TO
STUDY SPARK PLUGS FAULTS
Engineer Expert Explains. In Nom
technical Terms, interesting Fen
lures OF Device.
BY FREDERICK &. GUERRLlCII, VI. f..
Lesson No. f.N.

very large proportion OF missing
ana irregular running @! the aut" en-
The action OF the engine. when there
is tanitY spark plug. is. however
very similar to the action when there
a test only will tell which is at fault
In studying the faults Of a spark
plug, let us first see what its action
is. and how the spark is. formed.
In the illustration a is the body OF
the Plug, which is screwed into the
an excellent electrical contact that is.
passage Tor the electrical currently with
~. y is OF nonconductinS material.
through which the current cannot so
from the rod c 20 the body Of the plug
& is a rod 10 which the electric wire is
while L. also called an clcctrode. is a
hSaNy wire attached to the body OF
plug. The space between tho cleo
trodcs. is called the spark gan
Compares with Flow Of Water
You were ;oId previously that the
flow OF an electric curren; can DO
comnared 20 the How OF water. the
TWO acting very much tho same, and to
: large HN;eut following the same
avs % nature, Thus il requires a
pressure (CSllcd VOLTAGE TO make
electricity dow through a Wire iust
- i does 10 make water flow through
study for = moment Fig. > Here
E";eF could now through The pa ssases
u !. were Il not Tor IN. small por-
ION w OF the containing material. II.
!Laue we're not Very strong, then III the
pressure q: The water w,r. nr.u.iy
raised. eventually tA.s pressure wouil
ne 50 great as ~ cause The u,Aterigl a.,
burst through
II " De made ia.ckcr. +, would re.
water 10 hurs, through This Would
also be tue i tho ua;erla, we're
Asain. il the ceatainins material 6,
some point say l, were 10 6nTeio, q
era or or wea"ness at This Poin. than
Compare now Fig. / and . Does
3ot TIE air space. around + in Eis.,I
S Sais Is rs. nso,n,;conduc,oT 81 electTc:tF)
porcelain d OF the plug. and III. al
around the bottom OF the electrodes
n Ds;ow sh e, porcelain: appear to make
II and &, Just as thc matcrisi Of
rig. makes the passage T. Y and =
electric current DO steppci b. .hc s .iS
o. INC zap /. Just Is the now Of III.
WW9'eT Is stoppcd b tho matcrisl Of
through the ar space. or MI, .r.m ir,,,
pressure COR VoltaE"l is htgr .nn,,-b
5Tr'I as the water viii burs. ;hroISh
Now; when the ci.ctric ''y"' bursts
be be- eenera an a., ian " 10, SpariS win
ar can be distinctly heard. You b,vc
9lten. seen this action during :, ;hun-
,-5,norah INC c.ectric!t~ Which has
Eathercd on the clouds ;rics 10 nv,
rom one 10 the other. and is prcvcntn,i
"S me air between but as the clouds
,S S;i,1n cioSer together the mir becomes
Sn'nhcr ana too weak to resist IL. anI
s n,- me ne, eisctririty bursts through. civ
hear the "crackirc'' o. ms, "iu YOU
thunder. Wv - "a tNc
Thus. We see tina; when cu-rnpt ~
L't5n-NoitASc 'priSSurcl clcctriciiv js
Sent through the wire T. 10 Tho snori,
5,'us ! VIII pass through the rIrc,rodc
ana then jump the air gan r. Twin.
ne required SPARK n il docs so
LEI us see what TROUBLES" the srarl;
pug Is subject to. First OF au -,
now that 1t required a high voltage
make The current jump HE gap. s.
nc No!laGc or magnetic or generator
Is dependent upon tho speed of it's ar.
mature. hut comparatively low volt.
aSe is generated when the engine is
being cranheG. which voltage is often
100 low TO give. spari. Thus. with
many system of ignition, ana cspcci,