New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1917-10-21

Valve-in-Head
All Explained
Corridor and Window
Smile Makes Engine
Types Clear

bile sellers, in advertising or sales tall
One of the famous objections wa, !.
the description Of engipes as AZ head
1T" head or "valve head" witbnn,
telling what the names meant. Il !,
in keeping, therefore, TO reprint fror
THE Chevrolet Review part Of an
article that tells clearly just what ths
three types of engines are.
We disclaim IA not our own N.
favorable opinion Of the "yalyeIr.
head" type. 1t is found in the Ch,v.
rolet car, hence. readily enough. IN.
high praise. The article is one n
which "Haskins" tells Brown ali
about it. "Haskins" is talking:
1.-THE reason for these three nams,
designating these three types lies h
the arrangement of the 'yalyes'-th.
inlet valve, which admits vsporizes
gasolene TO the cylinder, and the ont.
let valve, which expels the burned
residue gases from the cylinder after
explosion.
You know the normal operation q,
any gasolene motor is fairly simple.
fresh charges or mixtures Of airanS
gasolene are drawn from the car.
buretor into the combustion chamhe,
OF the cylinder BY the suction force
exerted by the moving pistons-jus,
as air Is drawn into a tire pump by
F, the suction action of its plunger.
This charge enters as the piston
goes down; when it comes uD, due "a
the turning of the crankshsft, it com.
presses this vaporized gssolene Just a,
you would squeeze ball of paper in
your hand. When this gas has beer
squeezed into its highest package BIZ
the rising of the piston an electric
spark jumps from one terminal Of the
spark plug to the other about one.
sixteenth of an inch, usually and this
spark ignites, or explodes. the highly
infammable gasolene vspor
What happens? An instantaneou.
expansion of the gas. due 10 the ter.
rifle heat generated (the temperature
actually jumping from 300 degrees 10
$500 degrees Fahrenheit. This ex.
banded gas tries in every direction to
escape from the cylinder. SO ire.
mendous is this expansion-force that i,
is like the shock of a dynamite ex.
plosion in miniature. and il takes place
constantly inside the motor; but, be-
cause these explosions are unseen and
prisoned in the cylinder walls. We car
owners never give them passing
thought.
"The only avenue of escape, then, for
this titanic force is by pushing down
the piston-head, the one movable OBJ
ject against which the impact falls.
| This thrusting down of the piston
communicates turning power 10 the
crank-shaft, which in turn passes II on
to the drive-shaft, and thence the force
/ travels to the rear wheels. which move
/ the car. Now, this operation is COM
mon to any type of motor OF the three
types most in use by manufacturers
Brown-Then what difference does
/ L-head, T-hesd or valye-in-head make?
Haskins-"I was just coming 70 that
| The best illustration of the arranging
! of the inlet and exhaust valves in these
different types is that Of a hotel cor.
rider. with rooms on both sides and
4 room directly at the end Of Il, whose
| door faces down the hall The hall IL
self represents the cylinder OF the
/ motor.
"Now. the L-head type Of motor Is
! symbolized by imagining the last roo'
| on the left-hand side Of the hall
/ having it's door open and two Windows
placed on the further side OF me
room. This room represents me wave
1 chamber or pocket, as automoolle men
call it, and its two windows the intake
and exhaust valves. Suppose you want
to bring air into the hotel corridor
! through this room. The air must come
in from one of the windows OF me
room. pass through the room ITSELF
and then turn at right angles 10 PASS
on into the hall. A long, roundabout
course, isn't IL?
"The same thing happens in an L,
head motor. The gas or vapori1ed
gasolene charge, must come in through
the inlet valve into the valve chamber
where it is exploded by the spark
plug; then the lines Of force must
twist themselves around into the eylln'
der before they can act on the piston
and push il down"
Brown-That's like the old phrase
around Robin Hoods barn." isn't y!
Haskins-"It sure is. II simply
means that some of your explosion
force, some of the energy originally 10
the gasolene, is lost before 1t can De
used"
Brown-What about the T-he'd
then?
Haskins-"In T-head a similar thirf
happens. Only in this second yP
of motor you open room dooI
directly across the hall on. tae
right-hand side and use WINDOW
in the opposite wall, shutting one
of the windows in the room ."
your left-hand side. You now have
room and window on each side OF Sno
hall, or, in motor language, sa'N
chamber and a valve on eacn slue
the cylinder-inlet valve and chsmS.,
on the left, exhaust valve and enanO''
on the right" II :,
BrownEThat's why they call
T-head. suppose; it's shaped lu'' III"
the letter T. l-,,. "a,
route of the gas in this type OF plo,Ga
IL comes in through the valve on inc
left. goes into the valve chamber, Is eA.
ploded by the spark plug. and the ioi'.
lines have to twist around the cyilhos.
"a before Gin the L-head). wnle IN.
dead gases left after the explosion rus.
he showed out through the eNnsos.
chamber on the right, and tnen.'
through the exhaust valve. by the pr
ton on it's next upward stroke III.
again. there is force lost m the touna
about movement Of the gas. from w.
time il enters the window on the lsn
until il is expelled through the roo@
at the right. and out OF the "In'0'
on it's opposite side. -. IN.
Brown-That's no better tnah VIZ
L-head. is II? -. a,
Haskins-"As a matter Of iaeb w.
several per cent worse. But, have ~,
got those two types clear in your in'"''
now" 80. lea,
Brownies, | have. But let's ne"
about the I-hesd type. -
Haskins -"All right 'NalVe-ln-h..sS,
is the usual terni. though. It's exssm
what the name implies, too, fno..
with the inlet and exhaust valves nt
=. - LaaJ a., ton of the cylinder. Wv