The sun., 1916-11-19

IN the head has been the return 10 the
uetacnahle cylinder head. With an in
teerai head. valves in the head neces-
state the use Of cages. and these are
not entirely satisfactory. especially In
wnat v come to he known a nigh
e,Mc,ehey engines on account Of diff
neuity or cooling the exhaust valve
u Gagged. Thus one change In design
often leads TO another.
Thermo-siphOn cooling In making
eadwa and is now found on more
than one-third OF all plea sure car mod
els. whereas four years ago its repre-
sentation was as yet only II per cent.
u 10. OF course. particularly prevalent
on the smaller cars. In his connec-
tion Il N interesting To note that thermo-
siphon circulation affords some OF the
advantages which II In now attempted Ia
secure In pump systems by means Of
uhermostatIc apparatus. Thus. upon
STARTING the engine the water will not
begin to circulate appreciabiy until the
cylinders are well heated up. Also the
water continues to circulate after the
engine has been shut down, thus pre-
venting radiato freeze ups in cold
weather.
Lighting n starting systems com.
prisinS two units, working at n pressure
OF elk volts and with ground return
wiring. are largely In the majority.
Thero mas been . remarkable increase
In the representation of two unit sys-
TENS during the last year. which 10 prob
AMY ~oun for by the fact tina the
principal maker Of single unit systems
added a two unit design. and another
very prominent maker who formerly
made both types gave up the single unit
system. or at least ceased to push Il.
FOUR carbureter manufacturers now
divide between them about Is per cent.
Of the carbureter contracts for pleasure
cars. The number OF car manufacture
ers using carbureters OF their own make
has decreased furher.
Battery ignition has nearly doubled
its representation d1sjnt the year. Not
loss than S73.b per cent. Of all cars now
depend entirely on battery current for
ignition. while only four years ago the
proportion was only iks)esr cent. The
so-called closed circuit systems tmagneto
type interrupters) and open circuit sys-
TENS vibrator type i~nterruptsrs) are
so far on about even terms. Vacuum
fuel feed Is now found on n per cent.
of all models.
For quite a number OF years the zone
clutch held Its own against III on
slaughts OF the disk clutch. 1t was en-
tirefy satisfactory in service and It's
simplicity and low cost of construction
seemed to insure 1t a permanent place
In the lower priced class at least. Our
current fluctuations show. however. that
II Is declining In popularity. While no
attempt has been made to divide the disk
clutches into fabricated and dry types.
II Is known that the latter are In the
majority. II 10 possible that the dry disk
clutch lends itself TO specialized manu-
facture better than the cone clutch or.
again. the growing scarcity OF good
leather may have shifted the advantage
to the side Of the asbestos fabric clutch.
There has been a remarkable decrease
In the use Of four speed gears. which
enjoyed something Of a boom -four or
Ave years ago. During the past few
! years the main attention Of designers
has been centred on the ngine and the
latter has been rendered 30 hexible as
to make the advantage Of a four speed
gear over a three IN the average car
practically negligible. However. II is
quite possible that here. too, a number OF
circumstances combined 10 make the
change desirable. and another factor on
posed to the continuance of four speed
gear boxes is the remarkable gain In
! popularity Of unn power plant construc-
ton. A gear box for a unit power plant
must he short. as else the whole unit
becomes too unwicldy. and four speed
gear boxes have only rarely been used
for unit power plants.
Except for a few cars with friction
transmission. bevei gear drive II now
universal in pleasure ear practice
Straight tooth bevel gears are used
mainly on the cheaper cars and helical
bevel gears on the higher priced. though
the latter IL already found on more than
two-thirds OF all the models. There IL
not much change In respect TO rear
axlcs. though the semi-foatlng type has
gained somewhat. mainly AT the expense
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