The Washington times. [volume] (Washington [D.C.]) 1902-1939, 1924-09-24
~ ERNEST 9. GARLAND,

movement 10 his mentat shift q Al
transfers his foot from the accelera-
tor to the brake pedal.
/ Sul, as niost drivers know, and
as those who do not know should
learn, this is not always good dnlv-
ing. nor safe driving. Stopping a
car on a 10 per cent down.grade at
a given speed is, of course, a great
Ter load upon brakes than stopping
on level at the same speed
i Yet, in cars with adequate brak.
ing systems, properly adjusted. It
Is not merely b question of being
able to stop. We are talking about
good driving, about using our
transportation unit with due regard
to long life and economical main
tenance. -
What, then, is wrong in the prac-
tice Of controlling speed on a steep
down-grade with brakes only?
II one had on his farm or at his
summer home a fifty-foot waterfall
J over which 1000 pounds of water
J passed every minute, the amount OF
waterpower would certainly justif !
an attempt to use it.
Now, an automobile, descending
a 10 per cent grade at twenty mile;
per hour, drops ITS feet every min.
ute. In doing so, one of the weight
OF Cadillac car, for example, de-
velops over three times as much
power as our imaginary waterfall,
over 81 horsepower to be exact.
What becomes of this power? A
small fraction only is necessary to
overcome the friction of the tires
on the road and OF the axle and
wheel bearings. Something must
absorb the remainder.
i Think Of Brakes.
1t is natural to think of the brakes
for this purpose; but let US see. One
would not expect on a level road
to open the throttle, at the same
time apply brakes to hold the car
speed down to twenty miles. per
hour, and drive in this manner for
a mile or more.
Such practice, which any one
would certainly call abuse, would de-
mand no more of the brake than
using them alone to control the car
while descending a long, steep.
What, then, is the correct meth
cd for negotiating such a grade?
Simply to supplement the brakes
with the resistance offered by the
engine while 1t is driven by the
car, placing the transmission in
gear.
The engine is thus transformed
from a. producer Of power to an
absorber Of power.
Using the motor in this way for
braking purposes has become rec
Ognized by engineers as tcchni.
cally correct procedure, and the APP
ENNttsR NJ "A d ut
limited to automomiles.
On electrically driven trains of the
Chicago, Milaukee and st. Paul
railroad, for example, on down
grades the motor is SO used for
braking.
In this case it has an added adj
vantage in that the motor hecomes
a dynamo, and the power nbsorped
Is transformed into electricity and
put back into the line.
In using the automobile engine
for braking, Il should be clear that
| the faster the engine is driven in
relation to the speed of the car.
the greater will be the resistance
offered.
On gradual declines. the resistance
offered by the engine when the
transmission Is in high gear, or d.
rect drive, may be sufficient.
On sleeper grades 1t is hes: to
shift into intermediate gear before
beginning the descent. On very
steep mountain grades, IN which
one should proceed slowly, It is
advisable to shift even into low
gear.
Don't Switch Off.
In using the engine to assist the
brakes, It is natural to think that
it will help still further to switch
off the ignition.
Inconsistent as the statement
may seem, this should not he DONE
Even when the throttle is CLOSED, !"
enough fuel Is admitted to the cyl.
inders to drive the engine at a
speed Of about 800 revolutions per
i minute. II this fuel Is not burned,
1t condenses on the cylinder wall
and washes off the oil by which
the pistons are fabricated.
At the same time, the power
developed by the burning of this
cant compared with the power abb
sorbed.
Switching off the ignition when
/ COdBIi1H, Will TIC car uTlVIuk inc
engine, does not appreciably increase
the resistance, and IL almost sure
to have injurious results. even
though the throttle may be CLOSED. -
In climbing hills. good driving, so
far as the car is concerned Is
wholly matter of engine control.
There Is always a thrill OF achieve
ment in taking a difficult hill ''in
high"
Not All "High'' Good.
Sometimes this is a mark of good
ldriving; sometimes otherwise. There
is tendency among American
drivers to avoid shifting gears. Eu.
ropean drivers, who shift gears on
what we would call the slightest
pretext, find II hard to understand
this American attitude.
Some Of the highest grade multi
ple-cylinder engines have a great
reserve power and can exert an
enormous amount Of II without
detriment. Even in some Of the
lighter cars. in which there II a
favorable power to weight ratio,
good results are also obtained.
However. an plnc6b where deeu