Pine Bluff daily graphic. (Pine Bluff, Ark.) 1893-1942, 1916-09-24
DON'T BRAKE AUTO
With THE CLUTCH
OF CAR ENGAGED
Transmission Will Suffer If
the Practice Is
Continued.

1t is evident that sudden appn-
cation Of the brakes, applied when
the clutch is engaged and the motor
is fighting compression, is going to
leash against the drive gears, univer-
sals,, gearset and the motor itself with
a strain that is far more severe than
even quick application of power by
opening the throttle wide, according
to Motor Age
With the clutch engaged and the
brakes left alone there is going to
be no harm done to the working parts
if the ignition is cut off or the throt-
tie is fully retarded to create brak-
ing. AS an emergency measure it is
of course advisable to sacrifice the
car to whatever extent it may as a
measure of safety. In such instances
braking with the motor and brakes
in combination is the right thing if
the brakes will not hold the car.
Assuming ideal conditions, the mo-
tor should not be necessary even un-
der such conditions. Brakes should
be so adjusted that they will slip the
wheels, and if they will do this there
is naturally no more braking neces-
sary.
In mountain touring, when one is
obliged to descend great many steep
grades in a day, it would probably be
better to brake with the motor and
brakes in combination than to use
the brakes alone and replace brake
Innings continually. In instances
where brakes are not thoroughly ef-
ficient such measure is imperative
in descending mountain grades to
hold the car under control. The sum-
mary of the whole thing is that it is
inflicting an undue strain on the
transmission units Of car to brake
with the motor and brakes in combi
nation unless in case of necessity.
Shifting Gears.
While still on the subject of driv-
ing it might be we'll to remind those
who have become careless in shifting
the gears in their cars, that continu-
ed slashing of gears in and out and
shifting with the motor turning at the
wrong speed in relation to the speed
of the driveshaft, is practice that is
as harmful to the car as skidding or
continued high speed over rough
roads.
AS an example, take car with 30
inch wheels having gear ratios Of a
to l on high, 8 to l on intermediate
and IL to l on low. Assume that
the car is travelling at a constant
speed of five miles an hour. The fol-
lowing table results:
Revolutions a Minute.
Wheels. Shaft. Motor.
Low 80. .... Sc 224 672
Second 80. ....... Sc 224 AS
High go. ............ Sc 224 224
From this table it can be seen. that
the car with the specifications as
sumed, when travelling five miles an
hour, will have an approximate motor
speed of 672 revolutions minute with
the car running in low gear. In shift
ing from low to intermediate the motor
speed should be reduced one-third. In
intermediate the motor speed will be
approximately 448 revolutions min
ute. Then, in shifting from inter-
mediate to high the motor speed must
be reduced one-half.
The wheels, travelling at Sc revolu-
tions a minute. are revolving on a
solid surface and will permit no slip
of enough account to relieve the
strain on the motor. On low speed the
motor is revolving just twelve times
this fast. An engine speed of 672
revolutions a minute gives the power
plant considerable momentum. Sup
pose that the gears are shifted into
intermediate and the throttle is held
open to maintain the engine speed at
672 revolutions a minute, then the
clutch is suddenly dropped in. The
motor speed must instantly be re-
duced a third. It is like striking a
brick wall with your bare fist with all
your might. Your fist is bound to
suffer.
1t is we'll worth the thought to take
the foot off the accelerator pedal
when shifting to a higher gear. In
the same line is shifting Of gears
without the car, having been given
sufficient momentum.