New-York tribune., 1918-06-30
Braking, an Ever Vital Topic

ttalnty as to the meaning of this grade,
it should be said that this is slightly
less than slope making with the hori-
zoHtal an angle of 20 degrees. 1t is to
! be distinguished from the surveyors
expression of zone in four" or cone in
ten," which is sometimes enormously
translated into grade per cents, the first
being. enormously called a $3.50 grade
and the other a 1917 grade. Under this
| nomenclature As degree angle con-
stitutes a 100oc grade, and straight
drop, which is in truth 1000 grade,
becomes infnity. This is an error not
lnfrequently made by those who should
be more exact.
1t is general y estimated that above
500 of grade, i. e., 30-degree angle. a
| car would be able to slide down
hill even if it's wheels were locked, and
could certainly not progress uphill, no
matter what its engine power.
The ten feet retardation is equivalent
to $40 grade, making with the hori-
zontal an angle of 18 degrees. A six
feet retardation is equal to a 1877
grade, making with the horizontal an
angle of 10 degrees 30 minutes.
In other words, if the car will stand
without moving when the brake is ap-
piled on hill of approximately 20%o,
its brakes are in fair condition. If it
will stand without moving under SINH
lar circumstances on a 500 grade, it's
brakes are in top notch condition.
The difficulty with both Of these ex-
periments is that on good roads neither
of these grades occur. Even 10 per
cent grade is rare.
Utilizing the method of bringing
the car to definite speed, and the
less speed the better, a single expert
ment will show as we'll as several the
condition of the brakes, if good level
road is chosen. From fifteen miles an
hour, on the basis of ten feet retarda-
tion, with maximum effort with the
brakes, the car should stop within
PAP feet. If the distance measured d
proves to be 1925 feet, it will indi-
cate that only six feet retardation
has been accomplished.
More simple still, if it is possible
to discommode the passengers by put
ting the brakes on suddenly, it is safe
to say that they are not in very bad
condition,
With regard to using the brakes, it
should be remembered that with most
cars both brakes act upon the same
metal, and if they are both applied at
once once there is no opportunity for the
brakes are likely to be ruined. More
over, either brake ought to be sufficient
if in good condition, and therefore the
application of both is unnecessary.
A point not generally thought of
but, recently alluded to by one of the
daily papers is that with some cars
the motion of the springs is such that
on a down grade with an irregular
surface a sudden extra strain may be
put on the emergency brake, if it is
set, which would cause it to break,
particularly with such distractions as
the occasional water channels on back
roads,
When a brake has been subjected to
serious heating. it should be regarded d
with suspicion, as on the next use it
IS quite likely to disintegratc COM
pletely.
In conclusion it may be ar ain
pointed out that quick acceleration and
quick retardation are not the charac
terlstics of good driving, but Of bad.
Both of them are an annoyance to the
passengers and great waste of tires
and gasolene.