Evening star. [volume] (Washington, D.C.) 1854-1972, 1923-04-08
IMPERFECT BRAKE
SERIOUS MATTER
Proper Adjustment Means
Much to Autoist in Mat
4 ter of "Safety."

A large percentage of motorists are
driving. according to the Asbestos
brakes, according to the Asbestos
Brake Lining Association, national
organization of manufacturers. which
Is conducting an educational cam
paign to induce drivers to MAINTAIN
brakes in reasonably efficient con-
dition. A statement just issued says
that 1t seems worth while to point
out some of the more important fac
tors in this matter of brake adjust
ment but first takes up some Of the
causes Of failure.
First and most important is wear
on lining. Clearance between lining
and drum will vary from OPS" to to
.050" This clearance is measure
Of the efficiency Of the operating
mechanism, or hoOk-up. II the
clearance Is hut OPS" and the advan-
tage of pedal pressure is II to l,
as on many external brakes. provided
there is no lost motion at any point
due to wear or clearance on bearings.
rods, etc, movement of 1.65' VIII
set the brakes.
BY actual test on car the travel
is three inches when the clearance
is OPS" This brings the pedal with.
in one inch of the floor board and
wear of .0lO" on the lining means
that 1t is no longer possible to in
crease the effective pedal pressure.
Wear or Compression.
Ten thousandths wear or compress
sion on the lining means an adjust
ment and the driver usually gives the
wing nut on the upper side of the
band half turn. or possibly a full
turn, but frequently fails to touch the
adjusting nut on the lower end of
the band and very seldom considers
adjusting at the anchor end.
Where close adjustment Is required
1t is very important to maintain 1t.
and when this Is made at one point
only, as at the wing nut, 1t Is quite
possible that the full wrapping ef-
feet of the external may be entirely
lost, and the upper part of the band
may be the only portion working.
This means not only less efficient
brakes but rapid wear on a portion
of the lining and no wear on the
rest.
When the lining wears down ops"
or more 1t is necessary to readjust
at the anchor stud. otherwise the
rear half Of the lining will not do
it's work and we shall have excessive
wear at the ends of the band.
Equalizers fail to equalize when
there is any considerable difference
in clearance on the two drums.
1t Is important. therefore, to make
adjustments on the band rather than
on the pull rods.
If adjustments is made by shorten
ing the pull rods. the actuating lever
will be pulled forward and the effect
sof moving it becomes greatly DIM
finished.
The actuating lever should be in
n nearly vertical position when the
brakes are set.
Varying Mechanical Advantage.
Some cars have adoption for vary
Ing the mechanical advantage at the
pedal. This variation Of mechanical
different positions on the pedal. At
tachins nearest the pedal bearing
gives the greatest mechanical adj
vantage, but requires much less
clearance or closer adjustment of
Some drivers demand effective
braking at low pressures and this
can be obtained by attaching the pull
rod in the position nearest the pedal
bearing and adjusting the bands to
a clearance of 900"
It will be found impossible to do
this In many instances because of &c
centric drums The clearance must
be greater than the eccentricity,
otherwise we have a. dragging brake.
1t is common practice to lay failure
of brakes to the lining. Lining diff
fers greatly in durability. but there
efficiency at ordinary braking tenn
peratures Lining, Of course, must
be renewed when brake adjustment
can no longer take care of wear, or
when metal is bearing on the drum
instead of lining.
Briefly, external band brakes fall
In efficiency when improperly ad-