Evening star., 1912-11-05

beginning to be believed that a man can
not work as well with noise dinning into
MS ear as he can in reasonably quiet
surroundings. This is the more readily
oelleved when we recall that the shop,
off1ce and drawing room-places where
brains are supposed to be active-are usu-
ally secluded and kept quiet The book
keeper and craftsman must not hear
noise OF the shop, such Is the general
attitude.
'One shop manager refused to use
pneumatic hammers in his shop because
or his belief that they result in loss
OF efficiency through the distraction of
workmen. But still further the way has
been shown toward designing noiseless
machinery by the automobile Who
knows but what this may be one of its
greatest blessings? The public demand
for quiet-running cars has made the auto
mobile engineers attack the noise prob
lem. and the comparatively noiseless car
OF today Is the result. Here Is a great
demonstration: machine notoriously
noisy In its early designs is now reason
ably unobjectionable in this respect
Designing machines for safety is now
a we'll recognized principle in our draw
ing rooms. Designing machines for noise
less operation should be another aim and
one quite as worthy. The underlying
principle to follow is not difficult to dis
cover. Noise comes from vibration To
eliminate noise. eliminate vibration. But
not always as easy to discover the cause
of vibration as to note its existence
Perhaps the worst sinner, the most
noisy member of all machine parts, Is
the gear. The sounds it makes are
variously described as a rumble roar
squeal scream. shrek. and so on through
the list Of objectionable sounds. TO pro-
duce quiet-running gearing has been one
Of the great problems confronting the
automobile engineer in his efforts to at
tain nOiselesSness.
"The noise from gears is caused by
tooth striking its mate as 1t comes into
contact The struck tooth vibrates The
cause of the striking may be any one of
several causes. The most common is in
accurately formed teeth In general
there is more noise from inaccurate teeth
than from teeth too tightly meshed. In
the latter case the gears may roar, but
they do not shrek.
Under the same conditions we may
expect a web gear to be less noisy than
spoked one. In general, large teeth
run quieter than small teeth for the same
degree of accuracy in cutting. Wear may
reduce noise somewhat by rubbing off the
rough spots on the working curves, but
wear does not correct inaccuracies This
but shows that minimizing industrial
noise Is an engineering problem"
In an article in Casters Magazine on
this same topic of noisy machinery an
other writer tells us that noisy things are
worse than merely annoying-they are
inefficient. He says:
"One OF the surest indications Of per-
lection OF action in any piece of ma
chinery appears in nOiselessness of oper-
alton. We know that the humping and
pounding steam-engine Is less efficient
than one which is running smoothly and
silently. and 1t is apparent to the casual
observer that the noisy machine Is
wasting all the power required to create
the disturbing sound-waves. In the great
hydraulic power plant the real, efficient
work Is not performed by the noisy tor
rent which is splashing over the spill
way; 1t is stored in the great silent mass
held back behind the DAM while the use
full power is effectively generated by the
quiet column Of water descending through
the penstock and imparting its energy
to the turbine with the least practical
waste in noise-making
THE same considerations obtain in
other departments of work, and the ex-
perienced engineer knows very we'll that
any installment of machinery which is
creating q great hubbub and making
more noise than the results warrant is
would be the case If less noise were pro-
duced and more of the energy were de-
voted to useful effect.
IAN excellent example appears in the
case OF locomotive starting q heavy
train upon slippery rails. When the en-
gine Is first started there is a great noise
Of putting exhaust steam. the driving
wheels slipping upon the frosty tracks,
and little or no effort being expended in
begin to bite upon the sanded track and
| the train begins to move the barking
noise subsidies, and the effort OF the
steam in the cylinders, being expended