El Paso herald. (El Paso, Tex.) 1901-1931, 1918-04-20

4 MONG the subsidiary mechanical
units Of the modern motor car,
which gives trouble only on occasion.
must be included the speedometer. IN
spite Of the delicate nature Of this IN
trument, 1t is not often that the mo-
-fst has occasion TO attempt repairs
I or IT, However. when such an occas-
ion does arise some knowledge Of the
device is essential.
At the present time there are IN
service four definite types Of speed
ometers-magnetic. centrifugal. by
draulic and that driven by air current
! The magnetic type Of speedometer is
Z probably the most popular type. as
far as the number Of makes Of cars on
which it finds a place. a typical con-
struction in this class employs but
one moving part, q circular magnet
Over this. magnet, but not touching Il.
IS an inverted metallic cuD. on the
rim OF which IS a row Of figures. in
/ ulcating the miles per hour The mag
net is revOlved by means Of q flexible
shaft, its field acting on the dial cuu.
As the speed OF the magnet increases.
so does the magnetic pull ana the
dial cup IS drawn around TO Indicate
the increasing speed. The dial IS
mounted on a steel shaft with q lew
eled bearing at the ton. A hairsDring
Is fitted 20 resist the pull OF the
maEhet and this also serves to return
the cup 10 zero when the car stops.
Tn general a temperature compenEaror
IS fitted in this type. to prevent the
1airsDring being affected by climatic
changes.
Within the past year or so the air
current type Of speedometer has been
achieving q considerable popularity.
mis- type OF instrument employs q
stream Of air 90 turn the dial which
indicates the mileage. a typical con
structiOn In this class has a flexible
smart driving an air circulator. con-
sisting OF two elongated aluminium
gears, placed In the head of the in
strument and opening into an air
chamber This latter has two open
ings. one an entrance for. the air. the
other an exit A dial fitted with q
Fale revolves the dial 10 show sppro-
1riate figures. A hairspring is used
70 return the dial 70 zero when the
car stops.
Centrifugal Typs.
The centrifugalIy operated speed
ometer. Is actuated on the same prin-
ciple found in the f1ybau governor.
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shaft by means Of levers or cranks.
so that the movement OF the weights
by centrifugal force is communicated
through the shaft 70 the dial. When
the car sDeed Increases. these weights
tend TO fly out and. being connected
with the dial through the shaft, pull
the former around to the right and
display the correct figures for The
miles per hour
The hydraulic type Of speedometer |
has not gained any considerable fol- I
lowing as yet, though its many excel [
lent Qualities may eventually win .
recognition
All speedometsrs have certain
characteristics in common; the varia- /
tons In type generally refer 20 the
means employed OF actuating the F.
mileage dial All these instruments Z
have a connection in the shape OF q /
rotating shaft that IS flexible and IS I
housed in q flexible housing, running ]
TO some running part OF the mechan- /
Ism. usually a front wheel On the
end OF this shaft IS a gear. which I
meshes with q gear on the moving !
part employed. This shaft is driven /
from the cars mechanism and in !
turn Il drives the mechanism OF the I
spsedOmeter through some SOFT o. q I
Joint II has fl the past been the I
Drac tically universal custom TO con
1ecr the sDeedometer with q 'front.' +