The Washington herald., 1917-11-25

ployed In them to transmit the power.
In the live axless OF today the COM
ponents are q hollow spheroid In the
center, from which project two tubes.
In the central portion Is the diner
ential unit, consisting of a number of
gears. Extending from the differen-
tial are two shafts. one through each
Of the tubes. To the ends of thes,
shafts the wheels are attached.
The names floating, semi-fioating
and three-quarter floating, are de-
rived from the shafts. The floating
shaft does In a manner do just that;
Il Is not required to support any OF
the weight of the load, but simply
drives the wheels and takes a little
torsional stress. In the floating axle
the wheel bearings are outside of the
axle tube, SO that the wheels really
rest on the tubes. In this way the
shafts may be removed without dis
turbing other parts.
In the semi-fioating type the outer
tube bearings are inside the tube and
the shafts must bear some Of the ac-
tual load, as well as absorb certain
torsional stresses. Obviously in this
design 1t Is not SO easy to remove the
type of construction the outer tube
bearings are on the outside OF the
tubes and there Is a regid connection
between the shaft and the wheel. This
axle, too. must support some Of the
load, in addition TO transmitting
power.
The gear types used in rear axIes
Of today include straight and spiral
bevel. worm. internal gear. two speed
bevel and single and double chain. OF
these types but three. straight, spiral
and two speed bevel. are used on
present day passenger cars. The spiral
bevel within the past few years has
come to the front and is now in the
lead in popularity. due to its quiet
running and general efficiency. The
two speed type is used by only one
maker.
No car owner who has experienced
rear axle trouble needs to be warned
to take all possible precautions TO
avoid 1t. Many serious troubles may
develop in this unit. IL IL is not treat
ed with due respect. Axle shafts
sometimes break. or again they may
be twisted out Of all reasonable shape
Bearings occasionally are crushed.
The gears in the dlfferential unit are
peculiarly liable to chipping, a trouble
that may result in running the whole
mechanism
The most Important item in the care
of the rear axle Is proper fabrication.
At intervals at least twice per sea
son. the rear axle housing should be
flushed out with kerosene and then
new oil should be installed. Note that
II be oil and not grease, which is un-
suited to this part, especially so in
cold weather.
But fabrication is not all. The func-
ton of the rear axle. as we have
noted. Involves the taking of torque or
twist, which puts a heavy strain on
the parts. II they are not strong
enough, trouble is bound to result.
When a part OF the rear axle assem-
bly, breaks. it should first be ascer-
tanned what caused the break. Often
the parts get out Of alignment and ir
this case, replacement will not help
for the unit must be Strengthened up
or the same thing will occur again.
Aligning the rear axle Is n job for the
service station. unless the owner is
unusually expert as a mechanic When
an intermittent hum, q noise with
stresses or infleXions, comes from the
axle, II may be accepted that the gears
are running out of alignment or that
they have suffered injury and are
themselves warped out OF shape. Chip
ping of the teeth is common and in
this case. the pieces of metal get
down in the mechanism and do fur
ther injury.
In placing lubricant in the rear