Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1917-08-05
.!s|MPL|F|ED LESSONS ON
CARE OF AUTOMOBILES
Intimate Talk on Working Units
Which Laymnn Can Easily
Understand.
ABOUT THE PROPELLER SHAFT
Usually Solid Piecc Of Steel Which
Requires No Attention-Connect
cd to Power Plant by Means Of
Universal Joint.
LESSON NO. so.
Propeller Shaft.


copyrighted. 1917. by F. C.. Guerrlich.)
AS tho engine is placed in the for
ward part OF tho car. whilo the wheels
which arc to BIO driven by, the engine
are placed somo feet in tho rear Of
the engine. the two must be connected
by shaft. This shaft is called the
propeller shaft" Sometimes Il is call
ed the driving shaft but this name
Is generally given TO tho driving shofts
In the rear axle.
The propeller shaft IL usually moth
ing more than a piece OF solid round
steel. though for lightness sake, 1t
is often a tube Of steel It itself re-
quires no attention and practically
never gives trouble.
The propeller shaft is connected to
the power plant, and in most cars to
the rear axle. by what Is known Jas
the universal joint" which might be
DENIED as device for Transmitting
revolving motion from ono shaft TO an
other. when the axes OF these shafts
are at an anglo to ono another.
AS tho universal is O hard-to-get-
at part Of the car, It's fabrication is
seldom properly looked after, so man.
ufaeturers have finally designed a Joint
which can be packed with enough
grease to last for many thousand miles.
and which Is as nearly neglect proof
as possible.
Why do we need the universal Joint?
The rear axle is attached to tho
frame by means Of springs, and 80 the
height OF the frame above tho axle is
constantly changing. and therefore the
angle OF the propeller shaft to the
crank shaft OF the engine will con.
stantly be changing. This makes 1t
impossible to have these two shafts
In a straight line at all times. and
therefore the universal. which will
drive through the varying angles. must
DC used. In most cars, the propeller
shaft will be in line with the engine
SHAFT when the car is fully loaded,
but must, because OF the spring nc
ton, then be at an angle when OILY
partially loaded
Let us see how the universal Joint
Is designed. Let a Gig. y be one
shaft, and the other at an angle
thereto. Let US next fastcn to a
fork. like arm C. and TO B another, az
d. II we could now couple these two
iorks together in some way SO that the
smart Il could move UP and down, with
The FORK d as pivot. and A sIdewa ys.
win the fork G rs pivot. our prob.
lem would be solved. This can he done
by coupling them with a spidor. az
shown In Fig. T. In Figs. . and q, the
coupled universal joint is shown
BY observing Fig. 2. you will notice
that tho spider is in a horizontal
position. and that the fork and shaft
u have swiveled on it's pins. AS the
smart makes quarter OF a revolution
the universal will take the position
shown In Fig. g. Here you Will no.
tice that the spider has swiveled on
the fork c and is now ut an nnrle
to the horizontal. When the shafts
have made but an eighth OF a revo-
luton. the propeller shaft will have
partly swiveled on the spider. and The
spider will have partly swiveled or the
fork of the driving shaft Thus YOU
see that by means of this double swivel
the shaft will be driven even when M
on angle.
1t Is found that for one-quarter OF
revolution. the driven shaft will be
slightly retarded. while for tho NEXT
quarter. 1t Will be slightly acceIer-
ated. then 1t will again be retarded ma
again accelerated. 30 that the drive
OF the rear wheels will not be absolute
~ uniform. To overcome this dificultv
Two unlversals are generally used.
the forks on each end of the propeIler
smart being placed at right angles to
one another. In this way the retard.
Ing action OF the one will come during
the accelerated action Of the other. thus
equalizing the fault and giving a uni
form drive.
Were the propeller shaft positive
~ connected to the universal Joint,
then the rear axle, as 1t moves up and
down with respect to the frame. would
have to move through an arc Of a
circle. the center OF which is the front
universal. In many cars the spring.
torque arm or radius rods are SO de.
signed that they will not permit thi,
The propeller shaft 10 therefore con-
nected to one Of the universals in such
manner as to be able to slide back
and forth In 1t. which is usually done
by having its end square. and fttine
1t into square hole in one Of the mi