PROPELLER SHAFT
TRUCK SERVICE MANUAL
General
shaft speeds. Where the flange also maintains the
stance, if the transmission mainshaft center line at the
rear is down 5 degrees from a true horizontal plane, the
shaft center bearings, this adjustment is destroyed
center line at the front of the auxiliary mainshaft or rear
because of lack of torque on the nut. When a
axle pinion shaft must be 5 degrees up.
companion flange is removed from a transmission,
center bearing or rear axle, the flange and shaft should
With the nonparallel or "broken back" type
be marked so that the flange can be reinstalled in the
installation the working angles of the joints ("A" and "B",
same position on the shaft. Be careful during the
Fig. 3) of a given shaft are equal; however, the
removal or replacement of companion flanges, as rough
companion flanges and/or yokes are not parallel.
handling such as hammering on the trunnion mounting
Example: The flange or yoke of the main transmission is
may bend or distort the flange.
3 degrees from a true vertical with the rear axle pinion
flange or yoke at 12 degrees. The working angles of the
Center Bearing: Tighten the propeller shaft center
universal joints of this propeller shaft are equal and the
bearing mounting bolts. Should the center bearing
shaft will run smoothly, Fig. 3.
insulator be deteriorated or oil soaked, it should be
replaced. Loose mounting bolts or an oil-soaked or
deteriorated insulator can cause excessive vibration.
See "PROPELLER SHAFT, " Section A, CTS-2046.
Engine and Transmission Mountings: Tighten the engine
and transmission mounting bolts. If the mountings are
oil soaked or deteriorated, they should be replaced.
Loose mounting bolts or oil-soaked or deteriorated
Fig. 3. "Broken Back" Type Drive Line
mountings can cause excessive vibration.
When the propeller shaft angle is determined in the
Clutch and Flywheel: The light side of the flywheel is
nonparallel type installation, the rear axle is rotated about
stamped with a letter "L" and should be lined up with the
the axle shaft axis until the pinion shaft and transmission
arrow or inspection mark (usually a white dab of paint)
mainshaft extended center lines intersect exactly midway
stamped on the heavy side of the clutch. (If no arrow is
between the universal joints centers ("'D" and "E", Fig.
stamped on the clutch, it can be assembled to the
3). It can be readily seen that the pinion and mainshaft
flywheel in any position. ) If these markings are not lined
center lines may be quite different with respect to a true
up, excessive vibration can result.
horizontal; however, the joint working angles ("A" and
"B", Fig. 3) are identical.
DRIVE LINE ARRANGEMENTS
UNIVERSAL JOINT WORKING ANGLES
There are two types of drive line arrangements that
will satisfactorily transmit power to the driving wheels:
The major prerequisite for obtaining troublefree and
the parallel joint type and the nonparallel or "broken
long-lasting operation of a drive line is consideration of
back" type.
the universal joint working angles.
Any given universal joint has a maximum angle at
which it will still transmit power smoothly. This angle
depends on the joint size and design. To exceed the
maximum recommended working angle is to greatly
shorten or immediately destroy the joint service life.
Fig. 2. Parallel Joint Type Drive Line
The universal joint working angles of both joints of a
In the parallel joint type all companion flanges and/or
given propeller shaft should operate at the same angle
yokes in the complete drive line are parallel to each other
with not more than one-half degree of variation.
with the working angles of the joints ("A" and "B", Fig. 2)
of a given shaft being equal and opposite. For in
If the working angles of a given propeller shaft are
not equal, joint cancellation will not occur, resulting in
destruction of the joint.
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