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Figure 11-14.—Front axle engagement air control diagram–legend. | Up
Construction Mechanic Advanced - Construction methods and practices | Next
Troubleshooting the Differential |
TROUBLESHOOTING THE POWER
TAKEOFF
Power takeoffs are attachments in the power train
for power to drive auxiliary accessories. They are
attached to the transmission, auxiliary transmission, or
transfer case. A common type of power takeoff is the
single-gear, single-speed type. This unit is bolted to art
opening provided in the side of the transmission case,
as shown in figure 11-15. The sliding gear of the power
takeoff will then mesh with the transmission
countershaft gear. The operator can move a shifter shaft
control lever to slide the gear in and out of mesh with
the countershaft gear. The spring-loaded ball holds the
shifter shaft in position.
On some vehicles, you will find power takeoff units
with gear arrangements that will give two speeds
forward and one in reverse. Several forward speeds and
reverse gear arrangements are usually provided in
power takeoff units that operate winches and hoists.
Their operation is about the same as the single-speed
units.
The troubleshooting and repair procedures for the
power takeoff are similar to those for the transfer case
and are listed in table 11-3.
TROUBLESHOOTING THE
PROPELLER SHAFT ASSEMBLY
The propeller shaft, or drive shaft, assembly
consists of the shaft, a splined slip joint, and one or more
universal joints. This assembly provides a flexible
connection through which power is transmitted from the
transmission to the differential. The propeller shaft is
almost always tubular.
A splined slip joint is provided at one end of the
propeller shaft to take care of end play. The driving axle,
being attached to the springs, is free to move up and
down while the transmission is attached to the frame and
cannot move. Any upward or downward movement of
the axle, as the springs are flexed, shortens or lengthens
the distance between the axle assembly and the
transmission. To compensate for this changing distance,
the slip joint is provided at one end of the propeller shaft.
The usual type of splined slip joint consists of a
splined stub shaft welded to the propeller shaft that fits
into a splined sleeve. A cross-sectional view of the
splined slip joint and universal joint is shown in figure
11-16.
A universal joint is a connection between two shafts
that permits one to drive the other at an angle. Passenger
Figure 11-15.—Power takeoff mounted on a vehicle transmission.
11-14
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