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Figure 11B-165. Fixture for Testing Bearing Pre-Load
CRANKSHAFT TIMING GEAR

Maintenance Manual For 40 Ton Crane Crawler Mounted Page Navigation
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NOTE
B. Attach the third plate to the idler
gear hub with three 3/8"-16 bolts.
N e w locking bolts should always be
Tighten the bolts to 25-40 lb-ft (34-54
used when attaching the bearing
Nm) torque.
retainer to the idler gear.
C. Clamp the idler gear assembly and
fixture in a vise (see Figure 11B-167)
2.
Bend
the
ears
of
each
bolt
lock
against the flat side of the attaching bolt
D. Attach the cord to the idler gear and
h e a d s to secure the bolts.
spring  scale and check the pre-load
as previously described.
Install Idler Gear Assembly
If the scale reading is within the speci-
f i e d 1 / 2 t o 4 I b s . ,  but fluctuates more
1. Position the crankshaft gear and ei-
than the permissible 2 Ibs. 11 ounces,
ther the balance shaft or camshaft gear
the idler gear and bearing assembly must
(depending upon engine rotation) so that
Fluctu-
not be installed on the engine.
the timing marks will align with those on
ations in scale reading may be caused by
t h e i d l e r g e a r  (see Figure 11B-144 on
the cones or races not being concentric
page 11B-93).
to each other, damaged cones or races or
rollers,  or dirt or foreign material within
2. With these marks in alignment, start
In these cases, the bear-
the bearings.
the idler gear into mesh with the crank-
ing should be inspected for the cause of
shaft gear and the camshaft gear, and
fluctuation in the scale readings and cor-
simultaneously  r o t a t e t h e g e a r h u b s o
rected or a new bearing installed.
that the hollow dowel at the inner face of
the hub registers with the oil hole in the
A scale reading which exceeds the speci-
end plate.
fied maximum indicates binding of the
bearing rollers, or rollers improperly in-
3. Roll the idler gear into position, align
stalled.
When the scale reading is less
the hollow dowel with the hole in the end
than the specified minimum, the bearing
plate,  a n d g e n t l y t a p t h e h u b u n t i l i t
is more likely worn and should be re-
Thus the
seals against the end plate.
placed.
hollow dowel in the hub will conduct oil
through the end plate and into the hub
After the pre-load test is completed, re-
where it flows through a drilled passage
move the steel plates and install the
to the roller bearing.
bearing retainer as follows:
4. After making  sure that the hub is
1. Attach the bearing retainer to the
tight against the end plate, secure the
idler gear with six bolts and three bolt
idler gear assembly with a 1/2"-13 bolt
Tighten the bolts to 24-29 lb-ft
locks.
and special washer.  Tighten the bolt to
(33-39 Nm) torque.
80-90 lb-ft (108-122 Nm) torque.
install
5. If previously removed,
the
idler gear hole spacer (dummy hub).
Secure the spacer to the cylinder block
end plate  and cylinder  block with a
1/2"-13 bolt and special washer. Tight-
en the bolt to 80-90 lb-ft (108-122 Nm)
torque.
6. Lubricate the idler gear and bearing
liberally with clean engine oil.
7. Check the backlash between the mat-
i n g g e a r s .  The backlash must be 0.002"
to 0.008"  between new gears and must
n o t exceed 0.010" between used gears.
8. Install the flywheel housing.
Figure 11B-167. Check Pre-Load of
Idler Gear Bearing
11B-110


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