STRUCTURAL CD3340B/YB4411
11-56
Published 04/07/2015 Control # 569-00
Mast Bearing
The mast bearing is a ball thrust bearing. The inner race
rotates inside the outer race on a row of steel balls.
Apply grease after every 50 hours of operation. Use a
Lithium based, E.P. No. 2 bearing grease or equivalent.
There are two grease fittings to grease the bearing and they
are directly across from each other. Rotate the mast until the
access hole (Figure 11-139) aligns with the grease fitting.
Apply grease to the bearing. Rotate the mast through several
rotations and then repeat the procedure with the other
grease fitting. The old grease will be removed at the bottom
of the bearing.
Mast Bearing Bolts
Very high stress is put on the mast bolts during crane
operation. It is important that these bolts be checked at
regular intervals.
Check the torque on the bolts after the first 50 hours of
operation, and then after every 250 hours of operation. Make
a record of any loose bolt. If any bolt does not hold to correct
torque after the second check, remove and replace the bolt.
A loose bolt indicates possible failure of the bolt.
The correct torque on each outside bolt (mast to swing
bearing) should be 245 Nm (180 lb-ft). The correct torque on
each inside bolt (swing bearing to frame) should be 384 Nm
(282 lb-ft).
Use the torque sequence shown in Figure 11-140 when
checking the torque on the bolts.
NOTE: Use only special hardened bolts for replacement of
the mast bolts. Order the bolts from your distributor,
see your parts manual.
NOTE: If a broken bolt is found, replace the bolt and also
replace the bolt on each side of the broken bolt.
FIGURE 11-139
P0325
Access Hole
Reference Only
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