(a) Support boom hoist drum (461
inner races of bearings (20 and 19) and install the inner
races on each end of the shaft. The races must be
with suitable sling and slide it off shaft (10, ) as
pressed firmly into place in one motion and must bear
assembly. Items (1) through (14) and (45, 47, 48 will
against spacers (32 and 39) to form one solid assembly.
come off the shaft with the drum.
(b) From the opposite end of the
(6) Install the subassembled shaft in the
bore in the revolving frame and block it firmly in position
boom hoist shaft, remove lockwire (23), two capscrews
with the shaft centered in the bore. Worm wheel (40)
(24), keeper plate (25), and sprocket (26). Remove O -
must be engaged in the worm shaft.
ring (27) and spacer (28).
(7) Install the outer races of bearing (20
(c) Place suitable blocking beneath
and 19) in bearing retainers (21 and 18). Install bearing
each end of the shaft to prevent the shaft from dropping
retainers on shaft (10) and secure in position with eight
when bearing retainers (29) and (43) are removed.
Remove bearing retainers (29 and 43) by removing six
(8) Subassemble oil seals (22 and 44) into
retainer. Oil seals (22 and 44) will come out in the
retainers (29 and 43). Be sure the seals are installed
with the springs facing sprockets (33 and 381 and that
Remove eight nuts and
the areas between the seal lips are packed with GAA
lubricant. Check seal seating surfaces of the shaft for
18). Remove bearing retainers (21 and 18). Two tapped
nicks or burrs; minor imperfections on the shaft can
pull holes are provided in the bearing retainers to assist
cause rapid seal wear.
(9) Install shims (40, 41, and 42) in equal
amounts between bearing retainers (29 and 43) and
(20 and (19) from the shaft, using a suitable puller.
retainers (21 and 18) so that shaft end play is between
(f) Remove sufficient blocking from
0.003 and 0.005 inch, using a dial indicator. Install the
each end of the shaft to disengage the worm wheel (35)
two bearing retainers (29 and 43) using six capscrews
from the worm shaft. All remaining items on shaft (32
and lockwashers (30 and 31).
through 39) can then be removed by removing the shaft
Adjust worm wheel-worm shaft
through the right side of the chain case. Strip items (32
backlash as follows.
through 39) off shaft (10). Do not disassemble worm
(a) Turn the worm shaft through one
wheel assembly (35).
Check the points of contact
Note. Always replace both drive chains if
between the worm and worm wheel (35) shown on the
one must replaced.
no load conditions, all contact must be to the left of the
worm shaft if it has been removed. The worm shaft must
center of the worm shaft. Note that the tooth contact
be installed before the boom hoist shaft can installed.
must be checked by removing the inspection plate
(2) Install key (36, FIG. 2-11) and press
shown in figure 2-10 and that it must be inspected at the
worm sheet assembly (35) on shaft (10). The faces of
bottom of the worm wheel, since the top cannot be seen.
wheel assembly (35) hub must be flush with the shaft
(c) If all contact is not on the left side
(10) shoulder, as illustrated.
of the worm shaft, move shims (40, 41, and 42) as
(3) Coat worm wheel teeth (35) with a light
required to a point beneath the opposite bearing retainer,
coating of white lead of Prussian blue. This will used
until proper contact is established. Recheck boom hoist
later to adjust the worm wheel-to-worm she gear contact.
shaft end play.
The finished face of the worm which must be placed on
(d) Use a suitable sealing compound,
the right side, as viewed from the rear, of the shaft.
such as Permatex NO. 2 on capscrews and lockwashers
Install spacers (34 and 37) and
(30 and 31) and adjacent sealing surfaces.
sprocket (33 and 38). The sprockets must be tight again
(11) Subassemble the boom hoist drum
(46) as follows.
Note. Sprockets (33 and 381 are match
Position drum (46) on the
marked during manufacture and must be installed in
workbench with the ratchet side up. Pack drum with
matched pairs. Be sure both sprockets have the same
grease, type GAA, as described in the current LO.
number stamped on the outer face. See that the match
(b) Tap bearing (45) into the drum
marked internal spline on each sprocket mates properly
until it is firmly seated against the drum shoulder. Turn
with the marked splines on the shaft.
drum over and finish packing drum cavity with grease.
(5) Install spacers (32 and 39). Warm the
Install bearing (47) in this end of drum. Place spacer
(15) on top of bearing (47) as shown.