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Bulletin: SVB-113
Date Issued: June 27, 2005
Category: Design Improvement
Subject: Block Pusher Assembly modification to prevent falling
Machine Models: Jumbo Top Feeders, Jumbo Bottom Feeders, Block
Push Bottom Feeders, Top Feeders
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Problem:
An operator of a
recently delivered Jumbo Top feeder (JTF) reported that the block
pusher assembly had fallen off its drive tracks multiple times
during the initial few months of service following installation.
Inspection
revealed that the block pusher assembly shaft support bearing on
the drive side had moved slightly upwards, allowing the pinion gear
on the drive shaft to become disengaged from it’s mating stationary
rack gear. This hardware is illustrated below. This driveshaft
support bearing has a secondary jackbolt installed to prevent
movement of the supporting bearing, however, the jackbolt had become
damaged and allowed some bearing movement to occur due to the loads
from the block pusher drive motor into the drive shaft.
In response to
this report, Alliance has redesigned the jackbolt and jackbolt
mounting tab to provide stronger parts and better contact with the
bearing housing. This design change became effective in June 2005
for all Alliance prefeeders.
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Recommended
action:
Alliance
recommends that you perform an initial inspection as described below
within 90 days after receipt of this service bulletin.
If the initial inspection is satisfactory Alliance recommends that
you perform a repeat inspection at annual intervals.
However, if the attached modification is accomplished further
repeat inspections are not required.
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Procedure:
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De-energize the prefeeder and
install lock-outs per the Operator Manual.
-
Using a ladder, remove the sheet
metal guard at the upstream end of the block pusher assembly
that guards the gears. On both operator and drive sides
visually inspect the –
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block
pusher assembly driveshaft pinion gears for any signs of
looseness with respect to the rack gear
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driveshaft support bearing for any signs of movement or
loose bolts
-
jackbolt
and jackbolt mounting for any signs of bending, damage, or
distress
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If any of
the conditions above are found, Alliance recommends you perform
the modification per the attached drawing 1032211 on both sides
of the block pusher assembly. We estimate the modification
requires 2 man-hours per side to accomplish.
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Remove
lockouts and re-energize the prefeeder. Manually operate the
blockpusher assembly forward & reverse several times to check
for proper block pusher operation.
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