PS Magazine - TB 43-PS-588
PS, The Preventative Maintenance Monthly
ISSUE 588
NOVEMBER 2001
M109A6
Paladin…
PS 588
NOV 01
20
M109A2-A5 SP Howitzers, M992A2 Ammo Carriers…
A
bad rectifier ground causes a
whole slew of problems for
M109A2-A5 howitzers and the
M992A2 ammo carrier. Low volt-
age readings and burned-out voltage
regulators are pretty common.
If you see any of these problems,
mechanics, re-ground the rectifier like this:
1.
Remove the rectifier from the hull wall.
2.
Clean the corrosion, paint and sealing
compound from the mounting base, the
mounting base bolt holes, and the hull mat-
ing surface with clean rags and crocus
cloth, NSN 5350-00-221-0872.
Take special care to clean the threads on
the two brass bolts, too. They are the real
grounding points for the rectifier.
3.
Apply a fresh coat of silicone compound,
NSN 6850-01-137-8525, to the bottom of
the mounting base and the mating surface
of the hull.
4.
Reinstall the rectifier. Make sure you use
new lock washers on the mounting bolts. If
you don’t, the bolts come loose and the rec-
tifier loses its ground.
Get new lock washers with NSN 5310- 01-334-4710 for the M109A2-A5 and
NSN 5310-00-913-9776 for the M992A2.
Remember,
only the two brass bolts take lock washers on the M109A2-A3 rec-
tifier. It’s OK to reuse the flat washers that come with the remaining four bolts.
holy cow!
a burned out
voltage regulator
and
overcharged
batteries!
sounds
like the
rectifier’s
not
grounded
properly!
Bad rectifier ground
causes problems
Rectifying a Bad Ground
W
hen it’s time to move the Paladin’s gun
tube travel lock to the maintenance position,
do it right or you and the travel lock could
need maintenance—maybe even replace-
ment!
The travel lock weighs almost 500 pounds,
so never let it drop against the bracket rests
after removing the quick-release pins. The
bracket rests are designed to hold the travel
lock in the maintenance position, but only if
the lock is lowered gently. If it’s dropped, the
bracket rests could shear off.
When that happens, the travel lock falls
forward until its bottom hits the hull. The
lock is damaged—and so are you if you hap-
pen to be in the way!
Protect yourself and your Paladin. Lower
the travel lock slowly to the maintenance
position.
Don’t Drop the Travel Lock!
Brackets snap
off when
travel lock is
dropped
Never
stand behind the
breech block while your
Paladin’s cannon tube is
being exercised.
If there’s
any damage
to the recuperator, the
cannon tube can fall out
of battery when it reaches
maximum elevation.
Anyone standing
in the way will be
squashed flat.
Don’t be a victim! Stand
away from the breech
block any time the cannon
tube is raised or lowered.
588. 20-21 (C)
9/29/01
4:52 PM
Page 1
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