PS Magazine - TB 43-PS-637

PS, The Preventative Maintenance Monthly

ISSUE 637

DECEMBER 2005
PS Magazine - TB 43-PS-637 - Page 4 of 33
Dear CW3 J.H.,
From what you’ve said, it sounds like you may
need to adjust the cam bracket operation cable.
If the cable is too far out of adjustment, the crank
boss misses engagement with the cam bracket dur-
ing the counter-recoil stroke. That’s what mechani-
cally cycles the breech open so the extractors can
expel the aft cap.
The adjustment procedures for the cam bracket
operation cable start on Page 8-70 of TM 9-2350-
264-20-2-4 (Apr 03), Page 8-55 of TM 9-2350-288-
20-2-4 (Aug 95), and Page 8-61 of TM 9-2350-388-
20-2-4 (Feb 01).
M2/M3, M2A2/M3A2 Bradleys, MLRS Carrier…
M
echanics, when you’re working on the Bradley or MLRS’ 300-amp
generator, NSN 6115-01-458-0096, have some mercy on the output stud nut.
There should be a decal beside the
stud nut that lists the proper torque
requirement of 16 lb-ft. When some
generators were rebuilt, however, the
decal was removed.
As a result, some mechanics don’t
tighten the stud nut enough while
others tighten it too much. Too loose
and the nut will vibrate free. Too tight
and the insulator may be damaged.
And no LocTite, either. That affects the torque value and can cause damage.
PS 637
DEC 05
4
M1-Series Tanks…
If the ejection problem still exists after you adjust the cable,
take a look at the extractors themselves. There is a small lip
machined on the upper inside edge of each extractor. These
lips are what grab the aft cap and extract it. If they wear down
or break, they won’t grab like they should.
I’d also suggest that you manually exercise the mount. Use
the M-3 oil pump and get the mount out far enough that the
lobe on the crank extends past the cam (about 10 inches). With
the manual handle in the armed (down) position, you should
be able to see the cam snap into position. Then you can let the
mount back into battery and watch the breech operation.
Cam bracket operation cable out of adjustment?
Decal gives torque value for output stud nut
looks like
you’ve still
got that
flashback
problem!
maybe
master
sergeant
half-mast
can help!
the
mechanic
didn’t
torque
my gen-
erator’s
output
stud nut
to
16 lb-ft!
Dear Half-Mast,
We’re currently
going through gunnery
and have had some
problems with one of
our M1A1 tanks.
When the tank fires,
the breechblock
doesn’t drop to allow
the aft cap to be
ejected from the
chamber. Since we
have to manually
extract the aft cap,
there’s the additional
worry about unburnt
propellant and gasses
causing flashback in
the turret.
We’ve cleaned and
lubed the breech well.
The tank seems to fire
and recoil with no
problems. Any idea
what could be causing
the situation?
CW3 J.H.
thanks for
writing, sir!
that
rattling is
driving me
crazy!
what is it?
CAUTION TORQUE STUD
22 Nm/16 LB-FT
637.04-05(C!).qxd
11/3/05
5:28 PM
Page 1
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