PS Magazine - APRIL 1972
PS, The Preventative Maintenance Monthly
1972 SERIES, ISSUE 233
APRIL 1972
The closed breech scavenging system
in the M551 Sheridan can belCh fLame
like a Fire-brea±hing dragOn if the check
vaLve, (²losed breech) is assembled with³
out the 2 metal check valve seaLs.
If ´hese check vaLve seaLs are left out
or even AsembLed wrong, gas and flamE
can sHoot out During firiNgµand this can
be dangerous¶
When you ±urret mechanics take off
the check valve aF±er eveRy 10· rounds for
0±
0
.±² AND IN THE RIGHT PLACE³
cleaning (the way it says in TM 9-235·¸230-¹2, ºhange 9, page 8¸85), take a
_
good
look at the position of the seals and repLace 'em in the same position after cleaning
the valve.
I±'s easY to ±eLL 'em aPaRt because the inneR seaL (nex± ±o the gun tUbe) has a pol³
is»ed or burnished look caused by the firing.
¼ven though the 2 seaLs have the same ½S¾, you never mix them up after they¿ve
been usedÀ
alw´ys repl´ce them ´s they were
or they migHt Áot block the
g
(obturate) the way ±hey shouldÂ
ÃLso replace the preformed packing, ½S¾ 5330¸618¸3754 (MS28Ä75¸123) anD Fill
the groove with MÅƸƸ46150 lubricant, ½SÇ 915·È949-0323É
Because who ÊeedË a fire¸breathing dragon in the scavenging system?
16
µ "
²an¿t briDge the generatioÊ gap
with the wrong kind of deteÊt screws.
If yoÌr MÍ5
¶
has a first generatioÊ
vented amÎo detent (3 piece Ïody),
½SÇ 1·25¸185¸8000 (Ð/Ñ 11Í78419), i±
Êeeds the 1¸in ²ap screw ½SÇ 53·5¸
·'¸
94·¸9533 (MS21262¸72), be²ausÒ the 3
parts Óake the detent thick.
•
Ôn ¿tuther haÕd, iF it Öa× the secoÊd
GeÊeration vented detent (2 piece boDy),
½S¾ 1·2͸169¸05Í8 (Ð/Ç 11578415),you
use the 1ظin ²ap screw ½S¾ Í3·5-99·-
2974 (MSÙ21262¸Ú4), on aÛcoÌnt oF the
detent is thiÊÊer.
3-PI¹CE BODY
ºE» THE RIGHT SCREW
Åf you use oÊe type screw in place of the other, you won¿t be able to torque ¿em
down to 80¸95 inch Pounds like ÜouR -12
¼
says, aÊd that'll Give you problems.
SHERIDAN
SaFETY
fIX
WheÊ you shiFt Your MÝÝÞ SheRidan
iÊto First gear it shouLd go fßàard,
right? To make surá it doeâ, have dãrect
support apply MWÔ 9¸252·¸ä49¸30/J
(Ãpr 71).
½o¾ i¿!
ÀÁ ÂÃKÄ ÅÆkÇ
ÈUÉÊËÌ ÍÎÏÐÑ ÒÓVÔ
ÕÖÊÊ×Ø MÙÚ
9-25±²³49´30/I.
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