Hi again, esteemed list members. I was getting ready to make another
McMaster-Carr order, and I figured I should finally get around to
gathering up the hardware necessary to make the brake vent line
modification described in PS Magazine issue 364 (I have a copy of that
article on my web page). My truck is an M109A3 shop van, which is a
member of the M44A2 series, just like the well-known M35A2 deuce. The
parts list in the article lists the items by NSN, and I was able to
trick specifications for most of the parts out of the DRMS web site,
so that I'd know what parts to order.
One item eluded me: Item #4, NSN 4820-00-726-4719, referred to as a
"breather". It's the piece that goes on the end of the new vent tube
that is installed in the modification.
Please pardon my ignorance, but what, exactly, is a breather? Is it a
check valve, or a filter to keep out dust, or something else?
If I knew the function of the original part, I'm sure I could easily
find a suitable replacement. I'd hazard a guess that it's simply a
filter to keep out dust... probably similar to the little sintered
bronze filter I'm ordering anyway to cover the open exhaust hole in
the bottom of my 5-ton wrecker's pneumatic clutch control valve (the
one at the rear, along with the crane and rear winch gear shift
levers), just because I figured it would be a Good Idea. I became
aware of that exhaust port on Saturday, when I was working on my
wrecker. I started the beast up, and found that I wasn't building any
air pressure. I walked around and couldn't hear the leak, but I
noticed a short, soft breath of escaping air from the rear of the
truck when I stopped the engine. After more head-scratching and poking
around, I found out that air was escaping from that exhaust port
unless I disengaged the clutch lever. Hmm, it was working a week
ago... I finally figured out that there was probably a portion of the
valve that was sticking open, that would normally be forced back into
place by the supply side air pressure. I had fiddled with the lever
with the engine off while showing off the truck earlier in the week,
and that probably stuck the valve open. Fixing the problem was a
simple matter of disengaging the clutch control handle until the
system built enough air to reset the valve, and then remembering not
to monkey with it without air pressure in the future! That exposed
exhaust port (which has probably been open to the atmosphere since
1965) bothered me, and I decided it was time to install a $2 exhaust
filter in it. :-)
Meanwhile, back at the ranch, once I get around to performing the
brake vent line modification (maybe next month, maybe 15 years from
now...), I may update my web page to include descriptions of the items
in the parts list, most of which would probably be available at the
local hardware store if only you knew what the NSNs meant.
Thanks in advance for any advice!
Boy, I sure know how to make a short story long... :-)
-- Mark J. Blair, KE6MYK <mblair1@home.net> PGP 2.6.2 public key available from http://www.keyserver.net/ Web page: http://www.qsl.net/ke6myk/ DO NOT SEND ANY UNSOLICITED COMMERCIAL EMAIL TO THIS SITE PLEASE SEND PLAIN ASCII TEXT ONLY -- NO HTML OR QUOTED-PRINTABLE
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