PS Magazine - TB 43-PS-561
PS, The Preventative Maintenance Monthly
ISSUE 561
AUGUST 1999
PS 561
5
AUG 99
here have been two manufacturers of the air brake governor assembly, NSN
2530-00-854-4457, used on M939-series and M939A1-series trucks.
One assembly, FL Industries’ part number N-20856-D, is no longer available.
The other assembly, Allied Signal’s part number 7003-03C068537, is avail-
able—and interchangeable—
as an assembly
, but not in parts.
If you have problems interchanging these governor assemblies, ask your sup-
port unit to add a tee, NSN 4730-00-782-5461, to the hookup. It’s Item 15 in Fig
150, TM 9-2320-272-34P-1.
Details on how to install the tee are found on Pages 3-580 through 3-583 of
TM 9-2320-272-24-1.
Do not try to mount either of these assemblies on M939A2-series trucks. They
do not have the low-pressure cutoff for CTIS that reserves air pressure for
braking in case of air system failure. You must use assembly, NSN 2530-01-287-
4529 (PN 106400), for A2-series vehicles.
To ensure that you get the correct assembly when ordering, add the part
number to your requisition’s Remarks block.
M939-Series Trucks . . .
Following the Trailer
Get the knack of following the trailer. You’ll need this skill when
you’re backing into a parking space. When you start the turn, your
truck’s going one way and your trailer’s going the other. As you get
well into the turn, start turning the steering wheel back in the opposite
direction to bring the truck and trailer into line.
Take it easy, though. If you turn the steering
wheel too far, your trailer will turn in the
opposite direction. Try backing this way:
With practice,
you’ll be able to
back your combo
around a corner
and then follow
the trailer in a
straight line.
When you’re
backing into a turn,
make it toward your
left side when possible. There’s less chance of clobbering something behind you.
And make it easier on the next driver if you’re among several parking in a line.
Park so others can back alongside on their “good” left side, saving damage to
both your vehicles.
1
2
3
1.
Turn your front
wheels to the right
to start your trailer
backing to the left.
2.
As your trailer begins to turn, start turning
your front wheels to the left to follow the trailer.
3.
Start straightening your front
wheels before you finish the turn.
You’ll end up with your truck and
trailer traveling in a straight line.
now
there's
a man who has
put in his
parking
practice
.
what
are
you
?
i'm the
air
brake governor
that
fits
to
a
tee
!
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