PS Magazine - TB 43-PS-687
PS, The Preventative Maintenance Monthly
ISSUE 687
FEBRUARY 2010
16
PS 687
But service brake adjustments for M101- and M116-series trailers are not so
simple. Some operators tried to make adjustments, overdid it, and made things worse!
Improper service brake adjustment can cause serious damage to the brake shoes,
brake drums, and other key components. So get your mechanic on the job to make the
necessary adjustments using TM 9-2330-202-14&P.
Never drive off with your trailer unless the service brake and parking brake work.
Test ‘em! After you hook up the trailer to the prime mover, apply the brakes and move
slightly to see if the service brakes hold the trailer wheels. And the parking brake
should keep the trailer from moving when it is not hooked up to the prime mover.
Properly
adjusted
brakes
should create a drag on the
forward movement of the prime
mover. The trailer wheels might
also rotate in a restricted manner.
If they do this, the brakes are
adjusted properly, so go ahead
and complete your mission.
If the brakes don’t hold—or
there’s no prime mover drag—ask
your mechanic to put the “brake”
back into your brakes.
The artwork for the Underlift
Assembly Operation in WP 0037
00-01 of TM 9-2320-392-10-1 (Mar
09) and IETM 9-2320-391-10-1/2
(Mar 09) is incorrect. The shutoff
valve is shown in the closed
position but the callout says the
valve is in the open position.
The written instructions for
this task correctly state that
the valve must be in the open
position. However, because the
artwork is wrong, some users
have mistakenly placed the valve
in the closed position, damaging
the boom winch.
FMTV…
TM
Art Can
Damage
Wrecker’s Boom Winch
most small trailer parking
brake adjustments are
simple.
all you have to do is turn
the adjustment knob on the
end of the handle clockwise
until the trailer wheels no
longer rotate freely when
the handbrake is applied.
by the way,
painting the
parking brake
handle can
freeze
the
knob that needs
to be turned.
the brake can’t
be adjusted if
that happens,
so make sure
you still have
motion after
painting.
and keep the cable
and hand assembly
lubricated like
appendix I in the
tm says.
Call mechanic if
brakes won’t hold
but there
are
exceptions.
your
m1089a1
fmtv’s
underlift
assembly
operation
in tm 9-
2320-392-
10-1 is an
example.
most of
the time,
your tm
does a
good job
of showing
you what
“right”
looks like.
this tm tells me to have this
hydraulic shutoff valve in the
open position, but the picture
doesn’t look right.
you’re
right!
here’s
the word.
{boo hoo
hoo}
it’s
not
my
fault!
687.16-17.indd
1-2
12/21/09
4:28:42 PM
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