PS Magazine - TB 43-PS-617
PS, The Preventative Maintenance Monthly
ISSUE 617
APRIL 2004
PS 617
APR 04
10
HEMTT Tankers…
Replace
Old Gauges
O
perators, many M978 fuel tankers are
still equipped with old-style differential
fuel pressure gauges. They’re not as reli-
able as the newer, more durable gauges
that come with NSN 6685-01-362-4272.
The old gauges start at 5 psi; the new gauges
start at .5 psi. That lets you better keep up with the
amount of dirt in the fuel filters.
As the filters get dirty, the pressure differential should slowly increase. That’s
normal. A differential of more than 15 psi indicates filters dirty enough to require
replacement.
If an old gauge still works well, use it. But at the first sign of poor performance,
have your mechanic replace it. A reading of less than 0 is one sign of poor per-
formance (or a burst filter). Another is a sudden decrease or return to 0 pressure dur-
ing operation.
While you’re checking the gauge, make sure
it has non-magnetic spacers, NSN 5310-01-
501-5197, installed. Without the spacers, the
gauge is mounted directly to the steel surface.
That interferes with the gauge’s magnetic
movement and can give you a wrong reading.
Notify your mechanic if the spacers are
missing. He’ll install them between the gauge
and the mounting bracket.
Look for spacer behind gauge
I’m old,
worn out,
and about
to be
replaced!
T
he outrigger arms on your M977 and M985 HEMTT are there to steady the truck
when using the crane to lift a heavy load. But they can’t do their job if you don’t give
‘em a hand.
Weighty Problem
Some operators want to make sure there’s
no
slippage. They lower the outrigger
arms so far that the back end of the HEMTT is raised slightly.
Problem is, the hydraulics can’t take the strain of the crane’s load plus the weight
of the HEMTT itself. The lines blow and you aren’t lifting anything.
Lower the outrigger arms so that the rear tires have firm contact with the ground,
but do not bulge from the weight. Any more—or less—won’t get the job done.
Sandy Lifts
Soft or sandy soil lets the outrigger pads sink while you load or unload with the
crane. If you’re lifting something heavy, like an MLRS rocket pod or ammo pallet,
the truck could roll over!
So before emplacing the outrigger
arms, stick a couple of 2x12x24 inch
boards under each pad. Semitrailer
ground jack boards, NSN 2510-00-
741-7585, work well, too. The
boards spread out the weight and
keep your truck nice and steady.
Center the boards before lowering
the outriggers. When you’re not
using the boards, stow them in the
cargo bed.
M977, M985 HEMTTs…
Center boards under
pads before lift
Do the
outriggers
look good
to you, msg
half-mast?
sure! as
long as you
don’t mind
a hydraulic
geyser!
New gauge
Old gauge
617. 10-11 (C)
2/28/04
11:33 AM
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