PS Magazine - TB 43-PS-666
PS, The Preventative Maintenance Monthly
ISSUE 666
MAY 2008
15
PS 666
MAY 08
D
on’t wanna hear a loud boom when using your HEMTT’s boom winch? Then keep
all loads secure by using a good wedge socket to attach the wire rope to the hook.
Whenever your M977, M984A1, and M985 HEMMTs are refurbished, the
safety clamp on the cable is removed. But your vehicle
needs
this safety
clamp because it keeps the wire rope from slipping back past the wedge
and suddenly popping loose from the socket.
If the safety on your HEMMT’s
cable is missing, use a cable clamp
and six inches of wire rope.
Clamping Tips
Never
clamp the dead end of the rope to the live end. The live end should form a
nearly direct line to the clevis pin of the Ftting. Clamping to the live end could add
a wear point, bend the nearly straight line, and keep the wire rope from pulling the
wedge in tight against the socket.
A good way to remember the correct
way to install cable clamps is to remember,
“Never saddle a dead horse.”
The saddle
portion looks like a little horse saddle, so
install the U-bolt on the dead end and the
saddle portion on the three-inch extra piece of
wire rope.
Also, if you decide to use more than one
clamp, make sure they all go on the same way.
That way, the U-bolt won’t damage the live
end of the cable.
Load Testing
TM 9-2320-279-20-1 tells you that load testing of cranes is required before using cranes
that have undergone modiFcation or alteration. So when you’ve done these steps, take
your HEMTT to support for testing. They’ll need to use the guidance in TB 43-0142,
Safety Inspection and Testing of Lifting Devices,
and TB 9-2320-279-34,
Test Procedures,
Direct Support and General Support Maintenance Levels Load Testing Heavy Expanded
Mobility Tactical Truck (HEMTT) Vehicle Cranes.
Cranes that don’t meet load test requirements are NMC.
Clamping Correctly
1.
Make sure there are no rough edges or burrs on the wedge or socket that could
damage the wire rope.
2.
If the end of the rope is welded, cut off that portion. That allows any distortion of the
rope strands—caused by the sharp bend around the wedge—to adjust itself at the end
of the rope.
Wrap steel wire around the end of the
wire rope to keep it from unwinding or
fraying.
Don’t
use heavy-duty tape, since
it’s not strong enough to hold steel and
frayed wires in place.
3.
Thread the rope through the socket,
make a 180° turn, and then thread the
rope back through the other side of
the socket.
Make sure the end of the rope extends
past the socket six to nine times the rope’s
diameter. ±or example, if you’re using
1
/
2
-in
diameter rope, the end needs to extend 3
to 4
1
/
2
inches past the socket. Leaving it
shorter might allow the rope to slip free of
the socket during a lift.
4.
Insert the wedge into the socket.
5.
Clamp the dead end of the rope to the
three-inch piece of rope. Position the clamp,
NSN 4030-00-233-9566, with the dead end
of the rope against the U-bolt and the
short piece against the saddle. Clamp the
two as close to the wedge as possible.
HEMTTs…
Common Sense
for the
Boom WinCh
Position
dead end
against
U-bolt…
…and
short
piece
against
saddle
time for you
to help me
with a lift…
did you
make sure
I can bear
the load?
Correctly
clamped
rope
looks like
this
Wrap steel wire
around ends of
wire rope
A bad clamp job
results in frayed
wires and weak
support.
So follow
these steps
to clamp
correctly…
Don’t leave
dead end
of rope too
short
666.14-15.indd
1-2
3/28/08
5:46:45 PM
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