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Common sense for the boom winch.


Don'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 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[degrees] 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. For 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.


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 fitting. 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 modification 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.
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Title Annotation:HEMTTs ...; Heavy Expanded Mobility Tactical Truck
Publication:PS, the Preventive Maintenance Monthly
Geographic Code:1USA
Date:May 1, 2008
Previous Article:Get your tires from DLA.
Next Article:CTIS NMC criteria and tire pressure info.

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