MAST AB-1386/U - NSN 5985-01-381-6341

Total mast height is variable from 8.3 to 33.1 ft (2.5 to 10.1 m) with all mast sections fully deployed. Accessories are provided to assist with guying, anchoring, and operating the mast in its ground mount configuration. They include a hammer, a tripod, guy assemblies, guy stakes, baseplate stakes, crank handle, baseplate, and a radius rope.

Two mounting kits may be used to adapt the HMMWV and the tracked vehicle with brackets and hardware to deploy the mast. The mounting kits are used to anchor the mast to the vehicle and to stabilize the mast when deploying it under normal conditions (i.e., winds below 25 mph [40 kph]).

GearBox Rebuild

Disassembly

There are 6 hex head screws on the bottom of the box. Remove these screws and carefully pry the lid off. Be sure the equally lift from all side and work it off, so it doesn't jam on the shafts.

Bearing Removal

Gearbox with Old Bearing

Gearbox with New Bearing

Upon removal there is a large bearing, I had to replace this, as mine was frozen up. the proper replacement bearing is a Koyo #62052RDC3. You will need a press to do this..

New bearing with old backing and bushing

Remove the bearing from the housing
Lightly tap the bearing while holding the outer ring to remove it (the one with the notch)
Place the bearing in the press or suitable jig, and knock the brass bushing out from the rear.
Remove the aluminum backing is attached to the bearing in the center, this wasn't meant to be re-used, so you will have to cut the bearing from around it. I tried using different pullers, but the aluminum will bend and deform, before the bearing is removed.
Once this is cut off you can press this into the new bearing and re-install it.

box turns, but wont raise or lower the tower

this is usually due to the center shaft notch no longer being tight. When the shaft is turned, this also turns and wont turn the large screw on the tower.

I attempted to resolve this many ways,

I tried..

- dimpling the edge to make it tight

- jb weld

- wedging it from the back

Welding was the only one that worked. What you dont want, which i was privileged enough to experience, is to get the tower up, then have this loosen up again, and have no way to lower it. Weld it, you don't want this problem.. trust me.