The process starts by getting some space. Lots of
space. A 10 acre field works nicely! |
Get it in position and then lower the boom. |
The big yellow main hook block weighs 5,000 lbs and
the ball about 1300 lbs. These guys wrestle it over into position on the
bed of the truck. No sudden moves and watch your toes! |
Next, unthread the cables but thread it's not - 1
inch steel. |
With the hoist cables out of the way, ease the top of
the boom onto the trailer. |
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As the operator lets the trailer take the weight of
the boom, the supporting pendant cables back to the hydraulics go slack
and a rigger disconnects them.
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The rigger has attached short cables from top of the
boom hydraulics to the support truss for the guide sheaves at the butt of
the boom. The operator can now support the boom from the butt end so the
sections can be unpinned.
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Unhook the pendants and top pins.
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Swing that sledge and knock out the bottom pins. |
Tie it down.
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The operator backs the 777 a little and the top
section is free. |
Take it away.
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Bring on another truck and let's get the next
section.
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Same song, second verse. |
Going......
.......
Going...... |
Gone! |
This boom section is 40 feet long, 7 feet wide, 6
feet high and with the pendants weighs only 4,300 pounds.
The 777 is configurable with different length booms.
Three of these sections comprise the center of the boom for the crane on
this site. |
To finish the work, we need to rig a small hook
block. |
Like This. Now the 777 has what it needs to complete
it's own disassembly. |
The next step is to rig cables to the main
counterweight . |
After removing the pins that attach the weights to
the upper works, all 140,000 pounds are gently lowered to the ground using
the boom hydraulics. |
70 tons on the ground, now unhook the cables. |
Now we remove the counterweights attached to the
carbody (the framework between the crawlers). These are 22,000 lbs each. |
And load them on the truck. |
Last one. |
Take the main counterweight apart. Each block is
17,500 lbs. |
That's half of them. |
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52,500 lbs is a full load.
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The bottom plate or tray weighs 35,000 lbs. |
Disconnect the telescoping drive shafts from each
crawler. Now we're not going anywhere! |
What's this? Stilts? Yep - another trick the 777
knows is to rise up on hydraulic rams - essential if you're removing the
crawlers like these riggers connecting the chains. |
With the chains attached and the pins pulled, one of
the 35,000 pound crawlers is broken free. |
Lift it and back a trailer under it. |
One crawler gone and one to go. |
With the first crawler gone, and no counterweights,
maintaining balance on this last lift is tricky. Watch that boom angle! |
Oops! But no harm done. |
A few small adjustments and the last crawler is ready
to go. |
One of the 17.5 ton crawlers. |
Almost done. Everything that can be detached is gone.
What do you do with this 86,000 lb upper works module? |
Of course - get another truck. This one is a special
low boy that can handle the 43 ton load. |
Ease it down, secure it and it's off to the next job. |
