Page 155 - Moving the Earth_ The Workbook of Excavation

ROCK, SOIL, AND MUD

ROCK, SOIL, AND MUD 3.49

FIGURE 3.40 Raising by an anchored bucket.

The same procedure can be used if one track is bogged and the other one is free.
If the shovel is down all around, trenches can be dug to permit bracing under one end. This is used
as a pivot to raise the other end, which is then shored up. The boom is swung to an anchor on the
opposite side, and the hoisting and blocking repeated.
Two anchors may be chained together for greater strength, or to secure a better direction of pull.
If no anchors are located in the proper direction, and it is not practical to make one, the bucket
can be used as counterweight. The dump cable is shortened to permit holding a load far out. A
bucketful of the heaviest dirt available is dug, the boom lowered so that the bucket can be held
just above the ground. Rocks or weights are piled on the bucket until the shovel tips. If the rear of
the tracks is not high enough, it can be brought up by raising the boom.
In any blocking work a loose track is a nuisance, as it will hang down and impede placing of
supports. The slack can be readily taken out by placing a jack on the track frame and raising the
upper section.

Drum Line. A shovel can sometimes pull itself out of trouble by a line attached to one of its
own drums, or to a drag bucket. These lines are too fast for a smooth, steady pull, and the drums
are so high that there is a tendency to pull the front of the shovel down. Better results will therefore
be obtained if the line is passed through a pulley chained to the anchor, and back to the bottom of
the dead axle. If several pulleys are available, and all additional lines run to the dead axle, a very
powerful, well-directed pull will be obtained.
Jamming Chains. A special precaution to be observed with shovels is to keep the drive chains
free from material of any kind. Stretching or jamming these with mud, gravel, or debris not only is
a severe strain on the chain, but also by increasing friction within the chain and with the sprockets
absorbs a large part of the drive power needed at the tracks.

Straddling. It is risky to work a shovel that is straddling a stump or boulder, unless the ground
is known to be entirely firm. The rhythm of load, swing, and rebound causes the tracks to work