Page 147 - Moving the Earth_ The Workbook of Excavation

ROCK, SOIL, AND MUD

ROCK, SOIL, AND MUD 3.41

should be used with caution. If the stuck machine has not sunk but has simply lost traction on a
slippery surface, power can usually be applied without damage. However if it is sunk in badly,
use of moderate power may be useless, and too much power may pull it apart.

TRUCKS

Dump trucks are probably the most frequently stuck type of equipment. If one is loaded, it may
be possible and desirable to dump the load, after which the truck may pull out under its own
power. But if the truck is tipped sideways, as with one pair of rear wheels bogged down, the other
resting on the surface, the raising of the load preparatory to dumping increases the sideward
strain, and may overturn the truck (as shown in Fig. 3.31) or tear the body off its base. A winch
cable attached to the front top of the body on the high side, and pulling uphill, may permit dump-
ing of a tipped truck, but even with skillful operation, the strain on the body is considerable.
Unloading by hand, or partial unloading by power shovel, hoe, or front loader may be necessary.
A shovel is a highly effective rescuer of bogged trucks. A front bucket may be placed under the
rear of the frame (or, with some risk of damage, under the rear of the body) and may lift and push
at the same time. A front loader can do the same, but might walk into the same mudhole; and its
wider bucket may be blocked by tires. A dozer has the same problems.
A hydraulic hoe can get most of the load out of the body, then push and lift with the back of
its bucket.
Digging Out. If the truck cannot be emptied, or is empty and is still stuck, and no powerful
equipment is at hand, the next procedure is to dig out the wheels in the direction toward which it is
hoped to move. Two-wheel-drive trucks have best traction going forward, and in many situations,
such as sinking in a soft shoulder, an attempt to back out will cause the front wheels to get in
worse difficulties. Any digging helps, but the best procedure is to go to the bottom of all tires,
make a ramp up to the surface with a length of 3 feet or more to every foot of depth, and put a
board or boards on this slope, with the lower end against or under the tire. If boards are not available,
matted brush, stones, gravel, or anything but mud may be used. If the axles or frame is resting on
the ground, an attempt should be made to free them, but this is not often possible. See Fig. 3.32.
Even if this digging does not enable the truck to get itself out, it makes it much easier for a
light machine to pull it, and it greatly reduces the danger of damage if pulled by a large machine.
Breakage. Applying brute force to pulling a deeply bogged truck may result in getting it out
minus its rear axle assembly and wheels, a partial victory that brings little satisfaction. In most
trucks the rear axle is attached to the frame only by the spring shackles and propeller shaft.

FIGURE 3.31 Dumping on a side slope.