Figure 7-38.Dumping the load.
reading and understanding the operators manual for the
model of dump truck you are assigned to operate. This
section covers the basic characteristics and operations
of dump trucks.
A typical dump truck is equipped with a dump body
that is hinged to the rear of a subframe which is mounted
directly on the truck chassis. Dump bodies range in
structural strength and size to support different
operations. That is why it is important that the operator
knows the design and capacity of the dump truck
assigned to operate. You do not want to haul quarry rock
in a dump body designed to haul and heat asphalt. The
quarry rock can damage the dump body and render it
useless for asphalt operations. The components of a
dump truck body are shown in figure 7-36.
A hydraulic hoist assembly is used to raise and
lower the dump truck body. The hydraulic pump is
driven by a propeller shaft connected to the power
takeoff (PTO). A variety of ways are used to engage the
PTO on dump trucks used in the NCF; therefore, consult
the operators manual for specific instructions on how
to engage the PTO and hoist assembly.
DUMP TRUCK OPERATIONS
During dumping operations, the truck should be on
level ground or inclined uphill with the front of the truck
facing downward. When the truck is in position, release
the lower latches of the tailgate with the hand lever at
the front left corner of the body (fig. 7-37.) Then engage
the control for the dump truck body. Hydraulic pressure
will begin to hoist the dump truck body, and as the body
rises, the load will slide backward under the open
tailgate (fig. 7-38, view A). If the load piles up and
blocks the tailgate (fig. 7-38, view B), place the truck in
low gear and move it forward until there is more space
to dump the remainder of the load.
If the load does not slide out easily, have someone
dislodge it with a long-handled shovel, taking care not
to stand in the immediate dumping area. When dumping
a load of rocks or other large solids, see that the tailgate
is latched at the bottom, but unfastened at the top, so that
the tailgate can drop down and the load can drop, as
shown in figure 7-39.
Not all dump trucks have tailgate wings. On those
that do not, you have to drop the tailgate down and
support it with chains. To spread a load over a large area,
Figure 7-39.Tailgate rigged for dumping large material.