cases, a drive chain reduction. In most lattice boom
cranes, the engine is mounted in the crane house.
COUNTERWEIGHT. The counterweight on
the rear of the crane house creates additional stability
when lifting loads. The counterweight rotates with the
house as it swings. Most counterweights are removable
to reduce the overall weight of the crane for transporting.
Part of your prestart inspection is to check the
Lattice Boom Breakdown
The bridle assembly plays an important part when
changing the length of the boom. If you forget to
disconnect the boom pendants lines from the boom tip,
and not connect the bridle assembly or pendant lines
behind the boom section you plan to remove or install,
and you drive out the bottom pins, the top pins will act
as a hinge and the boom will fall, as shown in figure
12-23. If you make this mistake and a crew member is
under the boom, a tragedy could result, as shown in
NEVER WORK UNDER A CRANE
BOOM. Because so many accidents have
occurred while personnel were changing
booms, some manufacturers have made a
one-way connecting pin that can only be
installed from the inside. This requires the pin
to be removed only from the outside, keeping
personnel from getting underneath the boom
(fig. 12-25). A common practice in the NCF is
to install the pins from the inside out to prevent
personnel from maneuvering inside the boom
to drive out the pins.
Several methods are used to break down lattice
booms to add or take out sections. If the boom sections
Figure 12-24.-Never work under a crane boom.
Figure 12-25.-Drive pins from the outside in.
are bolt-connected, you must use dunnage for support
under each section.
The most common boom connection is with pins.
To break down a pin-connected boom, make sure you
Figure 12-23.Incorrect way to disconnect the lattice boom.