30-foot slide section with a sheave head assembly. A
universal sliding boom tip connector, slipped into the
30-foot slide section, connects to the boom tip (fig.
12-55). The sliding boom tip connector swivels,
allowing for driving batter piles in all directions.
The boom is lowered over the leads when
connecting the boom tip to the sliding boom connector.
The connector is bolted into the 30-foot slide section at
the location dictated by the amount of lead extension
desired above the boom tip.
NOTE: Extension of the lead over the boom tip
must not exceed one third of the total lead length or up
to 25 feet maximum.
Figure 12-55.-Sliding boom tip connector.
Figure 12-56.-Extended four-way lead.
The boom is raised to raise the leads. The type of
catwalk used is a hydraulic or mechanical parallelo-
gram bottom brace. This type of brace allows for a
fixed radius or side-to-side batter by swinging the linked
parallelogram in the desired position. The
parallelogram allows for pile driving in all directions at
the bottom. Figure 12-56 shows an extended four-way
lead.
The boom point sheaves are not used to
accommodate the pile-driving hammer and the piles.
The extended four-way leads are equipped with a special
sheave head assembly (fig. 12-57) that the two-hoist
drum wire rope reeves through to support the
pile-driving hammer and the piles.
ADVANTAGES.— Some advantages of using an
extended four-way lead are as follows:
Figure 12-57.-Sheave head assembly.
12-40
