The steps required to install the hammer in the leads
in the horizontal position are as follows:
1. Block the leads about 18 inches off the ground
in several places, keeping them as level as possible.
2. Using a forklift, place the hammer at the base of
the leads with the top of the hammer towards the top of
the leads.
NOTE: On underhung leads, the fuel pump faces
upward. On extended four-way leads, the fuel pump
faces downward.
3. Have the forklift approach the hammer from the
pile cap end.
4. Adjust the forks so they will just fit the lead
guides on the hammer.
5. Pick the hammer up in this manner and guide the
top end into the leads as far as it will go without hitting
the forks.
6. Block up the hammer that protrudes and
reposition the forklift to push the remainder of the
hammer into the leads.
NOTE: The crane line may assist in pulling the
hammer into the leads.
7. Secure the hammer to the bottom of the leads.
This will keep the strain off of the leads, as they are
raised to the vertical position by the crane boom.
Installing the hammer in the leads in the vertical
position is as follows:
1. Raise the boom and leads from horizontal to
vertical and install the catwalk. Continue to raise the
boom as high as practical and safety permits.
2. Hoist the hammer to a vertical position and
position it under the leads. It takes a combination of
lowering the boom and hoisting the hammer to slide the
hammer onto the lead guides.
If this does not allow enough clearance to install the
hammer vertically, use the following:
1. Use a deep ditch or loading ramp for additional
clearance for the hammer.
2, Set the hammer in an excavated hole to clear the
bottom of the leads.
3. The hammer can be partially submerged in water
to gain additional clearance.
PILE-DRIVING TECHNIQUES AND
TERMINOLOGY
Care must be taken during pile driving to avoid
damaging the pile, the hammer, or both. The pile driver
must be securely anchored to avoid a shift of position.
If the hammer shifts while driving, the blow of the
hammer will be out of line with the axis of the pile and
both the pile and hammer may be damaged.
Carefully watch the piles for any indication of a split
or brake below the ground. If driving suddenly becomes
easier or if the pile suddenly changes direction, a break
or split has probably occurred. When this happens, the
pile must be pulled.
Springing and Bouncing
“Springing” means that the pile vibrates too much
laterally from the blow of the hammer. Springing may
occur when a pile is crooked, when the butt has not been
squared off properly, or when the pile is not in line with
the fall of the hammer. In all pile-driving operations,
ensure the fall of the hammer is in line with the pile axis;
otherwise, the head of the pile and the hammer may be
damaged and much of the energy of the hammer blow
is lost.
Excessive bouncing may come from a hammer
which is too light. However, it usually occurs when the
butt of the pile has been crushed or broomed, when the
pile has met an obstruction, or when the pile has
penetrated to a solid footing. When a double-acting
hammer is being used, bouncing may result from too
much steam or air pressure. With a diesel hammer, if
the hammer lifts on the upstroke of the ram piston, the
throttle setting is probably too high. Back off on the
throttle control just enough to avoid this lifting. If the
butt of the timber pile has been crushed or broomed
more than an inch or so, it should be cut back to sound
wood before driving operations continue.
Driving Bearing Piles in Groups
Bearing piles are frequently driven in groups, as in
a pile group which will support a column footing for a
building or in closely spaced rows, as beneath a wall.
When piles must be driven in closely spaced groups,
these principles are observed:
1. When a pile is driven into sand or gravel
deposits, the soil must be compacted or displaced an
amount equal to the volume of the pile. If the deposit is
quite loose, the vibration of pile driving frequently
results in considerable compaction of the soil. The
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