The steps required to install the hammer in the leadsin the horizontal position are as follows:1. Block the leads about 18 inches off the groundin several places, keeping them as level as possible.2. Using a forklift, place the hammer at the base ofthe leads with the top of the hammer towards the top ofthe leads.NOTE: On underhung leads, the fuel pump facesupward. On extended four-way leads, the fuel pumpfaces downward.3. Have the forklift approach the hammer from thepile cap end.4. Adjust the forks so they will just fit the leadguides on the hammer.5. Pick the hammer up in this manner and guide thetop end into the leads as far as it will go without hittingthe forks.6. Block up the hammer that protrudes andreposition the forklift to push the remainder of thehammer into the leads.NOTE: The crane line may assist in pulling thehammer into the leads.7. Secure the hammer to the bottom of the leads.This will keep the strain off of the leads, as they areraised to the vertical position by the crane boom.Installing the hammer in the leads in the verticalposition is as follows:1. Raise the boom and leads from horizontal tovertical and install the catwalk. Continue to raise theboom as high as practical and safety permits.2. Hoist the hammer to a vertical position andposition it under the leads. It takes a combination oflowering the boom and hoisting the hammer to slide thehammer onto the lead guides.If this does not allow enough clearance to install thehammer vertically, use the following:1. Use a deep ditch or loading ramp for additionalclearance for the hammer.2, Set the hammer in an excavated hole to clear thebottom of the leads.3. The hammer can be partially submerged in waterto gain additional clearance.PILE-DRIVING TECHNIQUES ANDTERMINOLOGYCare must be taken during pile driving to avoiddamaging the pile, the hammer, or both. The pile drivermust be securely anchored to avoid a shift of position.If the hammer shifts while driving, the blow of thehammer will be out of line with the axis of the pile andboth the pile and hammer may be damaged.Carefully watch the piles for any indication of a splitor brake below the ground. If driving suddenly becomeseasier or if the pile suddenly changes direction, a breakor split has probably occurred. When this happens, thepile must be pulled.Springing and Bouncing“Springing” means that the pile vibrates too muchlaterally from the blow of the hammer. Springing mayoccur when a pile is crooked, when the butt has not beensquared off properly, or when the pile is not in line withthe 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 bedamaged and much of the energy of the hammer blowis lost.Excessive bouncing may come from a hammerwhich is too light. However, it usually occurs when thebutt of the pile has been crushed or broomed, when thepile has met an obstruction, or when the pile haspenetrated to a solid footing. When a double-actinghammer is being used, bouncing may result from toomuch steam or air pressure. With a diesel hammer, ifthe hammer lifts on the upstroke of the ram piston, thethrottle setting is probably too high. Back off on thethrottle control just enough to avoid this lifting. If thebutt of the timber pile has been crushed or broomedmore than an inch or so, it should be cut back to soundwood before driving operations continue.Driving Bearing Piles in GroupsBearing piles are frequently driven in groups, as ina pile group which will support a column footing for abuilding 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 graveldeposits, the soil must be compacted or displaced anamount equal to the volume of the pile. If the deposit isquite loose, the vibration of pile driving frequentlyresults in considerable compaction of the soil. The12-48
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