Pile Driver Types, Components, and Terminology
What this domain covers
Pile Driver Types, Components, and Terminology tests recognition of hammer families, load-path components, and the vocabulary used in plans and signals.
Hammer types
- Drop hammer: heavy weight raised and released; simple but slow and imposes shock.
- Diesel hammer: self-contained, uses fuel ignition and ram stroke; single- or double-acting.
- Hydraulic hammer: hydraulic ram, adjustable energy and stroke; common for concrete and sheet piles.
- Vibratory driver: counter-rotating eccentric weights; effective in granular soils and for sheet piles; also used for extraction.
- Air/steam hammer: external power; older technology.
Load path and terms
The hammer strikes a helmet or pile cap through a cushion and anvil. The pile cap or driving shoe protects the pile head. Leads guide the pile and hammer; fixed leads attach to the crane, hanging leads hang from the boom. A lead spotter at the pile tip aids alignment. Batter or rake is the pile's angle from vertical; plumb means vertical. A follower transmits energy when the pile head is below the leads. Cutoff is the final pile elevation.
Worked example
A sheet-pile wall in loose sand is being installed. A vibratory hammer is selected because it drives by vibration and can extract sheets; a diesel hammer would add high impact and noise. The contractor still checks the manufacturer's permitted pile section, clamp force, and crane capacity with the vibratory unit and power pack included.
Traps
Confusing a helmet with a pile cap; assuming every hammer can drive every pile section; forgetting that the vibratory power pack and clamp are attachments with weight; and calling a batter pile plumb because it looks nearly vertical.