![]() The energy moves the ram upward, and in some hammers, downward as well. These hammers have external power sources such as the crane, steam boilers, air compressors, and/or hydraulic power packs. External Combustion HammersĮxternal combustion hammers burn the fuel that provides the energy for the operation outside of the hammer itself. The stroke of a pile- driving hammer is usually between three and ten feet (900 to 3000 mm). It transfers a large portion of the kinetic energy of the ram into the pile. The ram must have a mass and impact velocity that is sufficiently large to move the pile.Ī properly functioning hammer strikes the pile in quick succession. Impact pile driving hammers consist of a ram and an apparatus that allows the ram to move quickly upwards and then fall onto the driving system and pile. Double acting hammers were developed in order to speed up operations. These developments included rams that were raised by ropes through human or horse muscle, those hoisted by steam winches or powered by steam, air, or hydraulic pressure, and finally the diesel hammer. Over the years, technology has advanced toward the development of larger and faster hammers. Selection of a hammer should consider the anticipated driving resistance, ultimate capacity, pile stresses expected during driving, and soil set-up. The realization that some hammer types may cause reduced capacities for identical pile lengths.The ability to obtain penetration rates within the desired band.The ability to drive the pile without structural damage or reducing soil capacity.The need to use pile penetration rate as the means to end driving.The hammer’s interaction with the pile-soil system is both modeled before driving (wave equation analysis) and monitored during pile installation (pile driving analyzer). The vertical advance of a pile under a given hammer blow is used as a measure of the pile’s bearing capacity. When it comes to pile driving, a hammer isn’t just a hammer. In some installations only one hammer type may be applicable for the pile-soil combination, while for others several types may be suitable. Identify the broadest possible selection of hammers for the job. Hammer selection is the most important aspect of pile installation. It is typically made of several layers of plywood. The helmet, which aligns the pile head and hammer.The hammer cushion, which protects both the hammer and the pile from excessive stress.The lead, also called the set of leads, sometimes including a brace that allows for the adjustment of the lead angle.All components of the driving system have some effect on the performance of a hammer and/or how the hammer transfers its energy to a pile.
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