Patent ID: 8763719
Filing Date: 2014-07-01
Classification: E02D

Abstract:
1. A drop hammer for driving a pile comprising: a housing assembly defining a drive axis, a main chamber, and a plurality of vent openings that allow fluid to flow into and out of the main chamber, where a hammer supported within the main chamber for movement relative to the housing assembly between an upper position and a lower position, where the first and second vent locations are located between the upper and lower positions; a helmet member supported by the housing assembly for movement relative to the housing assembly between a first position and a second position; a lifting system capable of being operatively connected to and detached from the hammer, where the lifting system at least one plug; whereby when the hammer drops and is above the first vent location, ambient air flows from the main chamber through the vent openings formed at the first and second vent locations; when the hammer drops and is below the first vent location and above the second vent location, ambient air flows from the main chamber through the vent openings formed at the second vent location; when the hammer drops and is below the second vent location, air within the main chamber is compressed to preload the helmet member prior to contact between the hammer and helmet member; and the pile driving system operates in