Abstract: A pile driving device of the drop hammer variety is disclosed and includes a crane supportable housing containing a hydraulic drive motor and a cam member for executing generally circular motion within the housing in response to operation of the drive motor and a ram depending from the housing of a substantial mass and having a bearing plate selectively engageable by the cam with cam motion sequentially raising the ram and disengaging the bearing plate to allow the ram to free fall and impact a pile. Also depending from the housing is a vertical guide arrangement for limiting ram motion to generally vertical reciprocating motion limited at one end by the pile being driven and at the upper extreme by the uppermost position of the cam member. The drop hammer assembly may further include a sleeve which is removably attachable to a pile upper end and which extends upwardly therefrom to provide a sleeve portion in which the ram may reciprocate.