Abstract: A reciprocating hammer with a two-stage acceleration of a pile driving ram, including a first stage in which initial gravitational acceleration is assisted by a thruster and a second stage in which the initially accelerated ram is allowed to further accelerate under the force of gravity alone for the remainder of the pile driver stroke. The force assist in the initial acceleration stage acts as a force multiplier, such that the anvil delivers impact forces to the pile greater than the impact forces achievable by gravity alone for a given stroke length/ram weight combination.

Abstract: A vibratory pile driver configured to insert curved sheet pile beneath a conduit by rotating the pile driver about a fixed pivot element to advance the curved sheet pile along a fixed arc. In one exemplary embodiment, the distance between the fixed pivot element and the clamps that secured the curved sheet pile to the pile driver is the same as the radius of curvature of the curved sheet pile. In another exemplary embodiment, when the curved sheet pile is secured to the pile driver by the clamps, the center of the radius of curvature of the curved sheet pile lies substantially on the rotational axis of the fixed pivot element. In this embodiment, the vibratory pile driver may be rotated about the fixed pivot element to advance the curved sheet pile along an arc having curvature substantially identical to the radius of curvature of the curved sheet pile.

Abstract: An apparatus and method for the subterranean support of underground conduits is disclosed, including a pile driver that is configured to connect to an articulated boom of an excavator or another unit of positioning machinery to insert a section of curved sheet pile beneath a conduit. In one exemplary embodiment, the pile driver has a head portion and a body portion. The head portion of the pile driver is connected to the excavator and the body portion of the pile driver is moveable relative to both the head portion of the pile driver and the excavator to allow the pile driver to properly orient a section of curved sheet pile for insertion into subterranean material beneath an underground conduit.

Abstract: An apparatus and method for the subterranean support of underground conduits is disclosed, including a pile driver that is configured to connect to an articulated boom of an excavator or another unit of positioning machinery to insert a section of curved sheet pile beneath a conduit. In one exemplary embodiment, the pile driver has a head portion and a body portion. The head portion of the pile driver is connected to the excavator and the body portion of the pile driver is moveable relative to both the head portion of the pile driver and the excavator to allow the pile driver to properly orient a section of curved sheet pile for insertion into subterranean material beneath an underground conduit.

Abstract: A vibratory pile driver configured to insert curved sheet pile beneath a conduit by rotating the pile driver about a fixed pivot element to advance the curved sheet pile along a fixed arc. In one exemplary embodiment, the distance between the fixed pivot element and the clamps that secured the curved sheet pile to the pile driver is the same as the radius of curvature of the curved sheet pile. In another exemplary embodiment, when the curved sheet pile is secured to the pile driver by the clamps, the center of the radius of curvature of the curved sheet pile lies substantially on the rotational axis of the fixed pivot element. In this embodiment, the vibratory pile driver may be rotated about the fixed pivot element to advance the curved sheet pile along an arc having curvature substantially identical to the radius of curvature of the curved sheet pile.

Abstract: An apparatus for impacting on a hard surface such as concrete so as to break up the hard surface. This apparatus comprises a frame having a bed and an upstanding rail assembly projecting from the bed, a drive shoe, a hammer means attached to the rail assembly so as to be movable in only one direction and operatively connected to the drive shoe for impacting upon the drive shoe. The drive shoe lies adjacent the surface so that upon impact from the hammer means, the shoe forcefully impacts the surface so as to break up the surface. An adjustment means is used to selectively position the drive shoe relative to the hammer means.