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 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 pile driver including an apparatus for allowing relative movement between a hammer and a boom of an excavator. The apparatus includes a mounting plate mounted to the boom that interfits with and is slidable with respect to a frame rail mounted to the hammer. In operation, the hammer is placed on top of a pile and, as the pile is driven downwardly, the hammer follows the pile. Owing to the relative movement between the boom of the excavator and the hammer, the hammer follows the pile without requiring continuous downward readjustment of the boom. In one embodiment, the mounting plate assembly does not extend substantially above the hammer frame. In another embodiment, the hammer can rotate with respect to the boom. In one embodiment, the hammer includes a ram, a cylinder for lifting the ram, and rotation-resistant cable connecting the ram and the cylinder.

Abstract: A pile driver including an apparatus for allowing relative movement between a hammer and a boom of an excavator. The apparatus includes a mounting plate mounted to the boom that interfits with and is slidable with respect to a frame rail mounted to the hammer. In operation, the hammer is placed on top of a pile and, as the pile is driven downwardly, the hammer follows the pile. Owing to the relative movement between the boom of the excavator and the hammer, the hammer follows the pile without requiring continuous downward readjustment of the boom. In one embodiment, the mounting plate assembly does not extend substantially above the hammer frame. In another embodiment, the hammer can rotate with respect to the boom. In one embodiment, the hammer includes a ram, a cylinder for lifting the ram, and rotation-resistant cable connecting the ram and the cylinder.

Abstract: A pile driver including an apparatus for allowing relative movement between a hammer and a boom of an excavator. The apparatus includes a mounting plate mounted to the boom that interfits with and is slidable with respect to a frame rail mounted to the hammer. In operation, the hammer is placed on top of a pile and, as the pile is driven downwardly, the hammer follows the pile. Owing to the relative movement between the boom of the excavator and the hammer, the hammer follows the pile without requiring continuous downward readjustment of the boom. In one embodiment, the mounting plate assembly does not extend substantially above the hammer frame. In another embodiment, the hammer can rotate with respect to the boom. In one embodiment, the hammer includes a ram, a cylinder for lifting the ram, and rotation-resistant cable connecting the ram and the cylinder.