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Pile driver

Pile driver description/claims

This application is a Division of patent application Ser. No. 11/369,462, filed Mar. 7, 2006, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 60/659,711, entitled PILE DRIVER, filed on Mar. 8, 2005 and U.S. Provisional Patent Application Ser. No. 60/661,104, entitled PILE DRIVER, filed on Mar. 11, 2005, the entire disclosures of which are hereby expressly incorporated by reference herein.

1. Field of the Invention

The present invention relates to pile drivers, particularly with regard to reciprocating pile drivers.

2. Description of the Related Art

Pile drivers are used to drive piles, such as beams, columns or supports, e.g., into the ground. Reciprocating pile drivers include a hammer that is placed onto the head, or top, of the pile by a hoist or a boom of, e.g., an excavator. The hammer typically includes a frame and a large ram, or weight, that is raised within the frame and then dropped onto the pile head. This process is repeated until the pile is driven into the ground to a desired depth. Commonly, a pneumatic or hydraulic cylinder is mounted to the frame to raise and then release the ram. However, in existing hammers, as the ram strikes the pile, significant forces are transmitted into the cylinder through a cylinder rod attached to the ram. As a result, these cylinders frequently break resulting in significant downtime and cost to replace the cylinder. Some existing hammers include a nylon or rubber mount at the connection between the ram and cylinder rod to dampen these forces, however, these mounts can deteriorate quickly.

As the pile is driven downwardly, the hammer frame is typically positioned on top of the pile or a drive cap positioned on top of the pile. If the frame does not rest on top of the pile or drive cap, the ram may strike the frame instead of the pile thereby transmitting the force of the falling ram into the frame. This force may be transferred from the frame into the boom of an excavator, e.g., causing damage to the excavator and possibly causing the excavator to tip over. Some previous hammers had to be lowered after each strike of the ram to keep the hammer frame in contact with the pile head. Other hammers were lowered within a large, elongate outer frame to keep the hammer frame in contact with the pile head. However, these outer frames required significant overhead room to position the hammer, thus, pile drivers utilizing these outer frames were mostly limited to outdoor applications.

What is needed is an improvement over the foregoing.

One aspect of the invention includes a mounting apparatus for connecting a ram lifting mechanism to a ram of a hammer. In one embodiment, the mounting apparatus includes a connector member that is connected to the ram and a cable extending between the connector member and a cylinder rod extending from a cylinder. In operation, the cable is drawn taut as the cylinder raises the ram, however, the cable is permitted to flex or deform when the ram strikes the pile. Thus, very little of the force created by the ram impacting the pile is transmitted into the cylinder. In one embodiment, the connector member includes a flange that is captured between the ram and a retaining cap that is fastened to the ram.

Another form of the invention includes an apparatus for allowing relative movement between the hammer and, e.g., the boom of an excavator. In one embodiment, the apparatus includes at least one frame rail mounted to the hammer frame and a mounting plate assembly that interfits with and is slidable with respect to the frame rail mounted to the boom of an excavator. In one embodiment, the mounting plate assembly includes a recess that envelops the frame rail. In an alternative embodiment, the mounting plate assembly is enveloped by the frame rail. In the present embodiment, the mounting plate assembly interfits with the frame rail in such a way that the mounting plate assembly can slide along an axis defined by the rail. The mounting plate assembly can be further constructed to prevent substantial relative movement between the hammer and the mounting plate assembly transverse to the rail axis. In a further embodiment, the apparatus can permit relative rotational movement between the hammer and the boom of an excavator. This embodiment may be helpful when the excavator is sitting on an inclined surface.

In operation, in one form of the invention, the hammer is placed on top of the pile and, as the pile is driven downwardly, the hammer follows the pile owing to the relative movement between the excavator boom and the hammer. Advantageously, the hammer can follow the pile without requiring continuous downward readjustment of the boom. However, the boom is adjusted periodically when the mounting plate reaches an end of the hammer frame rail. As a result, the possibility of operator error is reduced as fewer adjustments of the boom are required. Further, pile drivers incorporating this apparatus are an improvement over existing pile drivers as the possibility of the ram striking the frame is also reduced. In one embodiment, the mounting plate assembly does not extend substantially above the hammer frame. This embodiment provides an added advantage of allowing the hammer to be used inside buildings, etc, having very little overhead room.

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following descriptions of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a hammer in accordance with the present invention positioned on top of a pile by an excavator boom;

FIG. 2 is a perspective view of a hammer in accordance with the present invention;

FIG. 3 is a fragmentary cross-sectional view of the hammer of FIG. 2;

• Provisional Patent
• Utility Patent

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