Hydraulic and earth engineering – Earth treatment or control – Shoring – bracing – or cave-in prevention
Reexamination Certificate
2000-03-13
2002-08-20
Will, Thomas B. (Department: 3673)
Hydraulic and earth engineering
Earth treatment or control
Shoring, bracing, or cave-in prevention
C405S259100, C405S259600
Reexamination Certificate
active
06435778
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to supporting the face of a passage in a geological structure, and more particularly, to a truss system for supporting a mine roof and a related installation method.
BACKGROUND OF THE INVENTION
In recent decades, a number of proposals for supporting the face of a passage in a geological structure, such as the roof in an underground mine, have been made. The typical arrangement employs anchors, such as roof bolts, that extend into spaced bores drilled in the face at opposed angles. A support bracket secured to each angled anchor external to the corresponding bore provides support for a horizontally extending truss member. Depending on the particular application, the truss member may be a cable or metal rod, the ends of which are initially secured to the corresponding bracket by hand. Once secured in place such that it spans between the brackets, the truss member is tensioned to compress and provide support for the adjacent face. Typically, tensioning is either completed manually or by using hand-held power tools.
As explained in my prior U.S. Pat. No. 5,755,535, the major shortcomings of prior art systems include: (1) the relatively large number of diverse parts required to form the truss system, which increases the manufacturing cost; and (2) the difficulty in providing the proper tensioning for the truss member to create the desired level of support. Also, most systems require the installer to determine the length of the truss member with some precision prior to installation to ensure full tensioning. Of course, this increases the overall time required for installation, which is often regarded as a critical factor in determining whether a particular truss system is commercially viable.
To overcome these shortcomings, the '535 patent discloses an improved truss system and related installation method that represents in some respects a radical departure from the approach taken in the prior art. This system reduces the number and diversity of parts required by using identical brackets that not only connect with both the anchor and the truss member, but also serve to support the face adjacent to each borehole when the truss member is properly tensioned. During installation, a drive adaptor allows a rotational socket on a drill head of a bolting machine to provide the necessary torque required for tensioning the horizontal truss member (either a cable or metal rod). This fully eliminates the problems associated with manual tensioning or the use of hand-held power tools. Since a lifting mechanism is available to raise the rotational socket/drill head into the desired position, this also reduces the amount of effort required by the installer, as well as the concomitant incidence of fatigue, especially for installations on mine roofs. Finally, instead of a rotary fastener, a split-wedge retainer holds one end of the truss member securely in a frusto-conical passageway formed in the bracket. Since the corresponding end of the truss member need not be threaded, this eliminates the need for precisely determining the length of the truss member required prior to installation to ensure that full tensioning is reliably accomplished. Overall, the result is a simplified, but exceedingly reliable truss system and installation method.
Despite this significant advance set forth in this earlier '535 patent, I have discovered that there exists an opportunity to provide a highly reliable truss system that is even less costly to manufacture, as well as even simpler and less time consuming to install. Of course, one of the major areas for lowering the manufacturing cost and installation time is to reduce even further the overall number, diversity and complexity of the parts required. This includes eliminating the need for specialized adaptors to transmit driving torque from the bolting machine during tensioning. Moreover, the system would still remove not only the need for threading one or both ends of the truss member, but also the need for precisely determining the length of the truss member required prior to installation to ensure proper tensioning. Overall, the resulting truss system would provide full strength support for the face at a lower manufacturing cost and with less installation effort required.
SUMMARY OF THE INVENTION
Keeping the above needs in focus, it is a primary object of the present invention to provide a truss system for supporting the face of a passage in a geological structure that further overcomes the shortcomings and limitations of the prior art systems.
Another object of the present invention is to provide a truss system including spaced borehole anchors carrying truss support brackets positioned in the borehole and at least one truss member that spans between the brackets, wherein the truss member is set up and tensioned by moving either or both of the brackets along its corresponding anchor.
Still another related object of the present invention is to provide a tension-activated truss system wherein the force for moving the truss support brackets along the corresponding anchor and into the borehole is provided by a bolting machine, whereby the need for manual force or hand-held power tools to provide the necessary tensioning action is eliminated.
A further object of the present invention is to provide a truss support bracket that is drawn along an anchor adjacent its borehole and into the corresponding borehole during tensioning, while a separate face support or plate carried by the truss member engages and supports the adjacent face of the passage.
Yet another object of the present invention is to provide a preferred truss system wherein at least one of the truss support brackets is capable of taking up any slack in the truss member prior to tensioning, even when in position in the borehole, thereby eliminating the need for precisely determining the length of the truss member required prior to installation.
A related, but more specific, object of the present invention is to provide a truss support bracket that carries a split wedge retainer for receiving and capturing an end portion of the truss member, whereby the need for threading the corresponding end of the truss member for receiving a rotary fastener or the like is eliminated.
Still a further object of the present invention is to provide a related method of installing a truss system wherein only a selected one of the truss support brackets needs to move along the corresponding anchor into the borehole after initial set up of the system in order to tension the truss member.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, an improved truss system and related installation method are provided for supporting a face of a passage in a geological structure, such as a mine roof. In its broadest aspects, the truss system of the present invention includes first and second anchors that are positioned in spaced boreholes formed in the selected face of the passageway. A truss support bracket is positioned adjacent its borehole on each anchor and held in position by a fastener. At least one truss member, such as an elongate cable, spans between the brackets, and a motive device is provided for engaging a selected one of the fasteners to move the associated bracket further along the anchor and deeper into the corresponding borehole. As should be appreciated, as the bracket moves deeper into the borehole, the truss member is tensioned to compress and provide support for the adjacent face of the passage.
In the preferred embodiment, the selected f
King & Schickli PLLC
Mayo Tara L.
Triad Support Systems, Inc.
Will Thomas B.
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