Hydraulic and earth engineering – Earth treatment or control – Shoring – bracing – or cave-in prevention
Reexamination Certificate
1999-07-02
2001-06-26
Pezzuto, Robert E. (Department: 3671)
Hydraulic and earth engineering
Earth treatment or control
Shoring, bracing, or cave-in prevention
C405S284000, C405S288000
Reexamination Certificate
active
06250849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cribbing system such as for supporting a mine roof. More particularly, the present invention relates to a wooden interconnected cribbing system which maximizes bearing surface contact area between adjacent cribbing members.
2. Background Information
Wooden cribbing systems have long been used for supporting mine roofs and the like. Typically, a cribbing system is a column type structure formed by several layers of overlapped cribbing elements. Individual cribbing elements have been called cribs, blocks and logs. The interconnection of overlapping cribbing elements has been accomplished by notching of one or both of adjacent cribbing elements. Examples of this interconnection can be found in U.S. Pat. Nos. 400,693; 710,115; 1,312,331; 1,704,941; 1,707,224; 1,749,303; 4,664,562; 4,840,003; 4,997,315 and 5,746,547. The interconnection of adjacent cribbing elements prevents slippage between adjacent cribbing elements which will maintain proper contact between the bearing surfaces thereof. The bearing surface generally refers to the area of the cribbing element which transfers the load to an adjacent cribbing element. In many cribbing systems, only the corner crossing points are load bearing or bearing surfaces. Cribbing systems have been designed to increase or maximize the bearing surface between adjacent cribbing elements. For example, the cribbing system disclosed in U.S. Pat. No. 5,746,547 has substantially the entire surface of the cribbing elements acting as a bearing surface.
The existing cribbing systems include disadvantages. The overlapping arrangement of many designs results in overhanging portions which can prematurely fracture or incur undue stresses. The notching orientation may limit the load carrying capabilities of the cribbing system even where the entire surface of the cribbing element acts as a bearing surface.
It is an object of the present invention to overcome the aforementioned difficulties with the prior art. It is a further object of the cribbing system of the present invention to provide a cribbing system which maximizes the bearing surfaces of the cribbing elements. Another object of the cribbing system of the present invention is to provide a cribbing system with minimal components that is easy to assemble and manufacture.
SUMMARY OF THE INVENTION
The above objects are achieved with a cribbing system according to the present invention. The cribbing system according to the present invention includes a multi-sided column with each side formed of a stack of cribbing elements. Each cribbing element has spaced upper and lower surfaces wherein substantially the entire upper and lower surface of each cribbing element is a bearing surface for transmitting a substantially vertical load to a vertically adjacent cribbing element of one stack. Each cribbing element is interconnected with at least one cribbing element of an adjacent side. The connection between interconnected cribbing elements is formed by a slot extending through one of the interconnected cribbing elements in the direction of the column and a matching projection on at least the other interconnected cribbing elements, with each projection extending in the direction of the column for the height of the cribbing element.
In one embodiment of the present invention, at least two sets of cribbing elements are provided. Each cribbing element of a first set includes a plurality of interconnecting slots and each cribbing element of a second set includes a plurality of matching projections which interconnect with the slots of the first set of cribbing elements. The cribbing elements of the second set may include a pair of matched projections with one projection at each longitudinal end of the cribbing elements. Each slot of the first set can be formed as a T-shaped slot extending the entire height of the cribbing element. The width of the T-shaped slot may be substantially equal to the width of a cribbing element.
The column cribbing system of the present invention provides that the cribbing elements of the stack of one side of the column are offset from the cribbing elements of two adjacent sides of the column. An offset between the sides provides that each cribbing element is interconnected with at least two cribbing elements of each adjacent side of the column. The cribbing elements according to the present invention are specifically designed to be formed from rectangular wooden members.
These and other advantages of the present invention will be clarified in the description of the preferred embodiments taken together with the attached figures wherein like reference numerals represent like elements throughout.
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Marianski Andrew J.
Marianski James E.
American Commercial Inc.
Pezzuto Robert E.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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