BACKGROUND OF THE INVENTION Since the development of the mine roof support crib described in patent number 5,746,547, market experience has shown that, mine opening conditions exist in which the support generated by this design is more than what is required for stability. For example, empirical testing has proven that for stability reasons a 27"long product is required at heights of eight feet. The conventional product produced under Patent'547 at 27"of length produces strengths of a conventional nine point crib. In some applications, this is more strength than the conditions require. However, a conventional four pointer crib or timber post would be insufficient. It would be advantageous therefore to have a support design intermediate in strength between these technologies.

SUMMARY OF THE INVENTION The present invention pertains to a mine roof support crib. The crib comprises a plurality of chocks that are connected together through notches in the chocks to form a triangular structure having three external sides.

Preferably, the chocks on each side interlock such that there

is substantially 100% surface contact between the horizontal surfaces of adjoining layers.

The present invention pertains to a method of forming a mine roof support crib. The method comprises the steps of placing a first chock having a plurality of notches in a mine. Then there is the step of linking a second chock having a plurality of notches with the first chock to a first notch of the plurality of notches of the first chock. Next there is the step of linking a third chock having a plurality of notches with a first notch of the plurality of notches of the second chock and a second chock of the plurality of notches of the first notch. Then there is the step of linking a desired number of additional chocks onto each other or the first, second or third chocks through notches of the respective chocks until a triangular structure having three external sides is formed to provide support of a mine roof.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which: Figures la-ld are schematic representations of 3D, side, top and top view stacked, respectively, of an embodiment of a crib having a triangular structure.

Figure 2 is a schematic representation of a preferred embodiment of a crib having a triangular structure.

Figure 3 is a schematic representation of an overhead view of a crib having a triangular structure.

Figures 4a-4d are schematic representations of 3D, side, top and stacking view, respectively, of a chock having two notches.

Figures 5a-5d are schematic representations of 3D, side, top and stacking view, respectively, of a chock having three notches.

Figures 6a-6d are schematic representations of 3D, side, top and stacking view, respectively, of a chock having four notches.

Figures 7a-7d are schematic representations of side views and stacking view, respectively, of an end piece.

Figures 8a-8d are schematic representations of a 3D, side and top view, respectively, of a chock having four notches.

DETAILED DESCRIPTION Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to figure 2 thereof, there is shown a mine roof support crib 10. The crib 10 comprises a plurality of chocks 12 that are connected together through notches 14 in the chocks 12 to form a triangular structure having three external sides 16.

Preferably, the chocks on each side interlock such that there is substantially 100% surface contact between the horizontal surfaces of adjoining layers. Preferably, each

chock has a long axis 18 and each notch of the chock is cut at a right angle to the long axis 18 of the chock.

The width of each notch preferably has a minimum dimension of Minimum notch width = (chock width/sine theta) + (chock width/tangent theta) where theta = (N-2/N) 180 degrees and N equals the number of sides 16. Preferably, each chock has a plurality of notches 14 and the sum of the depth of the notches 14 in each chock is substantially equal to the rise h of the chocks 12.

At least one of the chocks 12 preferably has two notches 14 of different depths, wherein the difference in the depth of the notches 14 is the rise of the chocks 12 divided by the number of sides 16 N of the structure. Preferably, at least one of the chocks 12 has three notches 14 of equal depth and the depth of each notch = the rise of the chock divided by the number of sides 16. At least one of the chocks 12 preferably has four notches 14 of equal depth and the depth of each notch = 1/4 the rise of the chock.

Preferably, at least one of the chocks 12 has four notches 14 of varying depth, with the notches 14 on one surface of the chock having equal depths and the notches 14 on the opposite surface to the one surface having unequal depths with the notches 14 on the opposite service having a difference in depth equal to the rise of the chock divided by the number of sides 16 of the structure.

The structure preferably includes base end and top end pieces 30 which provide a level and stable base and top to the structure.

Preferably, the rise h = 6 inches, the chock width = 3.5 inches and the length of the chock = 30 inches.

The present invention pertains to a method of forming a mine roof support crib 10. The method comprises the steps of placing a first chock having a plurality of notches 14 in a mine. Then there is the step of linking a second chock having a plurality of notches 14 with the first chock to a first notch of the plurality of notches of the first chock. Next there is the step of linking a third chock having a plurality of notches with a first notch of the plurality of notches of the second chock and a second chock of the plurality of notches of the first notch. Then there is the step of linking a desired number of additional chocks onto each other or the first, second or third chocks 12 through notches 14 of the respective chocks 12 until a triangular structure having three external sides 16 is formed to provide support of a mine roof.

Preferably, each chock has a long axis 18 and each notch of the chock is cut at a right angle to the long axis 18 of the chock.

The width of each notch preferably has a minimum dimension of Minimum notch width = (chock width/sine theta) + (chock width/tangent theta)

where theta = (N-2/N) 180 degrees and N equals the number of sides 16.

Preferably, before the placing step, there is the step of placing a base end piece 30 on the mine floor to provide a level and stable base to the structure. After the linking a desired number of additional chocks 12 step, there is preferably the step of placing a top end piece 30 on the top of the structure to complete the top of the structure.

What is disclosed is: A mine roof support crib 10 constructed of chocks 12 with notches 14 cut at right angles to the long axis 18 of the chock and with a width sufficient to accommodate the building of a structure with three or more sides 16. The chocks 12 used in building this structure can have 2,3 or 4 notches 14 and these notches 14 may have various depths depending on the structure to be built. The key elements of the design are as follows.

1. Each notch is cut at a right angle to the long axis 18 of the chock. The width of each notch to be a minimum dimension as determined by Formula #1 (see Figure 3).

2. The chocks 12 have a plurality of notches 14 and the sum of the depth of the notches 14 in each chock is substantially equal to the rise of the chock.

3. When two notches 14 of different depths are used, the difference in the depth of the notches 14 must be the rise of the chock divided by the number of sides 16 the structure to be built will have (defined as n on Figure 3).

4. When three notches 14 are used, all notch depths will be equal and the depth of each notch will be the rise of the chock divided by the number of sides 16.

5. When four notches 14 of equal depth are used the depth of each will be 1/4 the rise of the chock.

6. When four notches 14 of varying depths are used, the notches 14 on one surface of the chock will have equal depths and the notches 14 on the opposite surface will have unequal depths. The notches 14 on this opposite surface will have a difference in depth equal to the rise of the chock divided by the number of sides 16 of the structure to be built.

7. For completion of each structure particular"end"pieces will be required to provide a level and stable base to the structure and to complete the upper surface of the structure to the mine roof.

Example in a triangular structure: For a triangular structure to be built with chocks 12 of dimensions: Rise = 6" Width = 3.5" Length = 30" A. The notch width will be determined as shown. (Formula #1 on Figure 3) B. When chocks 12 with two notches 14 are used in the construction of a triangular structure, the difference in the depth of the notches 14 will be 1/3 the rise of

the chock. (Figures 4a-4d). End pieces 30 will be as shown. (Figure 4). The chocks 12 will be stacked as shown. (Figure 4). As an alternate stacking arrangement, two chocks 12 are stacked with the notches 14 up and the third with the notches 14 pointed downward as shown in Figure 4b. The upper and lower surfaces of all chocks 12 will be parallel to each other AND to the mine floor and roof.

C. When chocks 12 with three notches 14 are used and all notch depths are the same, all notch depths will be 1/3 the rise of the chock. (Figures 5a-5d). End pieces 30 will be as shown. (Figures 5a-5d). The chocks 12 will be stacked as shown. (Figures 5a-5d). As in the two notch design, there is a similar alternate stacking arrangement with two"up"and one"down". Also, the upper and lower surfaces of all chocks 12 are again parallel to each other AND to the floor and roof.

D. When chocks 12 with four equal depth notches 14 are to be used, the notch depths will be 1/4 the rise of the block. (Figures 6a-6d). One configuration of the end pieces 30 will be as shown. (Figures 7a-7d). Chocks 12 will be stacked as shown. (Figures 6a-6d). In this design, the upper and lower surfaces of chocks 12 on each face will be parallel to each other but will NOT be parallel to chocks 12 on either of the other two faces.

None of the upper or lower surfaces on any chock will be parallel to the roof or floor of the mine.

E. When chocks 12 with four notches 14 of varying depths are to be used, two of the notches 14 on opposite ends of the chock but on the same surface will have equal

depths. The two notches 14 on the opposite surface will have a difference in depth equal to 1/3 the rise of the chock. (Figures 8a-8d). End pieces 30 will be as shown.

(Figures 8a-8d). Chocks 12 will be stacked as shown. (Figures 8a-8d). As described in B&C above, there is an alternate stacking arrangement that uses the two"up" and one"down"in each layer. Also, the upper and lower surfaces of all chocks 12 are again parallel to each other AND to the floor and roof.

An alternative embodiment is a structure of chocks 12 with four, equal depth notches 14 cut at an acute angle to the long axis 18 of the chock, stacked in a fashion to create a triangular structure. (See Figures la-ld). The angled notches 14 were formed to allow stable stacking in the triangular form.

The angle notch creates complexity in manufacture and in the construction of the support.

Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.