U.S. patent number 4,601,616 [Application Number 06/711,303] was granted by the patent office on 1986-07-22 for roof support system for a mine and the method and tooling for providing the same.
This patent grant is currently assigned to Jennmar Corporation. Invention is credited to Ken Barish, Paul Yacisin.
United States Patent |
4,601,616 |
Barish , et al. |
July 22, 1986 |
Roof support system for a mine and the method and tooling for
providing the same
Abstract
An improved roof support system for a mine or the like is of the
type which includes a pair of plates secured to the roof of the
mine at opposite sides thereof adjacent opposing ribs of the mine
and a horizontal, transverse reinforcing member extending between
the pair of plates. The improvement includes the reinforcing member
having a first rod with a first end thereof secured to a first of
the plates and a second end extending toward the second plate. The
second plate includes a vertical portion with a transversely
extending opening therethrough. The reinforcing member also
includes a second rod in the form of a bolt which has a bolt head
located against the vertical portion of the second plate with the
threaded second end thereof extending through the opening toward
the first plate. The second end of the first rod includes a sleeve
mounted thereon having a threaded bore therethrough for receipt of
the threaded end of the bolt. The bolt and the first rod are
coupled together by insertion of the threaded end of the bolt into
the threaded bore to form the reinforcing member. The reinforcing
member is capable of producing tension between the first and second
plate which tension may be varied by rotation of the bolt head of
the bolt relative to the first rod. The invention also includes the
method of supporting the roof of a mine and a tool for providing
the same.
Inventors: |
Barish; Ken (Indiana, PA),
Yacisin; Paul (Patton, PA) |
Assignee: |
Jennmar Corporation
(Pittsburgh, PA)
|
Family
ID: |
24857536 |
Appl.
No.: |
06/711,303 |
Filed: |
March 13, 1985 |
Current U.S.
Class: |
405/288;
405/259.1; 405/302.2 |
Current CPC
Class: |
E21D
11/006 (20130101) |
Current International
Class: |
E21D
11/00 (20060101); E21D 020/00 (); E21D
021/00 () |
Field of
Search: |
;405/259,260,261,262,258,303 ;81/57.11,55,57.13,57.14 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Mine Controls Bad Roof with Trusses Bolted on Cycle, by Ken Barish,
Coal Age 5/85, pp. 62-66. .
Current Trends in Roof Truss Hardware, by C. P. Manglesdorf. .
Hydraulic Tensioning of a Birmingham Roof Truss, by C. W.
Bollier..
|
Primary Examiner: Taylor; Dennis L.
Attorney, Agent or Firm: Price, Jr.; Stanley J.
Claims
We claim:
1. An improved roof support system for a mine or the like of the
type which includes a pair of plates secured to a roof of said mine
at opposite sides thereof adjacent opposing ribs of said mine and a
horizontal, transverse reinforcing member extending between said
pair of said plates, said improvement comprising:
said reinforcing member including a first rod means having a first
end secured to a first of said pair of said plates and a second end
extending toward a second of said pair of said plates;
said second plate having a vertical portion thereof with a
transversely extending opening therethrough;
said reinforcing member including a second rod means having a first
end with an integral enlarged head portion with torque applying
surfaces thereon, said first end being located in abutting relation
with said vertical portion of said second plate with said second
rod means extending through said opening with a second end thereof
extending toward said first plate; and
said second ends of said first and said second rod means including
mating threaded means thereon for coupling said first and said
second rod means together to form said reinforcing member which is
capable of producing tension between said first and said second
plates so that said tension may be varied by rotation of said
enlarged head of said second rod means relative to said first rod
means.
2. The improved roof support system as set forth in claim 1,
wherein said second plate is secured to said roof with said
vertical portion thereof a predetermined distance from an adjacent
rib of said mine, said predetermined distance being significantly
less than a horizontal distance between said first and said second
plates,
said second rod means having an overall length less than said
predetermined distance whereby said second rod means can be
installed in said transversely extending opening of said vertical
portion of said second plate when said second plate is secured to
said roof.
3. The improved roof support system as set forth in claim 1,
wherein said first rod means includes means for preventing relative
rotation between said first rod means and said first plate when
tension is being produced between said first and said second
plates.
4. The improved roof support system as set forth in claim 3,
wherein said means for preventing relative rotation includes
frictional contact between said first end of said first rod means
and said first plate.
5. The improved roof support system as set forth in claim 1,
wherein said first plate has a vertical portion thereof with a
transversely extending opening therethrough.
6. The improved roof support system as set forth in claim 5,
wherein said first and said second plates are of substantially the
same configuration.
7. The improved roof support system as set forth in claim 5,
wherein said first rod means includes an elongated rod with
threaded regions at the opposite ends thereof, said first end of
said first rod means includes a nut threadably secured on one of
said threaded regions of said rod as said rod extends through said
opening in said vertical portion of said first plate, and said
second end of said first rod means includes a sleeve member with a
longitudinally extending threaded bore therethrough, said sleeve
being threadedly secured to the other of said threaded regions of
said rod.
8. The improved roof support system as set forth in claim 7,
wherein said second rod means includes a bolt having a head thereon
at said first end thereof and a threaded region at said second end
thereof, said threaded region of said second rod means threadedly
secured in said threaded bore of said sleeve.
9. A method of supporting a roof of a mine or the like comprising
the steps of;
securing a pair of roof supporting plates at opposite sides of said
roof adjacent opposing ribs of said mine, each of said plates
having a vertically extending force bearing surface thereon;
providing a first rod means having securing means at a first end
thereof and a threaded coupling at a second end thereof;
providing a second rod means having an enlarged integral head
portion with torque applying surfaces thereon at a first end
thereof and a threaded region at a second end thereof which is
capable of being threadably mated with said threaded coupling of
said first rod means;
installing said first rod means with said securing means of said
first end against said force bearing surface of a first of said
pair of said plates and said second end extending toward a second
of said pair of said plates;
installing said second rod means with said enlarged head portion
against said force bearng surface of said second plate;
threadedly engaging said second rod means to said threaded coupling
on said first rod means; and
producing tension between said first and said second plates by
rotating said enlarged head portion of said second rod means
relative to said first rod means to move said threaded region of
said second end of said second rod means longitudinally into said
threaded coupling of said first rod means.
10. The method as set forth in claim 9, wherein said step of
producing tension between said first and said second plates is
accomplished by rotating said head portion of said second rod means
while said first rod means is prevented from rotation relative to
said first plate.
11. The method as set forth in claim 9, wherein said step of
providing tension between said first plate and said second plate
produces frictional contact between said securing means of said
first rod means and said force bearing surface of said first plate
to prevent relative rotation therebetween.
12. The method as set forth in claim 9, wherein said first plate
includes a transversely extending opening in said force bearing
surface, said securing means includes a threaded end and a nut
threaded thereon, and said step of installing said first rod means
includes extending said threaded end through said opening of said
first plate and installing said nut thereon between said adjacent
rib and said force bearing surface of said first plate.
13. The method as set forth in claim 9, wherein said second plate
includes a transversely extending opening in said force bearing
surface and said step of installing said second rod means includes
inserting said threaded region of said second end through said
opening between said adjacent rib and said forced bearing surface
until said enlarged integral head portion is located against said
force bearing surface.
14. The method as set forth in claim 1, wherein said enlarged head
portion includes an integral bolt head and washer with said washer
being installed between said bolt head and said force bearing
surface during the installing of said second rod means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved roof support system for a
mine or the like, and more specifically, to such a roof support
system which utilizes a horizontal, transverse reinforcing member
which is simple to provide and conveniently utilized to produce a
desired tension between a pair of roof plates of the roof support
system.
2. Description of the Prior Art
Although there are numerous methods for supporting the roof of
mines, openings, or the like, one type which is commonly employed
includes a roof truss structure which generally includes two
inclined cords and a horizontal cord. The inclined cords are
usually mine roof bolts or the like which extend into holes in the
mine roof at about a 45.degree. angle. The mine roof bolts may be
anchored in the inclined holes in the roof by well known means such
as expansion shells and/or resin bonding. The horizontal cord or
tie member extends transversely across the roof the mine between
the terminal ends of the inclined cords located at the surface of
the roof. Providing means for applying tension to the anchored,
inclined cords and the horizontal cords can result in sufficient
upward force being generated on the roof to allow safe operation in
the mine or the like while preventing uncontrolled vertical
downward movement of the roof or any other creeping movement
thereof which might cause it to become unstable.
U.S. Pat. No. 2,667,037 disclosed a general roof support system
which basically provides the type of upward forces described
hereinabove. Specifically, a horizontal beam or the like was
positioned transversely of the mine opening across the roof and was
retained in place by a plurality of inclined bolts which anchored
the horizontal beam and provided overall integrity for roof
support.
U.S. Pat. No. 3,427,811 disclosed a system which provided for the
same type of upward forces to support a mine roof but included the
additional feature of a means for varying the tension on the
horizontal cord and reportedly resulted in an overall system which
exerted at least approximately equal tension on the horizontal cord
and the inclined anchoring cords. Although U.S. Pat. No. 3,505,824,
and 3,509,726 disclose roof support trusses or systems which
function generally like that mentioned hereinabove, they employ
different elements to create a combined tension on the inclined
cord and horizontal cord components.
The roof support system generally disclosed in U.S. Pat. No.
4,395,161 results in a similar configuration but includes features
for ease of installation and adjustability which may exist in the
prior art devices mentioned hereinabove but are not as clearly
demonstrated. Specifically, the device includes a pair of
transition plates to be installed in the roof of the mine by
inclined cords in the form of mine roof bolts which can be
separately installed and adjusted to provide the desired tension
thereto. Subsequently, the same or a different mining crew is then
capable of installing a horizontal, transversely extending
reinforcing member to provide the horizontal cord component of the
mine roof truss. In the case of U.S. Pat. No. 4,395,161, the
reinforcing member is disclosed to preferably be an elongated rod
having threaded ends with adjusting nuts installed at each of the
ends to produce tension between the transition plates.
When trying to determine which truss system or other roof support
system should be utilized, there are some mine operating conditions
and safety requirements which should be taken into consideration. A
more attractive roof support system would be one which could reduce
installation time to mining cycle time, included a means to provide
uniform truss tensioning during installation with a capability to
vary tensioning depending upon roof conditions and would improve
the overall work conditions. These objectives were founded on the
need to increase the effectiveness of the truss in roof support and
reduce the cost of roof control. It is well known that roof control
effectiveness can be enhanced by quickly supporting the roof after
coal extraction. By installing the truss in the mining cycle, the
time that the roof remains unsupported by the truss is decreased.
By tensioning uniformly, a way is open for the truss to become the
primary roof control method, thus reducing the requirement in many
cases for roof bolting and trussing in the same location.
Further, it has been found that proper truss tensioning improves
system effectiveness. Using a pipewrench as a tensioning tool has
shown considerable variability in truss tensioning during
installation and tensioning is dependent upon the size and strength
of the operator and the time of day in which the truss is
installed. For example, early in a work shift, trusses are usually
installed with proper tensioning, but as the day wears on the
quality of workmanship declines as in many other industries.
Truss tensioning is an unpopular task because conditions in some
mining areas create an unnatural strenuous working position for the
individual actually tensioning the truss. To gain a greater
acceptance of this operation, any improvement in such a system
which could reduce the installation time, reduce the strenuous
nature of the work and eliminate the potential for straintype of
injuries would be desirable.
Accordingly, while the device shown in U.S. Pat. No. 4,395,161
incorporates separate installation of a roof plate with a
separately adjustable inclined mine roof bolt, any improvement to
the horizontal, transversely extending reinforcing member would be
desirable. Further, it would clearly be an advantage if a more
simplified means were available for installing such a horizontal,
transverse reinforcing member which method also facilitated the use
of power tools for creating the desired tension between the roof
plates.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an
improved roof support system for a mine or the like of the type
which includes a pair of plates secured to a roof of the mine at
opposite sides thereof adjacent opposing ribs of the mine and a
horizontal, transverse reinforcing member extending between the
pair of plates. The improvement includes the reinforcing member
including a first rod means having a first end secured to a first
of the pair of plates and a second end extending toward a second of
the pair of plates. The second plate has a vertical portion thereof
with a transversely extending opening therethrough. The reinforcing
member includes a second rod means having a first end including an
enlarged head with a torque applying surface thereon. The first end
is located against the vertical portion of the second plate as the
second rod means extends through the opening with a second end
thereof extending toward the first plate. The second ends of the
first and the second rod means includes mating threaded means
thereon for coupling the first and the second rod means together to
form the reinforcing member which is capable of producing tension
between the first and second plates which tension may be varied by
rotation of the enlarged head of the second rod means relative to
the first rod means.
Further in accordance with the present invention there is provided
a method of supporting a roof of a mine of the like including the
initial step of securing a pair of roof supporting plates at
opposite sides of the roof adjacent opposing ribs of the mine. Each
of the plates has a vertically extending force bearing surface
thereon. A first rod means having securing means at the first end
thereof and a threaded coupling at a second end thereof is
provided. There is provided a second rod means having an enlarged
head portion with torque applying surfaces thereon at a first end
thereof and a threaded region at a second end thereof which is
capable of being threadably mated with the threaded coupling of the
first rod means. The first rod means is installed with the securing
means of the first end against the force bearing surface of a first
of the pair of plates and a second end extending toward a second of
the pair of plates. The second rod means is installed with the
enlarged head portion against the force bearing surface of the
second plate as the threaded region of the second end thereof is
threadably engaged with the threaded coupling of the first rod
means. Tension is produced between the first and the second plates
by rotating the enlarged head portion of the second rod means
relative to the first rod means to increase the engagement of the
threaded region of the second end of the second rod means with the
threaded coupling of the first rod means.
Still further in accordance with the present invention there is
provided a tool for producing tension between a pair of plates
secured to a roof of a mine or the like. The pair of plates are
located at opposite sides of the roof adjacent opposing ribs of the
mine and have a horizontal, transverse reinforcing member extending
therebetween. The reinforcing member has a first end and a second
end threadably joined to allow relative rotation therebetween to
vary an overall length of the reinforcing member. The first end is
nonrotatably secured to the first of a pair of the plates and the
second end includes an enlarged head abutting a force bearing
surface of the second of a pair of the plates on a side thereof
toward a rib of the mine adjacent the second plate. The tool
includes a source of power an means for converting the source of
power to a rotating, torque applying output element. An output
fitting on the torque applying output element is capable of mating
with the enlarged head of the second end of the reinforcing member
to produce rotation thereof. A stablizing means extends between the
means for converting and the second plate to prevent relative
rotation thereof during rotation of the enlarged head by the output
fitting of the output element.
Consequently, it is a primary object of the invention to provide an
improved roof support system which is relatively inexpensive to
provide and can be simply and conveniently installed and
adjusted.
It is another object to provide a method for installing such an
improved roof support system.
Still another object of the invention is to provide a tool which
can be readily employed with such an improved roof support system
which will reduce the time required for installing a horizontal,
transverse reinforcing member and provide better control for the
eventual tension supplied thereby between a pair of roof
plates.
These and other objects of the present invention will be more
completely disclosed and described in the following specification,
the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view of a section of a mine or the like
including a preferred embodiment of an improved roof support system
of the present invention.
FIG. 2 is an exploded view of the major components of the preferred
embodiment as shown in FIG. 1.
FIG. 3 is a view like that shown in FIG. 1 as the horizontal,
transverse reinforcing member of the preferred embodiment as it is
being installed.
FIG. 4 is a view as shown in FIG. 3 with the horizontal, transverse
reinforcing member partially installed.
FIG. 5 is a view like that shown in FIG. 4 with the horizontal,
transverse reinforcing member in position for final tensioning.
FIG. 6 is a view of the preferred embodiment as seen in FIG. 5 with
a preferred tool for providing tension to the roof support system
demonstrating its position when tension is being created.
FIG. 7 is an exploded, perspective view of the preferred tool of
the invention showing its relationship with other components of the
preferred improved roof support system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As seen in FIG. 1, a typical mine shaft or opening 10 would include
a roof 12 between opposing ribs 14, 16. An improved roof support
system 18 includes various features of the invention and is of the
type which includes a pair of plates 20, 22 which are secured to
the roof 12 by inclined cords in the form of roof bolts 24. The
roof bolts 24 are installed through bores 26 in a conventional
manner with associated anchoring devices 28 being fully installed
at the terminal end of each bore 26 to retain the bolt 24 therein
and allow tension to be created thereby. It will be seen that any
number of such anchoring means could be employed without affecting
the specific features of the improvement represented by the present
invention. For example, the roof bolts may utilize mechanical,
resin or a combination of mechanical and resin bonding to insure
proper support of the plates 20, 22 while allowing proper tension
to be applied thereto to produce the overall desire resulting
forces on the roof 12.
A horizontal, transverse reinforcing member 30 extends between the
plates 20, 22. The preferred reinforcing member 30 includes a first
rod means 32 having a first end 34 secured to the plate 20 and a
second end 36 extending toward the plate 22. The preferred plate 22
includes a vertically depending portion 38 thereof which has a
transversely extending opening 40 therethrough. Reinforcing members
41 may be provided at each side of the vertically depending portion
38 to provide overall strength to each of the plates 20, 22 even
though only one such member 41 may be shown in some of the Figures
to simplify the drawings. The reinforcing member 30 also includes a
second rod means 42 which has a first end 44 including an enlarged
head 46, preferably in the form of a bolt head with torque applying
surfaces thereon. The first end 44 is located against the vertical
portion 38 of the plate 22 as the second rod means 42 extends
through the opening 40 with a second end 48 thereof extending
toward the plate 20.
Although the particular components provided could be altered while
still being within the scope of the invention, it should initially
be recognized that the second end 36 of the first rod 32 and the
second end 48 of the second rod 42 should include mating threaded
means thereon for coupling the first rod means 32 and second rod
means 42 together to form the preferred reinforcing member 30. When
so threaded for coupling, the reinforcing member 30 will be capable
of producing tension between the plates 20 and 22 which tension may
be varied by rotating the enlarged head 46 of the second rod means
42 relative to the first rod means 32. As seen in FIGS. 2 through
5, there are various components of the preferred reinforcing member
30 which are simple to provide and install and are easily adaptable
for roof support systems in different locations requiring different
transverse distances between the plates 20, 22.
Accordingly, when a plurality of the plates 20, 22 are installed
for a series of roof support systems, the overall length of the
desired reinforcing members 30 can be determined. Although other
configurations could be employed in the preferred reinforcing
member 30, it is desirable for the first rod member 32 to be longer
and extend across the primary length between the plates 20, 22 and
a shorter second rod member 42 to be employed. As a result, the
first rod member 32 can include a primary rod portion 50 which is
either integrally formed or made to a predetermined length by a
coupling element 52 centrally mounted therein. More significantly,
the primary rod portion 50 will in the preferred first rod means 32
include a first threaded end 54 and a second threaded end 56. The
threaded end 54 will be joined to the plate 20 through a similar
hole 40 in a vertical portion 38 by retaining a nut means 58. The
preferred nut means 58 may include two nuts in order to insure that
they are properly locked in position on the threaded end 54. The
second end 36 of the first rod means 32 will preferably include a
sleeve coupling 60 which has a longitudinally extending threaded
bore 62 therethrough. The sleeve coupling 60 is partially mounted
on the threaded end 56 of the primary rod portion 50 while insuring
that a portion of the threaded bore 62 extends outwardly
therefrom.
The shorter, preferred second rod means 42 is a bolt having a bolt
head 46 thereon which can be utilized in conjunction with a washer
64. The second end 48 of the bolt 42 is threaded to mate with the
threaded bore 62 of the sleeve coupling 60 of the first rod means
32.
As thus described, it should be clear that a mining crew would be
capable of providing a series of reinforcing members 30 by
utilizing a bundle of first rod means 32 which are preassembled the
proper length and a second bundle of bolts which would be employed
as the second rod means 42.
As seen in FIG. 3, after the plates 20, 22 are fully installed, the
first rod means 32 can be installed by extending the threaded end
54 through the hole 40 of plate 20 and installing the nut means 58.
Installed in this manner, the sleeve coupling 60 would extend
toward the plate 22. The second rod means 42 in the preferred form
of a bolt is installed with the head 46 and washer 64 of the bolt
against a force bearing surface 66 of the vertical portion 38 of
the plate 22 with the threaded end 48 capable of being threadably
engaged with and received within the threaded bore 62 of the sleeve
coupling 60 of the first rod means 32. However, as seen in FIG. 3,
it should be noted that in most installations of this type, the
plates 20, 22 are secured to the roof 12 with the force bearing
surface 66 of the vertical portion 38 thereof a predetermined
distance D from the adjacent corresponding rib 14, 16 of the mine.
The predetermined distance D is significantly less than a
horizontal distance H between the plates 20, 22. Accordingly,
since, as it will be seen later, it is desirable for the second rod
means 42 to have an integrally formed enlarged head 46 thereon, the
overall length L of the second rod means 42 should be less than the
predetermined distance D to allow for easy installation of the
second rod means 42 in the transveresly extending opening 40 as it
is positioned between the force bearing surface 66 and the adjacent
rib 16. Although there may be some alternative configurations for
providing horizontal, transverse reinforcing members which employ
first rod means and second rod means which are approximately the
same overall length, it can be seen that the preferred
configuration in the form of first rod means 32 as described
hereinabove and second rod means 42 as described hereinabove can be
conveniently employed to produce a horizontal reinforcing member 30
which extends across plates 20, 22 with varying horizontal
distances H therebetween but is simple to assemble and install.
Referring to FIG. 4, with both the first rod means 32 and the
second rod means 42 installed as described hereinabove, the second
rod means 32 can be threadably installed by hand within the
preferred sleeve coupling 60. As seen in FIG. 5, this hand
installation can continue to produce insertion of the threaded end
48 into the threaded bore 62 until the enlarged head 46 is brought
into contact with the force bearing surface 66 of the plate 22. At
the same time, the nut means 58 of the first rod means 32 will be
brought into contact with the force bearing surface 66 on the plate
20. With the preferred reinforcing member 30 initially installed in
this manner, it has been found that frictional forces created
between the nut means 58 and the force bearing surface 66 of the
plate 20 will be sufficient to allow further, forced rotation of
the enlarged head 46 to produce relative rotation between the first
rod means 32 and the second rod means 42 while the first rod means
32 remains stationary without any rotation relative to the plate 20
to which it is secured.
Although the preferred improved roof support system 18 as described
for initial installation may appear to be similiar to the prior art
devices as disclosed in the patents mentioned hereinabove, there
are features associated therewith for providing tension on the
plates 20, 22 in a more convenient and effective manner.
Specifically, while the prior devices as discussed hereinabove
primary utilized either turn buckle configurations or adjusting
nuts on threaded bolt ends extending therethrough, the preferred
configuration of the improved roof support system 18 employs an
enlarged head 46 which remains located against a predetermined
force bearing surface 66 throughout adjustment to produce the
desired tension on the plates 20, 22. Since the head 46 is portions
of the second rod means 42, there is no bolt end or rod section
located near the working surfaces which has heretofore interferred
with and complicated efforts to provide a means for power torquing
the reinforcing member.
As seen in FIGS. 6 and 7, the preferred means for power torquing
the reinforcing member 30 and creating desired tension between the
plates 20, 22 is a preferred tool 70. Such a tool 70 must include a
source of power and a means for converting this source of power to
a rotating torque applying element. It has been found that
presurized hydraulic fluid can provide such a source of power and a
hydraulic motor can be utilized as a means for converting the
source of power to the proper output. In the preferred tool 70 a
hydraulic drill 72 is joined to a speed reducing, force multiplier
74 to provide the output shaft with an output fitting 76 thereon.
The output fitting 76 can include a conventional socket fitting
designed to mate with the conventional bolt head which is utilized
in the preferred second rod means 42.
However, because of the forces required for properly applying
sufficient torque to generate the desired tension between the
plates 20, 22, a means must be provided for stabilizing the
hydraulic drill 72 and force multiplier 74 to prevent relative
rotation thereof with respect to the plate 22 during rotation of
the bolt head by the socket fitting. In the preferred tool 70, this
is provided by a stabilizing means 78 including a bracket 80 which
extends between the force multiplier 74 and plate 22. The preferred
bracket 80 includes first abutting elements 82 at one end thereof
to make abutting contact with the plate 22 and second abutting
elements 84 at the other end thereof to make abutting contact with
the force multiplier 74. Although any number of configurations
could be employed to accomplish such a feature, the preferred
bracket 80 has first abutting elements 82 in the form of a pair of
rods 86 which extend through corresponding holes 88 in the vertical
portion 38 of the plate 22. The second abutting elements 84 include
the sides 90 of a notch 92 which receives a major body portion of
the force multiplier 74 therein when the tool 70 is being employed
to produce rotation of the enlarged head 46.
It has been found, for example, that a torque of about 200 foot
pounds can be applied to an enlarged head 46 to produce the desired
tension between typical plates 20, 22. In one configuration, the
force multiplier 74 will reduce the speed while multiplying the
output force therefrom at a ratio of about three to one.
Accordingly, it has been found that a hydraulic drill 72 can be
preset to operate at a maximum output force of about 60 to 70 foot
pounds to produce the desired torque needed to insure proper
tension between the plates 20, 22. Such a configuration allows for
rapid, automatic torsion to be applied to the reinforcing member 30
insuring that the desired tension between plates 20, 22 is provided
during initial installation of the preferred roof support system
18.
It should be recognized that alterations could be made to the
preferred embodiment as described hereinabove without departing
from the spirit of the invention as claimed. Specifically, although
it is preferred for plates 20, 22 to be of the same design for ease
of installation and inventory purposes, one or the other could be
altered to specifically accommodate a different form of first rod
means or second rod means while still being within the scope of the
invention. Similarly, although the use of inclined cords to secure
the plates 20, 22 is taught and would primary be employed, it
should be recognized that there may be other types of roof support
systems which employ such plates and utilize a tension applying
reinforcing member therebetween which such reinforcing member could
fall within the scope of the present invention. Still further,
although the preferred tool for producing the desired tension on
the roof support plates is taught herein, any number of any other
types of tools as defined in the claims could be employed.
* * * * *