a conventional bracket left click on the image below to enlarge
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I, John PINK, am a miner who gained 20 years experience working in underground collieries in the Illawarra region*. At West Cliff Colliery, about half-way through this period, I witnessed the difficult, back-breaking work of securing overhead pipelines from elementary-design brackets (see alongside). These elementary-design brackets were attached to the rockbolts** after the rockbolts had been installed (to support the roof of a tunnel/underground roadway). The sketch alongside shows a one of these elementary-design brackets (a twin keyhole ANGLE BRACKET).
To support the pipeline a chain was locked in one key-hole aperture and then the other end, of this chain, was slung underneath the pipeline to be supported and locked in the other key-hole aperture. One of the problems with this simplistic design of bracket was that it could only support one pipeline. Another problem was that these brackets did not support the pipeline in a fixed manner as the 32mm punchout was sloppy on the 24mm rockbolt thread. To overcome the problem of only being able to support one pipeline an extra flange (with a pair of keyhole apertures) was added to the twin keyhole ANGLE BRACKET to make the bracket a "U" shape and this bracket was called an MENEGASSO BRACKET - after its initial manufacturer. The MENEGASSO BRACKET could thus support two pipelines! |
Sometimes four pipelines needed to be supported in an underground roadway, in the neatest possible array, whilst also maintaining as much head clearance as possible. I developed the Winged Keel bracket , shown alongside, to satisfy these criteria. The large-span (970mm wide) bracket, installed using a single roofbolt**, was designed for GORDONSTONE Colliery in central Queensland to support the compressed air, fresh water, pumpout and gas drainage services.
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left click on the image above to enlarge Winged Keel bracket 970 (the first underground
mining bracket to) |
The range of brackets developed were called.
FACE
EMPLACED Services Support devices
.as
they were designed to be installed when the initial roof support was
being conducted at the coal face. These brackets therefore needed
to be easily-handled to facilitate integation into this process.
Manufacturing these brackets from very high strength steel
(Bisalloy 80), reduced
the cross-section of the plate which was used in their construction,
achieving a 40% weight saving! FACE EMPLACED
Brackets also satisfied the criteria of low cost, efficient and safe
support of these pipelines,.
etc.
. |
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left click on the image above to enlarge Longwall Bracket (LW 490) (490mm wide and capable
of supporting a) |
The sketch alongside shows a roadway in an underground coal mine, in vertical cross-section. The overhead rock is held together (reinforced) with roofbolts/rockbolts*** and this composite beam is supported by the coal pillars (diagonal stroked) on either side.
The Longwall Bracket, another. FACE EMPLACED Services Support device , is shown in the upper right-hand corner of the underground roadway. |
This Longwall Bracket
(above) supports a large-bore gas drainage pipeline (yellow marked)
neatly against the roof and coal rib in an out-of-the-way manner as
possible - again from a single roofbolt! As this bracket, as with
all FACE EMPLACED Brackets, is included in the roofbolt assembly - a
saving of about 150mm in head clearance is realised! |
The main novelty of the
invention is the using of the opportunity of roofbolt installation,
necessary to support the region excavated in the desired roadway direction,
to install these FACE EMPLACED Services Support devices.
Previously these two processes, supporting of the roof and supporting
of services, were conducted separately! .
The
advantages realised by the combination of the two processes are numberous!
.. |
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To exemplify the contrast between the FACE EMPLACED Services Support invention and what preceded in the underground mining and tunnelling industries you are referred to the drawing alongside. The bracket (numbered 22 in the drawing) could be the bracket called the "twin keyhole ANGLE BRACKET", shown in the uppermost drawing on this web-page, with a slight modification of a thin strip of metal (#24) bent sufficiently to engage the "W" strap (#23) for easy installation. In this instance the "twin keyhole ANGLE BRACKET" is included in the roofbolt assembly and so the METHOD CLAIM of combining the two processes, roof support and services support, is satisfied and therefore this is an example of the FACE EMPLACED Services Support invention. If, however, the bracket had been installed AFTER the roofbolt had been installed, by placing it over the exposed thread of the roofbolt and then winding a nut up underneath, then this instance is NOT the invention - and about 150mm in head clearance is sacrificed!
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left click on the image above to enlarge then left click again Roofbolt/Bracket Assembly |
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To complete the. FACE EMPLACED Services Support device .range as far as brackets are concerned, a bracket capable of supporting main mine belt conveyors, was developed. The thickness of the Bisalloy 80 plate was increased from 5mm to 8mm to add the required strength to support the additional load(s). Again this bracket was designed for GORDONSTONE^ Colliery - for their very high-tonnage, main mine conveyor. |
left click on the image above to enlarge Combination Bracket 420 (acting as a locking
point for linked chains which) |
The sketch alongside shows a roadway in an underground coal mine, in vertical cross-section, with a set of main mine belt conveyor structure installed. Also supported from the brackets are the piped services which would be commonly in this heading. The lower portions of roofbolts are shown in the roof, over which the FACE EMPLACED Services Support brackets are placed, before the whole assembly is installed into the overhead rock. |
| Later MESH PLATES were developed to accomodate a new form of roof support - mesh modules#. Basically these FACE EMPLACED Services Support devices were designed to integrate with this new form of roof support. The FACE EMPLACED support device was held to the mesh module using a substantial hook (#24) such as the one shown in the Roofbolt/Bracket Assembly above. The mesh module is then bolted to the roof in the normal manner with at least one roofbolt passing through the nearly-horizontal section of the MESH PLATE.
It was discovered that 2mm thick steel plate was of sufficient strength to support up to 150mm bore pipelines, with two MESH PLATES used to support each approximately 6 metre long pipeline length - with a factor of safety above six. As most piped services in panels do not exceed 150mm in diameter MESH PLATES therefore became the dominant form of services support. |