Longwall Shearer Cable-Handling System – Overview

  • The longwall shearer cable-handling system is an integral component of longwall mining operations. It houses, protects, and controls the movement of the power cables and hoses that service the shearer of the underground longwall mining machine as it traverses the face of the mineral seam.
  • The cable-handler resembles a chain, in form and function; it consists of a series of connected links. Each individual link forms a rectangular enclosure through which the shearer’s supply cables and hoses pass (illustration above).
  • Since the supply cables and hoses are enclosed within the cable-handler, they are supported, controlled, and protected by the cable-handler. Without the cable-handler, the cables and hoses would collapse and kink when folded, become tangled, dragged, snag, and be cut due to the abrasive conditions, etc.
  • The cable-handler components require replacement frequently – an unavoidable consequence of the extremely harsh and abrasive conditions the cable-handler operates under. The cable-handler is comprised of consumable component links each intended to take the wear and abrasion that would otherwise be dealt to the valuable cables and hoses it protects. 

The Cable-Handling System – How it Works

  • In a typical cable-handler, one end of the cable-handling system is fixed to a connection point on the shearer. The other end of the cable-handler remains stationary, and is fixed at one of the ends of the longwall face, usually the main gate end.
  • When the shearer is positioned at the opposite end of the longwall face, the cable-handler is completely extended and lies in a channel along the face, until upon getting closer to the shearer, the cable-handler leaves the channel and curves up to the connection point on the shearer, typically in excess of one metre above the channel.
  • When the shearer travels towards the near end of the longwall face, the cable-handler first forms a controlled bend from the shearer connection point to the channel below. It is critical that the radius of this bend is maintained above a certain limit, damage to the cables and hoses would otherwise soon follow, and the cable-handler prevents the curve collapsing below this limit. As the shearer travels further along the face, the section of handler between the now 180° bend, and the shearer begins to dip, eventually resting on the cable-handler links below. The doubled over cable-handler slides on top of itself as the shearer continues along the face. When the shearer reaches the end, the cable-handler will have been approximately folded in half.

The CobraCo – Market / Application Opportunity

  • The CobraCo is a component which when connected with other links, creates a cable-handling system to protect the cables and hoses carrying the power, air, and water essential for the operation of mining equipment.
  • Product and market development to date has been focused on equipment involved in the following mining activities: underground longwall mining, other underground mining operations, well-head manipulation in the oil & gas industry, and submersible cable-handling (refer figure 1).
  • Design variations may also be suitable for protecting cables in high traffic zones, such as building construction sites, civil works projects, and in open-cut mining operations (refer figure 2).

The Cable-Handling System – Different Configurations 

  • There are several cable-handling systems in use, each typically of a ‘single-pull’ or a ‘twin-pull’ configuration. The ‘pull’ designation is referring to the number of independent connections between adjoining links in the cable-handler chain (figure 5).
  • A ‘twin-pull’ system is generally more robust and reliable than a ‘single-pull’ system. A level of redundancy is also inherent in the ‘twin-pull’ system ,as should a link connection fail there would still be one ‘pull’ remaining.
  • The ‘twin-pull’ cable-handling system typically comprises links made of four major components. With reference to CobraCo ‘twin-pull’ cable-handler for illustrative purposes only (figure 6) these components are:
    • Two sidewalls (aqua)
    • Two plates (red) spanning the sidewalls, and forming the top and bottom of the rectangular cable enclosure. The plates are fastened to the sidewalls at each end.
    • The link coupling elements (yellow) are incorporated into each of the sidewalls. Each sidewall, excluding those of the first and last links, is connected to the corresponding sidewalls of the preceding and following links.
    • The sidewall connections are a pin-type joint with a 316 stainless bolt (black) allowing rotation around only one axis.

The CobraCo – A Clear Customer Business Case

  • Many mining activities require effective cable-handling systems to protect the cables, and hoses carrying the power, air, and water essential for the operation of mining equipment.
  • The existing cable-handling systems are typically comprised of component links which presently incorporate perceived design limitations resulting in greater than desired mining downtime for maintenance and servicing.
  • The CobraCo incorporates design features which address these limitations.
    • CobraCo has been granted an Australian patent over key design elements and Worldwide patent pending protection is in place.
  • The CobraCo design innovations may significantly reduce the frequency of maintenance and the total duration of mining downtime required to service and maintain cable-handling systems.
    • This represents significant time and cost savings for mining companies.

The CobraCo – Ease of Installation

  • The CobraCo is easy to assemble and disassemble quickly. Each plate is installed via the following steps (illustrated in figure 13):
    • The plate is positioned above the sidewalls, and a small distance behind its final installed position (about 20mm). In this position, the leading joint lug on the plate will align with the midway slot of the sidewall socket. The leading plate lugs are then inserted down into the slots of the sidewall sockets. The plate will now be at the correct height.
    • The plate is pushed forward, to its final position. At this point the LISD joints are engaged, but not yet locked.
    • The key is inserted into the corresponding slot in the joint and pushed flush with the assembly surface. The LISD joints are now fully engaged and locked, ready for service. The superior LISD fastened CobraCo link is strong, reliable, and robust, it does not suffer any of the shortcomings of the contemporary handler link.
  • Plate removal is the reverse procedure, except for the key removal which is first achieved by inserting a small screwdriver into one of the access grooves, located on either side of the key, and levering the key out. The plate is then slid backwards and removed. Either procedure is fast and easy, and can be completed in as little as twenty (20) seconds (provided the plate is accessible). Compare this to a plate replacement for the current cable handler, which may take over an hour, even when the plate to be replaced is initially accessible!