longwall mining




face services



Face Services

Face services include high and low voltage electric power, water, compressed air, hydraulic fluids and possibly pumping. These are required for:

  • High voltage power, increased over time from 415v to the present preference for 3.3kv; required via trailing cables to power the shearer and via fixed cables for the main and tailgate drives

  • Most faces now have lights attached to the chocks on a 240v supply via interchock cables

  • Low voltage power is required for monitoring (typically operating parameters and location of the shearer, chock operating parameters and gas concentrations at certain locations) and for control of chock operations.

  • Water is required for cooling of motors (main and tailgate drives and shearer), for dust control (on the shearer drums and the crusher) and for fire fighting precautions. It may also be needed for secondary roof bolting or drilling for various purposes on the face, particularly during face recovery operations.

  • Compressed air is seldom used on the main face equipment but is frequently required for pumping, roof bolting or drilling as above and possibly for ventilation purposes such as operation of venturi's. It may also be useful for machine maintenance and repair purposes.

  • Hydraulic fluid, usually a soluble oil/water emulsion, is required throughout the face from the boot end to the last support at the tailgate. It is normally supplied in a closed circuit with a return line running the length of the face back to the pumps in the maingate.

  • The pumping referred to here is of waste water which may collect at low points on the face or in the gate roads and needs to be removed, possibly from one end of the face to the other.

It is normal for water and compressed air to be supplied from the mine reticulation systems, which would be in steel pipes in the gate roads up to a point close to the face and would then be carried onto and across the face in hoses with outlets at suitable intervals. The water supply to the shearer would usually be run onto the face separate to the supply for other purposes and may require a high pressure line for dust suppression purposes.

Electric power and hydraulic fluid is supplied from equipment usually in the maingate or adjacent roadway, consisting of transformers, switchgear and electrical distribution boxes, hydraulic pumps and tanks. There is also usually an enclosure containing face monitoring and communication equipment.

On early mechanized longwalls, all this equipment was mounted on skid or rail mounted bases in a long line alongside the maingate conveyor. The bases were all connected together and were dragged forward as the face advanced, in some cases with a winch and in others with a large hydraulic cylinder mounted on a base with a large staker prop to the roof, also hydraulically operated. The latter usually used a chain to pull the equipment forward.

All this train of equipment is known as a "Pantechnicon", a name generally shortened to "Pantec".

Later developments have included mounting the pumps remotely, sometimes in the main headings in specially constructed pump stations, with the fluid being carried in steel pipes for most of the distance to the face. This has the advantage of the pumps being set in good, clean conditions and not having to be moved frequently, sometimes being used for more than one longwall block. The disadvantage is having to have pipes in the maingate carrying high pressure fluids with associated safety issues and pressure losses in the pipes.

22b More recent longwalls have a set-up between the two set-ups described above, where the pumps are located in a roadway adjacent to the face some distance outbye the face position (of the order of 500m) and relocated when the face is somewhat closer (usually before their location becomes part of the "hazardous zone" where additional protection such as flame-proofing is required). In this way the pumps, etc can be located in relatively good conditions away from the immediate face area, are moved less frequently than if they were in the face area, but have a smaller reticulation system than the outbye stations. The transformers supplying power can also be located a similar distance from the face.

A large number of cables and hoses have to be run between the Pantec or remote pump stations and transformers and this requires some type of cable handling arrangement. To protect them in the area closer to the face, they are normally run in a covered steel trough run alongside the BSL, known as a "Rigid Bretby". The enclosed trough runs around the back of the maingate drive onto the face itself.

With a Pantec there is only a very short distance from the Rigid Bretby to the end of the Pantec and the cable/hose lengths required are fixed.

With a remote pump station/transformer set-up the cable/hose lengths are very variable Rather than try to manhandle and add/remove lengths, a monorail system is typically used. Loops of cables and hoses are attached to monorail trolleys such that the loops can hang almost roof to floor or can be stretched out almost horizontally, the difference in overall length being the distance required for the pump/transformer relocation. The monorail consists of short sections of rail which are hung from roof bolts. As the face approaches, rail sections are removed and re-hung outbye ready for the next relocation of the pumps/transformer.

Other items (eg tool boxes, fire fighting equipment) can also be hung from the monorail if desired.

On the face itself, some cables and hoses require connection to every chock. These are made in short lengths, known as interchock hoses or cables, and often hung together in a cover to make handling easier. Sockets/connectors are mounted on the chocks for attachment of these services with through connections installed to connect to the next chock in line.

Cables and hoses which require no or infrequent outlets/connections are usually run along brackets on the AFC back plates.

Austdac Equipment

Macquarie Manufacturing Pty. Ltd.