What the world's longwall miners saw in Las Vegas.

Staff Reporter

MINExpo International 2000, held at the Las Vegas Convention Centre in Las Vegas during October 9-12, featured DBT's biggest display ever.

As previewed in the September edition of Australia's Longwalls, DBT put its first ever 2m-wide roof shields on display, presented as the "dancing shields".

Explaining the nomenclature, Bill Tate, president DBT America, said: “Our hydraulics are so precise and the electronic controls are so sophisticated that we can actually program the shields to move, synchronise them with dancers, and choreograph it to music.”

Several times a day, the shields went through a series of programmed moves together with a troupe of dancers brought out specially from Germany for this very purpose. The shields were identical to those to be installed at the CONSOL Energy’s Bailey mine.

The shields have a height range of 1.800-3.500mm and support resistance at average seam height 3.000mm at 320 bar setting pressure: 7.859kN; at 450 bar yield pressure: 11.053kN. The shields incorporate a double-telescopic hydraulic prop with a leg diameter of 400mm and leg force at 320 bar setting pressure of 4.019kN. Another features is the electrohydraulic shield control system PM 4. Each shield weighs 35 metric tons and has corrosion protection.

Other offerings were the CST 65 face-conveyor drive system, said to be the world's most powerful AFC drive system. Developed in a joint venture with Dodge Rockwell Automation since 1991, the drive system incorporates planetary gearbox with integrated CST multi disc clutch and DBT drive control unit, especially developed for face conveyor drives. Since the first installation at Twentymile (US) in 1995, over 100 systems have been sold worldwide. Advantages include no-load motor start-up, minimum voltage drop through staggered motor start, synchronised heavy-load start-up, short-term use of kinetic motor energy, maximum total torque available, start-up of overfilled conveyors without problem.

DBT’s newly developed class 35 drive frame with a solid sprocket was also presented. The sprocket forms one unit with the shaft and the bearings and may be exchanged underground without removing the gearboxes. The cross frame allows face conveyors up to 1.142mm width and stageloaders up to 1.332mm width. Maximum installed power 2x800kW. The tail drive is tensionable with only one tensioning cylinder located at the gobside of the drive frame providing easy access for maintenance.

Also featured were six shield supports and six line pans; a display wall for the PM4 system; a type SB 0916 crusher; and a new aluminium cable handling system, of specific interest for the US-market.

Other exhibits will include standpartners, such as chain from the Thiele company and longwall pipelines for high-pressure and return lines as installed inside the face-conveyor spillplates from the Hamacher company. (A review of Hamacher's high-pressure pipes will be published on ILN on October 30.)

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