Expansion team

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An extension team , also known as a frame assembly , is a hydraulic walking extension consisting of two or three extension frames . Extension straps are the oldest type of walking extension. They have been used in longwall mining in German hard coal mining since the mid-1960s . They have not been used since the early 1980s. The successor type of this step extension was the extension frame .

Structure and use

The extension team consists of two identical extension frames. The distance between these frames is up to one meter. Two hydraulic rams are built into each of these frames . Both stamps are on one level. Depending on the combination design, the hydraulic rams were installed either in the normal position or standing on the ram head. When installed upside down, the upper punches were protected by a protective tube. The stamps are connected in the upper area with a cap and in the lower area with a sole sleeper. The cap is usually divided. The two frames of the combination are connected to one another with a rear cylinder. Double-acting hydraulic cylinders are preferred for the back of the extension team. The rear cylinders are either connected to other extension frames or to the face conveyor . There are also extension teams in which a guide frame is mounted in the sole area between the extension frames. The return cylinder, the control unit and the hydraulic hoses are located in this frame. Each trailer can be operated by the neighboring trailer using the neighborhood switch. The guide frame is protected by a cover plate. Teams were also made with two extension frames with three hydraulic rams each. These expansion straps were designed for difficult conditions and were used in all storage conditions with seam thicknesses between 0.4 and 2.8 meters. In the lower area of ​​these combinations, the punches were attached to 300 millimeter wide runners made of spring band steel. The caps, in which the punch heads are stored, are also connected with wide spring steel strips. The disadvantage of extension teams is the relatively open design, as it offers the miners insufficient protection against falling stone and coal. In particular, the area of ​​the old man was not adequately shielded by the expansion work. Since there is only inadequate protection against slope breakouts , extension spans are only suitable for solid and easily manageable adjacent rock .

Back of the extension team

The individual expansion teams are moved forward hydraulically according to the progress of the dismantling . Various methods were tried out for the back of the extension team. For extension teams with two extension frames, a distinction is essentially made between two types of steps, the follow-up step and the overtaking step. With the retightening step, a frame is first pushed forward by the increment, then it is loaded again. Then the now set back second frame is released and advanced by the increment. As soon as the frames have reached their position, they are tightened again. When overtaking, the extension frames are offset from one another in the basic position. In the case of the back, the back frame is pulled forward so that it is half a step in front of the other frame. Small or large steps can be selected as the increment. The usual increments are between 0.4 and 1.5 meters. Both the large and small increments have disadvantages with regard to the load on the hanging wall. With large steps, it takes longer until the exposed hanging wall is supported again. With small increments, the multiple unloading and loading of the hanging wall can lead to a deterioration of the hanging wall. This case can occur in particular with resets that are very close together.

Individual evidence

  1. ^ A b Walter Bischoff, Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary . 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
  2. ↑ a b Volker Döhl, Manfred Deiß, Dieter Sauer, Fritz Böhle: Load reduction underground . On the influence of public measures on the humanization of work, Verlag Glückauf GmbH, Essen 1982, ISBN 3-7739-0380-4 , p. 48.
  3. ^ A b c d e Heinz M. Hiersig (Ed.): VDI-Lexikon Maschinenbau . VDI-Verlag GmbH, Düsseldorf 1995, ISBN 978-3-540-62133-1 .
  4. ↑ Heinz Kundel: coal mining . 6th edition, Verlag Glückauf GmbH, Essen, 1983, ISBN 3-7739-0389-8 .
  5. ↑ Heinz M. Hiersig (Ed.): VDI-Lexikon Energietechnik . Springer-Verlag Berlin-Heidelberg GmbH, Berlin 1994, ISBN 3-642-95749-8 .
  6. ^ A b c d e Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962.
  7. ↑ Ernst-Ulrich Reuther: Introduction to mining. 1st edition, Verlag Glückauf GmbH, Essen, 1982, ISBN 3-7739-0390-1 .
  8. ^ A b Gisela Brünner: Communication in institutional teaching-learning processes . Discourse-analytical investigations on instructions in company training, Publishing House for Conversation, Radolfzell 2005, ISBN 3-936656-20-7 , pp. 35–36.

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