Exaggerate

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Exaggeration describes the situation in mining that the hoist cage only comes to a standstill above the suspended bank when hoisting the shaft . In particular, since steam engines and electric motors have been used to drive the hoisting machines, there is a risk that the baskets will be pulled to the upper end of the conveyor frame as a result of a malfunction due to their greater speed .

causes

The causes for exaggeration are very different. For example, an error in the control system can result in the travel brake not being applied when the loaded conveyor is at the upper stop. As a result, the conveyor is pulled downwards due to its own weight and reaches such a high speed that it moves into the sump . Another cause of the exaggeration can be a defect in the switch responsible for the entry monitoring. Then the conveyor is not braked appropriately and moves beyond the top stop. Mechanical defects in control devices can also lead to the conveying means not being braked accordingly and thus excessive. Human error can also be a cause of exaggeration.

consequences

The headframe can be damaged by the impact against the sheaves . As a result, the rope can tear . When conveying traction sheaves , the miners are endangered by both hoisting cages hanging on the same rope . Entry monitoring is used as protection today. A magnetic switch in a glass tube filled with protective gas is typical. So that the basket does not go under the sheaves, there is an overdrive protection and a bumper beam to stop the conveyance completely .

Incidents in operational practice

On September 28, 1898, during the cable trip at the General Blumenthal colliery, the hoisting cages were overdrawn, killing 17 miners. On March 25, 1926, the cages at the Oberhausen colliery were exaggerated during the cable car ride . The upward moving cage was pulled under the bumper. The force was so strong that the hauling rope broke. When it fell back, the basket touched the safety supports . The basket, which was drifting downwards, was pulled into the shaft sump with full force when it was retracted. This basket was pulled around the turning wood relocation and severely deformed. 13 miners were killed in this incident. In 1983 there was an exaggeration on a shaft system on a blind shaft conveyor system, with the conveyor cage being driven at high speed into the thickened guide rail and then against the impact carrier. A miner was slightly injured in this incident.

Individual evidence

  1. ↑ a b c Technical requirements for shaft and inclined conveyor systems (TAS). Verlag Hermann Bellmann, Dortmund 2005.
  2. ↑ Patent No. 73616 Excessive protection for shaft conveyance . Online (accessed January 27, 2012; PDF; 225 kB).
  3. ^ Arnsberg district government: Exaggerating a shaft hoisting system . Online (accessed January 27, 2012).
  4. ^ Arnsberg district government: Exaggerating the counterweight of a medium-sized cable car system .
  5. ↑ District government Arnsberg: Exaggerating on a single-bobbin sinking system .
  6. ^ Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
  7. ↑ Winfried Sindern, Olivier Gronau: Steel wire ropes - proven service providers of shaft hoisting systems. In: Ring Deutscher Bergingenieure eV (Hrsg.): Mining. Volume 61, No. 4, Makossa Druck und Medien GmbH, Gelsenkirchen April 2010, ISSN  0342-5681 , pp. 155-164.
  8. ↑ Joachim Huske: The coal mine in the Ruhr area. 3rd edition, self-published by the German Mining Museum, Bochum, 2006, ISBN 3-937203-24-9 .
  9. ↑ Cable trip accident at the Oberhausen colliery .
  10. ↑ District government Arnsberg: Exaggerating the funding of a medium-sized cable car system .