Rope safety

In conveyor technology, rope safety is a safety factor by which a rope must be able to withstand greater loads than its maximum rope force. This factor always relates to a pull in the straight leg. The greatest possible rope safety should reduce the risk of rope breakage and the resulting damage or, if possible, prevent it entirely.

Basics

Every hoisting rope has a certain load-bearing capacity, which depends on various factors. In the course of operation, the rope is heavily stressed and its load-bearing capacity is weakened. If the rope were to be loaded with such a weight that the load is as high as the load-bearing capacity of the new rope, it would tear. For this reason, hoisting ropes are only loaded with part of their breaking force. The relationship between the rope breaking force and the maximum rope force is called rope safety. However, rope safety is handled differently in the various conveyor systems. Rope drives for hoists, series hoists and cranes are designed in accordance with DIN 15020. Ropes for cable cars are dimensioned according to EN 12927. Hauling ropes for shaft hoisting systems are dimensioned in accordance with the technical requirements for shaft and inclined hoisting systems.

History

As a result of several accidents due to broken ropes, the ropeway commission was founded towards the end of the 19th century. The task of this commission was to improve the safety of shaft hoisting systems. This commission paid special attention to the cable breaks that often occur on hauling ropes. The safety devices for conveyor baskets used up to then had not proven themselves in practice, so that the safety of the conveyor systems could only be achieved with the highest possible safety factor. However, there were different opinions about the level of the respective safety factor. So the idea was that the breaking strength of a hoisting rope when traveling by rope must correspond to twelve times the weight of the hoisting cage and five times the weight of the hoisting rope from the sheave to the bottom of the shaft . At the beginning of the 20th century, rope safety was regulated in the Dortmund Mountain Police Ordinance in such a way that rope safety for rope travel must be at least 8 times the maximum load for rope travel and 6 times the maximum load for conveyance when hoisting the shaft . For the hoisting ropes used for traction sheave conveyance, an initial safety of 9.5 for the rope journey and 7 for the conveyance applied. In the 1930s, DIN Berg 1254 required a nationwide rope safety of six times for load travel (funding) and eight times for rope travel until the end of the rope's lay-up time. In the case of traction sheaves, 9½ times the rope safety when traveling by rope and 7 times the rope safety when conveying.

Current regulations for shaft hoisting systems

Today, rope safety for hoisting ropes in mining is regulated in the technical requirements for shaft and inclined conveyor systems (TAS). The rope safety regulated here has been derived from long observation in operational practice. When calculating the rope safety, the TAS differentiates between the rope safety for shaft hoisting ropes and stage ropes and the rope safety of other ropes. For rope safety when traveling by rope, the TAS requires that the minimum safety factor (v) is equal to or greater than 9.5 - 0.001 L, and for goods transport, the minimum safety factor (v) must be at least equal to or greater than 7.5 - 0.0005 L. be. When L is the maximum distance between the pulley and the conveyor basket applies here simplifies the true depth .

The following applies to the rope safety of hoisting ropes and stage ropes:

${\ displaystyle rope safety = {\ frac {determined breaking force} {static load}}}$

The following applies to the rope safety of other ropes:

${\ displaystyle rope safety = {\ frac {calculated breaking force} {static load}}}$

Source:

The static load is the weight of the hoist cage, upper and lower rope and payload. The breaking force determined is the sum of the measured breaking forces of all individual wires of the respective rope. The calculated breaking force must be determined before the rope is laid. The calculated breaking force is the breaking force, which is the sum of the products of the individual nominal wire cross-sections and the nominal tensile strengths of each wire of the respective rope that is agreed to be load-bearing. A rope is ordered based on the calculated breaking force.

Regulations outside of mining

The European regulation for elevators, DIN EN81, applies to elevator systems. A minimum rope safety of 12 applies here. This regulation replaces the Technical Rules for Elevators (TRA), in which a calculated rope safety of 14 applies. In the case of rope drives for hoists , series hoists and cranes , the rope drives are dimensioned in accordance with DIN 15020. Here, the requirement for fatigue strength is taken into account. In the case of cable cars, the regulation for the construction and operation of cable cars, the BOSeil including the implementation regulations apply. A minimum rope safety of 4.5 applies to pull ropes and a minimum rope safety of 5 to haul ropes. The safety requirements for ropeways for passenger traffic are regulated in EN 12927. Different safety factors apply to the pull ropes . A safety factor of 4.2 applies to pull ropes of funicular railways, a safety factor of 3.8 applies to pull ropes of double-cable pendulum lifts with suspension cable brake, and a safety factor of 4.5 applies without suspension cable brake. A safety factor of 4.0 applies to pull ropes on unidirectional two-way cable cars. In the supporting cables , a safety factor of 2.7 when the support cables are fitted with support rope brake applies, and a safety factor of 3.15 when the suspension ropes without carrier truck brakes are fitted.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Klaus Feyrer: Wire ropes. Dimensioning, operation, safety. Second revised and expanded edition, Springer-Verlag Berlin Heidelberg, Berlin 1994, ISBN 978-3-662-06770-3 , pp. 243–245.
↑ ^a ^b ^c ^d ^e ^f ^g Karl-Heinz Wehking: Running ropes . 3rd completely revised edition, Expert Verlag, Renningen 2005, ISBN 3-8169-2497-2 , pp. 21, 33-38.
↑ ^a ^b M. Schwahn: Dimensioning the safety factor of hoisting ropes. In: Polytechnisches Journal . 330, 1915, pp. 133-136.
^ ^A ^b H. Herbst: Results of the negotiations of the Prussian Ropeway Commission. I. In: Glückauf, Berg- und Hüttenmännische Zeitschrift. Association for Mining Interests in the Oberbergamtsiertel Dortmund (Ed.), No. 2, 61st year, January 10, 1925, pp. 33–39.
↑ F. Mechtold: Lifting and handling equipment; Basics - types - applications . 5th completely revised and greatly expanded edition, Springer Verlag Berlin-Heidelberg-New York, Berlin 1969, pp. 499-500.
^ Report of the ropeway commission for the Oberbergamtsiertel Dortmund . In: Glückauf, Berg- und Hüttenmännische magazine. Association for mining interests in the Oberbergamtsiertel Dortmund (Ed.), No. 18, 41st year, May 6, 1905, pp. 557-574.
↑ Fr. Herbst: The calculation of the safety factor of the shaft hoisting ropes with separate consideration of the weight of the conveying load and the rope weight . In: Glückauf, Berg- und Hüttenmännische magazine. Association for mining interests in the Oberbergamtsiertel Dortmund (ed.), No. 47, 49th year, November 22, 1913, pp. 1936–1940.
↑ A. Vierling: Status of the main shaft extraction with regard to safety and performance . In: Journal of the Association of German Engineers, Volume 78, No. 29, July 21, 1934, pp. 865–870.
↑ ^a ^b ^c Technical requirements for shaft and inclined conveyor systems (TAS). Hermann Bellmann Verlag, Dortmund 2005, sheet 6/4.

[Quelle_1-1] ↑ ^a ^b ^c ^d ^e ^f Klaus Feyrer: Wire ropes. Dimensioning, operation, safety. Second revised and expanded edition, Springer-Verlag Berlin Heidelberg, Berlin 1994, ISBN 978-3-662-06770-3 , pp. 243–245.

[Quelle_2-2] ↑ ^a ^b ^c ^d ^e ^f ^g Karl-Heinz Wehking: Running ropes . 3rd completely revised edition, Expert Verlag, Renningen 2005, ISBN 3-8169-2497-2 , pp. 21, 33-38.

[Quelle_3-3] M. Schwahn: Dimensioning the safety factor of hoisting ropes. In: Polytechnisches Journal . 330, 1915, pp. 133-136.

[Quelle_4-4] A ^b H. Herbst: Results of the negotiations of the Prussian Ropeway Commission. I. In: Glückauf, Berg- und Hüttenmännische Zeitschrift. Association for Mining Interests in the Oberbergamtsiertel Dortmund (Ed.), No. 2, 61st year, January 10, 1925, pp. 33–39.

[Quelle_5-5] F. Mechtold: Lifting and handling equipment; Basics - types - applications . 5th completely revised and greatly expanded edition, Springer Verlag Berlin-Heidelberg-New York, Berlin 1969, pp. 499-500.

[Quelle_6-6] Report of the ropeway commission for the Oberbergamtsiertel Dortmund . In: Glückauf, Berg- und Hüttenmännische magazine. Association for mining interests in the Oberbergamtsiertel Dortmund (Ed.), No. 18, 41st year, May 6, 1905, pp. 557-574.

[Quelle_7-7] Fr. Herbst: The calculation of the safety factor of the shaft hoisting ropes with separate consideration of the weight of the conveying load and the rope weight . In: Glückauf, Berg- und Hüttenmännische magazine. Association for mining interests in the Oberbergamtsiertel Dortmund (ed.), No. 47, 49th year, November 22, 1913, pp. 1936–1940.

[Quelle_8-8] A. Vierling: Status of the main shaft extraction with regard to safety and performance . In: Journal of the Association of German Engineers, Volume 78, No. 29, July 21, 1934, pp. 865–870.

[Quelle_9-9] Technical requirements for shaft and inclined conveyor systems (TAS). Hermann Bellmann Verlag, Dortmund 2005, sheet 6/4.