Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How windproof are cable cars?

10.12.2007
A measuring system deals with the question as to the effects different wind loads have on cable cars.

Two researchers from the Vienna University of Technology (TU) have thrown light on vibration-control problems, an area little researched up to now and were able to account for the occurrence of lateral vibrations from various wind conditions right through to meteorological calm.

A measuring system which also measures wind direction and wind velocity on a two or three-dimensional basis is positioned on the cab of a cable car or on the chair of a chair lift. The behaviour of the vehicle on impact of the wind can thereby be measured in a wholly self-supporting manner. A dip in a transverse and longitudinal direction when vibrating, the driving speed and the position of the vehicle en route are of particular importance in this regard.

Observations by operating personnel of certain cable car systems have shown that a lateral vibration of the pendulum with large tilt angles can occur not only when the crosswind is blowing gustily but also when the wind is calm. In the meantime this has been quantified using measurement data. "On the basis of this measurement data, we confirmed that the cabs undergo vibratory excitation due to continuously circulating bicable tramways at certain velocities.

In the case of certain continuously circulating bicable tramways, this phenomenon is manifested at a lower driving speed range of approximately 2.0 to 3.0 metres per second. Normal driving speeds lie between 4 and 6 m/s", says Klaus Hoffmann, head of the Institute for Engineering Design and Logistics Engineering at the TU Vienna.

The measurements confirmed the suspicion that the afore-mentioned oscillations are due to periodical vortex shedding in the cab originating with the airsteam. Particularly strong vibrations occur when the vortex shedding frequency is identical to the natural frequency of the cab. Basically, the phenomenon can only be avoided if longer journeys are carried out at a driving speed range between 2 and 3 m/s.

"Thanks to the extensive European set of standards in accordance with which the cable cars are manufactured, there is a very high internationally comparable safety level today. Each cable car must undergo certain safety checks before it may be used by the operating company. Neveretheless, questions concerning the windproof capacity of cable cars in instruction manuals are often kept vague. Thus, the instruction manuals for monocable aerial ropeways, chair lifts or cabin tramways state the wind velocity at which the tramway can continue to be operated. At a constant crosswind of 50 to 65 km/h the availability limit of monocable aerial ropeways has normally been attained", says Robert Liehl, a doctoral candidate at the institute. Apart from wind sensors on the supports whose data is only partly representative for wind conditions along the entire cable car, the entire cable line must also be monitored in these situations by the operating personnel using a pair of binoculars. Hoffmann: "Even for lower average wind velocities, sudden gusts of wind can lead to critical situations. Our measurement data should supply additional information to be able to provide more accurate details of the vibration behaviour of cable car vehicles during different operating conditions."

During this research project the measuring system was patented in 2002 and has since then been used to carry out field measurements of wind loads and pendulum vibrations for different cable cars and chair lifts. Thanks to the support of the two world market leaders in cable car construction - Doppelmayr and Leitner - this measurement system can continue to be developed further.

Enquiries to:
Ao.Univ.Prof. Dipl.-Ing. Dr. Klaus Hoffmann
Vienna University of Technology
Institute for Engineering Design and Logistics Engineering
Getreidemarkt 9/Stg.4/4.Stk, 1060 Vienna
T +43/1/58801 - 30746
F +43/1/58801 - 30799
E klaus.hoffmann@tuwien.ac.at
Dipl.-Ing. Robert Liehl
Leitner GmbH
Niederlassung WIEN - VIENNA Branch
Perlhofgasse 2/1
A-2372 Gießhübl
T +43/2236 893 713 - 75
F +43/2236 893 713 - 55
E liehl.robert@leitner-lifts.com
Sent by:
Mag. Daniela Hallegger
Vienna University of Technology - PR and Communication
Karlsplatz 13/E011, A-1040 Vienna
T +43-1-58801-41027
F +43-1-58801-41093
E daniela.hallegger@tuwien.ac.at

Werner Sommer | idw
Further information:
http://www.tuwien.ac.at/pr
http://www.tuwien.ac.at/index.php?id=6737

More articles from Machine Engineering:

nachricht More functionalities: Microstructuring large surfaces with a UV-laser system
05.07.2018 | Fraunhofer-Institut für Lasertechnik ILT

nachricht A factory to go
04.07.2018 | Fraunhofer Institute for Manufacturing Engineering and Automation IPA

All articles from Machine Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

NSF-supported researchers to present new results on hurricanes and other extreme events

19.07.2018 | Earth Sciences

Scientists uncover the role of a protein in production & survival of myelin-forming cells

19.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>