0

Full Content is available to subscribers

Subscribe/Learn More  >

Safety of Fitness Equipment Cables

[+] Author Affiliations
Ralph L. Barnett

Triodyne Inc., Glenview, ILIllinois Institute of Technology, Chicago, IL

Paper No. IMECE2013-63876, pp. V015T12A017; 9 pages
doi:10.1115/IMECE2013-63876
From:
  • ASME 2013 International Mechanical Engineering Congress and Exposition
  • Volume 15: Safety, Reliability and Risk; Virtual Podium (Posters)
  • San Diego, California, USA, November 15–21, 2013
  • Conference Sponsors: ASME
  • ISBN: 978-0-7918-5644-4
  • Copyright © 2013 by ASME

abstract

There is a family of fitness machines that provides a manual workout task requiring the user to push or pull against a resistance provided by a stack of weight plates. The weight system is usually linked with a single cable to a gripping or user interface device to produce a constant resistance. A fracture of the tensioned cable along its length or at its end connectors causes a sudden acceleration of the grip or other interface device driven by the operator’s push or pull. The sudden loss of resistance often results in an exerciser pulling a heavy bar into his or her face. Because falling weights, accelerating grips and rapidly unloading muscles are all hazardous, manufacturers of exercise machines want to maintain the structural integrity of the cables. To accomplish this, manufacturers usually recommend “scheduled servicing” of their cables. This Preventive Maintenance (PM) strategy is frustrated by nylon sheathing that hides the cable failures. Further, the swedged or silver soldered connectors often fail covertly by internal fatigue fractures. A more effective PM strategy has been adopted by many manufacturers called “Scheduled Replacement”; they advocate annual cable replacement. Here the nemeses are sloth and greed, best expressed by the philosophy, “if it ain’t broke, don’t fix it.” As a first consideration of fault tolerant design, a redundant duplication of the cable system was added to a fitness machine; this is called “active redundancy.” This paper demonstrates the inadequacy of active redundancy for eliminating the catastrophic failure mode. Instead, the adoption of a “dormant/standby” redundancy is shown to provide the requisite safety. The proposed system not only eliminates the “fail-to-danger” mode, it provides the most economical use of the cable in the sense that it never discards a cable until its life is exhausted.

Copyright © 2013 by ASME
Topics: Safety , Cables

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In