A Force and Energy Analysis: Vehicle Extraction with a Tow Strap

More and more stores and catalog mail order houses have been offering the consumer a new type of towing device. Braided ropes and woven straps are being sold as replacements for towing chains and cables. Usually made from polypropelene or similar materials, they are strong, lightweight, inexpensive and easy to use. Unfortunately they are also easy to misuse; serious accidents have occurred. This paper presents a force, deflection and energy analysis of these straps in some idealized, but typical situations. It is shown that the relatively high strength but low flexibility can lead to point-of-attachment failures.