Test, Evaluation and Failure Analysis of Automotive Scissors Jacks

Abstract

Automotive scissors jacks have rapidly grown in popularity in past years because of their light weight, low cost and ease of use and storage. However, they may be a potential safety hazard if the scissors jack is not adequately designed, properly assembled or correctly used. This paper summarizes results from a test and evaluation program performed by the National Highway Traffic Safety Administration involving 120 automotive scissors jacks selected from 24 models and made by 14 different manufacturers. In conjunction with the test results, a mathematical model was introduced to describe the load supporting characteristics of a variety of scissors jacks. The analytical results agree fairly well with the test results. A failure mode and effects analysis was performed to analyze four observed major failure modes of the scissors jacks; i.e., collapsing, toppling over, unable to raise or lower the vehicle and penetration of the vehicle frame.