R. Scott King, BSME ::::
Background: Historically, automotive power steering mechanisms have been relatively simple hydraulic systems comprised of a belt-driven pump, hoses and valves. These are time-tested systems, providing high levels of reliability and durability. Of course, steering assist is required during low speed steering maneuvers, but straight-ahead driving, and even higher speed turns, typically do not require power assistance. Thus, if these systems have a systemic shortcoming, it is that they require power – and thus consume energy and fuel – whenever the engine is running, whether power assist is required or not. Newer power assist systems, however, are smarter. They provide steering assist only when required. But are they as reliable? A recent case suggests perhaps not.
Case Synopsis: The operator of a 2012 Nissan was involved in an intersectional collision while attempting a left turn. Midway through the turn, the steering reportedly “locked”, affecting the operator’s ability to successfully negotiate the turn, resulting in a collision. With this allegation, the operator’s carrier initiated a forensic mechanical evaluation.
Engineering Analysis: During the examination, engineers focused first on the primary mechanical systems that contribute to vehicle handling and control characteristics, including the steering. After determining these systems were in good condition, focus shifted to the power steering. As expected, this was a “smart” system, utilizing an electronic hydraulic pump and related sensors, wiring, and control modules. During initial testing, the system operated normally; however, during extended operational tests – which simulated the bumps and vibrations encountered during normal driving – engineers detected an abrupt reduction in pump pressure. After refining their tests, engineers identified a defective wiring connector in the main power supply, resulting in intermittent pump operation.
Conclusion: These findings facilitated fair resolution of the insured’s claim and provided a clear and convincing path to successful subrogation. (Scott King, BSME, can be reached at 215-659-2010 or via email at experts@forensicDJS.com)Categories: Case Studies