Expertly Speaking

Engineering Animation: Steering Mechanism – Tie Rod Failure


Hugh Borbidge, BSME, Director of Engineering Animations

This animation illustrates a basic configuration of the linkages that steer the wheels when the steering wheel is turned. The steering wheel essentially controls one wheel. The second wheel is connected to the first by a tie rod. This tie rod allows both wheels to steer the vehicle. Should the tie rod fail, the steering wheel would only be able to continue to control one wheel, while the second wheel would be uncontrollable. At high speeds this could have tragic consequences.

 

 

Hugh Borbidge, BSME, Director of Engineering Animations with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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Phillies

What do the Philadelphia Phillies have to do with Collision Reconstruction?


James R. Schmidt, Jr., BSME, Collision Reconstruction Engineering Analyst

Using a high-resolution, to-scale aerial image of Citizens Bank Park, the home of the Philadelphia Phillies, an evaluation of the in-game third to home running speed of Phillies outfielder Roman Quinn was performed, as he raced home and scored the walk-off winning run against the Mets on a Bryce Harper single to right field on 8/14/20.

Readily available video footage from the game was analyzed, including breaking the footage apart and synchronizing two different camera views contained therein.

Philadelphia Phillies

Philadelphia Phillies

Roman Quinn rounds third and heads for home. When he gets to the edge of the grass surrounding home plate, he goes into a diving posture, then dives and sneaks his hand in, ahead of the tag.

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Shower Door

Shattering Shower Door


Lt. Col. Bryan Smith, Construction Site Safety Consultant

Case Description: The plaintiff was exiting her relative’s home shower when the shower’s glass door shattered into pieces, and shredded her leg.

Expert Analysis: A field inspection was performed approximately three and a half years subsequent to the incident at the request of the homeowner’s insurance company, in order to determine if the plaintiff’s actions were negligent and causal to the incident. Photos and measurements were taken at that time and they evidenced that the shower enclosure door had been replaced in-kind prior to the site inspection. The moveable portion of the shower door was supported by two rollers on a horizontal rail. The rail had cushioned bump-stops at each end of travel.

As the shower user pushed the sliding door open or closed, with more force than necessary to reach the bump stops, the sudden cessation of travel when the roller hit the bump-stop caused the door to rotate in the upward direction. The design of the door hardware included a cam locking device, which was placed below the horizontal track to prevent the track rollers from jumping off the rail. The cam lock device was to be situated and adjusted such that it left a space narrower than the roller’s engagement of the track’s upper surface (see the space between the two yellow arrows).

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Reconstruction of a Vehicle-Bicycle Collision


Robert T. Lynch, P.E., Principal Collision Reconstruction Engineer

A doctor would frequently ride his bicycle from his home to the train station as part of his commute to work. One morning before sunrise, the doctor was riding along on a sidewalk before he crossed a six-lane roadway where he was struck by a vehicle after nearly crossing all six lanes of traffic.

Surveillance video was provided from a nearby business that captured the pre-impact movements of both the bicyclist and the vehicle. However, this video did not capture the actual point of impact, as the camera was located too far away (over 500 feet), and several trees were obstructing the clear line of sight. Also, the ambient illumination was still dark, effecting the clarity of the video.

DJS was asked to use the provided surveillance videos to reconstruct the incident to the greatest extent that it could be reconstructed. The roadway was documented with high-definition surveying (HDS) laser scans, drone aerial images and video, and terrestrial photographs and video, with specific focus on documenting the environment in the vicinity of the surveillance cameras. Using this data, an accurate, to-scale, three-dimensional model of the environment was created. The surveillance video was then camera-matched to the environment. The movements of both the bicyclist and vehicle were tracked through the environment and pre-impact speeds were able to be determined.

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Towing Fire Investigation


R. Scott King, BSME, CFEI, Principal Automotive / Mechanical Engineer

Courts have long established that a person can be qualified to provide expert testimony to a judge or jury if that person possesses the knowledge, training, or experience in a specific subject matter. Experts typically apply those qualifications to physical evidence or other data, testimony, and discovery production to formulate their opinions. When possible, experts may rely on relevant industry guidelines, recommended procedures, and investigative strategies to serve as a foundation for their opinions. A recent commercial vehicle fire investigation drew from a multitude of these sources to establish the fire’s origin and root cause.

A commercial motor coach suffered a mechanical malfunction resulting in its roadside disablement. A regional commercial towing operator was dispatched to tow the coach back to its terminal for diagnosis and repairs. During the towing, the tow operator was alerted by passing motorists to a potential emergency. Upon stopping his vehicle, the tow operator discovered thick smoke emerging from the rear wheels of the motor coach. Realizing he could not extinguish the fire; the tow operator summoned fire personnel and disconnected his tow truck from the coach. While not completely burned, the coach suffered catastrophic fire damage.

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What is the NHTSA?


Leslie Lovre-King, Technical Assistant

Ensuring automotive safety is the prime mission of the National Highway Traffic Safety Administration (NHTSA). Among others, NHTSA accomplishes this mission by establishing vehicle safety ratings, collecting and maintaining crash statistics, and implementing public safety awareness initiatives. Perhaps the most common association the motoring public has with NHTSA is through its role in the automotive recall process; however, what many people may not know is that most vehicle recalls are initiated not by NHTSA, but by individual vehicle manufacturers.

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