Trailer Separation Mayhem

lowboy trailer gooseneck


John R. Yannaccone, P.E., Sr. Mechanical Engineer
Case Synopsis: A heavy duty equipment hauler was delivering a large piece of equipment to an industrial plant. After the equipment was off-loaded, the driver wanted to reconfigure the low-boy gooseneck trailer by removing a section of the trailer so it was shorter for the trip back to his employer. The middle section of the trailer needed to be unbolted and removed to allow the front and rear section of the trailer to be re-connected for the return trip. The driver asked if the industrial plant had anyone to assist him in shortening the trailer, to which they offered one of the plant’s truck mechanics to assist him.
The trailer manufacturer had specific instructions regarding the sequence of steps to safely separate the mid section of the trailer, using cribbing and the hydraulics of the gooseneck to manipulate the trailer. The truck driver was directing the plant mechanic as they worked together to remove the bolts holding the center section of the trailer. During the process, the driver instructed the mechanic to tap/drive out a shim between two sections of the trailer. When the shim came free, a portion of the trailer dropped down and landed on the foot of the mechanic, trapping it under the trailer. Other workers at the plant used a forklift to lift the trailer section off the mechanic’s foot. He suffered severe crush injuries to his foot, which resulted in permanent disability.
Expert Analysis: Review of the instructions in the trailer operator’s manual included procedures for a safe method to remove the mid section of the trailer without dropping it. Review of the testimony of both the driver and the mechanic clearly indicated they did not follow the proper procedures as described in the operator’s manual. Additionally, the driver, who claimed to have separated and connected the mid section of the trailer many times prior to the incident, should have known that the shim should have separated freely as opposed to needing to be driven out from between the sections. Rather than recognizing this problem, he directed the mechanic to perform improper steps which resulted in the loss of control of the load, dropping of the trailer, and injury to the mechanic. Additionally, the driver’s employer did not provide their drivers a written disassembly procedure for the trailer, forcing them to rely on their memory for the proper procedure to reconfigure the trailer. Had the driver followed the proper disassembly procedure for reconfiguration, they should have been able to safely reconfigure the trailer.
Result: Prior to trial, a settlement was reached with the equipment transport company.
John R. Yannaccone, P.E., Sr. Mechanical Engineer with DJS Associates, Inc., can be reached via email at or via phone at 215-659-2010.

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Tags: John R. Yannaccone | Mechanical Engineer


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