Characterization of Semi-Float Axle Shaft Bending Fractures

Semi-float rear axles are used today throughout the world on most passenger cars, sport utility vehicles, and many light trucks. The axle shaft in the semi-float axle assembly serves two functions; to transmit torque, and to carry the vehicle weight. These shafts are typically conservative in design and extremely reliable. However, they will occasionally fracture by bending overload as a result of an accident such as side impact with another vehicle or obstacle, or a rollover situation. These fractures have been, on occasion, grossly mischaracterized leading to an erroneous conclusion as to the cause of an accident. It is the intent of this work to serve as a guide in recognizing the cause of bending fractures that may occur in this type axle shaft. Fortunately, these fractures are easy to identify and the information they provide is absolutely reliable.