Pennsylvania Attorneys Discuss Wheel Runoff Accidents

February 7, 2019

When a wheel fails, it can pose a sudden danger to a moving vehicle and others using the road. Accidents, where a wheel comes off the vehicle, are called wheel runoff accidents. They are often catastrophic and fatal, but generally preventable.

A Matter of Torque

After an accident, information is often gathered through a forensic investigation to determine the exact cause and what factors brought it about. One crash forensics firm has taken the time to explain what they know about wheel runoff accidents, and they point to two major areas: the wheel mounting system, and the hub and wheel bearing assembly.

The failure of a wheel mounting system is often attributed to the way the wheel itself was installed. Lug nuts and bolts rely on a specific amount of pressure to hold the wheel in place. The mounting must be tight enough that friction and torque pressure will keep the wheel secure, but not so tight that it causes the bolts to break.

Excess lubrication, paint on the wheels that is too thick, and anything else placed between the wheel and the hub assembly can cause the wheel to behave as though it is bolted on too loosely. A loose connection called a soft joint by the forensic team, allows the wheel to move around and detach from the hub assembly.

Over-torquing is dangerous because it hinders the ability of the bolts to maintain their shape. There is a certain degree of flexibility that the bolts have in which they can handle the pressure of movement and return to their shape. When the pressure on them exceeds their ability to maintain their form, they are prone to break. Tightening the lug nuts too much can cause this, as added torque puts additional pressure on the bolts.

Forensics points to the use of impact wrenches as a contributor to the problem. While passenger cars are designed to operate on 100 foot-pounds of torque, for instance, the impact wrenches used on them produce 300-500 foot-pounds of torque.

Other Issues

Car owners are less likely to be installing axle nuts in their own garages but need to be aware of the danger of an improper installation. An axle nut attached too tightly can cause excess friction that wears down the axle, while one attached too loosely can move around and pose the same danger as a loose wheel. Other causes of axle failures are tied to a lack of lubrication, or overloading the vehicle, both tending to result in the system failing in the same way and causing wheel runoff accidents.

One of the responsibilities of car ownership is proper maintenance, and wheels cannot be overlooked in this. Whenever a wheel needs to be removed, it is vitally important that it is replaced in a way that will hold it in place properly. When this is overlooked, people are injured.

If you have been injured due to improper maintenance or a defective automobile part, contact us today to discuss your options.