Which of the following is NOT listed as a common cause of bearing overheating?

• A. Electrical faults
• B. Poor lubrication
• C. Misalignment
• D. Overloading

Answer: (A)

Bearing overheating tends to come from mechanical conditions that raise rubbing and friction inside the bearing. The main culprits you’ll see in maintenance guidance are poor lubrication, misalignment, and overloading.

Poor lubrication allows insufficient or incompatible lubricant film to separate the rolling elements and races. When the film breaks down or is too thin, metal-to-metal contact increases, turning more of the input energy into heat and accelerating lubricant degradation.

Misalignment creates uneven loading and high local contact stresses. That irregular rubbing generates extra friction and heat in localized areas, pushing the bearing toward overheating even if the load isn’t exceptionally high.

Overloading pushes the bearing beyond its designed capacity, raising contact stress and friction across the raceway and rolling elements. This excess friction produces more heat and can shorten bearing life.

Electrical faults can cause bearing problems too, but they aren’t typically listed as a common cause of overheating in standard maintenance references. They’re more about electrical issues, such as bearing currents or insulation problems, which are a different failure mode than the everyday mechanical causes above.