How is bearing failure diagnosed?
The symptoms of bad wheel bearings include:
- Noise: A humming, rumbling or growling noise that increases with acceleration or as the vehicle turns.
- Looseness, excessive play in the steering wheel (vague steering);
- Steering wheel vibration which changes with the vehicle speed or as the vehicle turns;
- ABS malfunctioning.
How is the fatigue life of rolling element bearings determined?
The fatigue life of bearings depends on many factors and variables, such as the size and direction of the loadings, the geometry and roughness of the contact surfaces, the kind of material, the operating temperature, applied lubricant, lubrication conditions, rolling speed, and sliding in the contact area [5–7].
How is failure defined in a roller element bearing?
Rolling-element bearings use rolling elements interposed between two raceways, and relative motion is permitted by the rotation of these elements. It describes failure by wear, failure by fretting, failure by corrosion, failure by plastic flow, failure by rolling-contact fatigue, and failure by damage.
What is the normal mode of failure of a rolling element bearing and why?
The two main failure modes of a bearing are wear and fatigue. Ball and roller bearings which are well lubricated , perfectly sealed and running at moderate load and speed, will not exhibit sufficient wear that will cause a failure even after long service.
What are five things that could cause premature bearing failure?
Top 5 Reasons for Premature Bearing Failure
- Fatigue. What It Is. The most common cause of bearing failure is fatigue, with 34% of all premature bearing failures being attributed to fatigue.
- Lubrication Problems. What It Is.
- Incorrect Mounting. What It Is.
- Improper Handling. What It Is.
- Contamination. What It Is.
How long does wheel bearing last?
about 85,000 to 100,000 miles
Most wheel bearings last about 85,000 to 100,000 miles before they need to be replaced. Some vehicles have wheel bearings that last a lot longer, and some vehicles need them replaced fairly quickly. It all depends on the quality of your wheel bearings and your usual driving conditions.
What is fatigue lifetime?
Fatigue life is a mechanical and scientific term that relates to how long an object or material will last before completely failing because of concentrated stresses. In most cases, fatigue life is calculated as the number of stress cycles that an object or material can handle before the failure.
What are signs of fatigue failure in a rolling contact bearing?
Fatigue failure is characterized by spalling (flaking) on the raceways and/or the recirculating elements (balls or rollers). As the bearing operates—carrying a load and experiencing forces due to its motion—the repeated stresses on the recirculating elements and raceways cause the material to fatigue.
What is the main mechanism of rolling element bearing failure?
Mostly the ball and roller bearing failures are caused by interference of the lubricant supply to the bearing or inadequate delivery of the lubricating oil to the raceway contact [1], [8]. Ball bearings can be divided into three categories, i.e. radial contact, angular contact, and thrust.
How do roller bearings fail?
As shown in Figure 2, the prime reason roller bearings fail to reach life expectancy is due to lubricant contamination from particles. To the naked eye, a lubricant sample might look clean, but in fact, contains tiny wear-causing contaminants, including dirt, dust, sand, metal shards and other elements.
What does a roller bearing do?
A rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two bearing rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding.
Which of the following can lead to premature failure of roller bearings?
1) Lubrication and Contamination Lubricate the bearing too little, and the lubrication can become contaminated and cause excessive wear and possibly heat up, which will lead to premature bearing failure. Lubricating too much can cause a bearing to overheat, but only when the speeds are high.