Causes of arcing include static electricity from charged belts or processes that use calendar rolls, faulty wiring, improper grounding, welding, inadequate or defective insulation, loose rotor windings on an electric motor and short circuits.

This photo, taken with a microscope, shows a debris contamination bruise on a bearing race. A corresponding surface map of the dent is shown to the right.

NOTE Do not use excessive force when mounting or dismounting the unit. Follow all tolerance, t, and torque recommendations. Always follow the Original Equipment Manufacturer’s installation and maintenance guidelines. Ensure proper alignment. Never weld housed units. Do not heat components with an open ame. Do not operate at bearing temperatures above 121 ̊ C (250 ̊ F).

Wheel hubbearing

Deection, inaccurate machining or wear of bearing seats caused an irregular roller path on this tapered roller bearing outer ring.

Prepare an inspection sheet to capture all your observations. Take photographs throughout the procedure to help document or describe the damaged components.

Inspect other machine elements, especially the position and condition of components adjacent to the bearing, including locknuts, adapters, seals and seal wear rings.

It’s important that the right lubricant amount, type, grade, supply system, viscosity and additives are properly engineered for each bearing system. Base your selection on history, loading, speeds, sealing systems, service conditions and expected life. Without proper consideration of these factors, you may experience less-than- expected-bearing and application performance.

In conclusion, bearings are indispensable components in automotive systems, playing a pivotal role in supporting and facilitating the movement of various parts. The diverse range of bearings tailored for specific purposes ensures optimal performance and durability in different applications within vehicles. From the widely used ball bearings in wheel hubs and alternators to the robust roller bearings handling heavy loads in transmissions and differentials, each type contributes to the overall efficiency and reliability of automotive systems.

Wheel bearings

Advanced spalling initiated at water etch marks on the outer ring race makes this bearing unsuitable for further service.

Many different factors can cause bearing damage. Those listed in this guide are the most commonly identied types and causes of damage for anti-friction bearings, including cylindrical, spherical, tapered and ball designs. Always follow proper bearing maintenance and handling practices to help ensure your bearings achieve optimal performance levels.

In some cases, the cause is contact fatigue (inclusion origin, point surface origin, geometric stress concentration and micro-spalling). In 90 percent of the cases, the cause is non-fatigue factors, including:

Electric arc pitting or small burns, magnied 10X here, were created by arcs from improper electric grounding while the bearing was stationary.

A worn-out housing caused this bearing to lose t and fret (move) during service. As a result, metal tearing and wear occurred on this spherical outer ring.

If misalignment exceeds those limits, the load on the bearing won’t be distributed along the rolling elements and races as intended. Instead, it will be concentrated on only a portion of the rollers or balls and races. In cases of extreme misalignment or off angle, the load will be carried only on the extreme ends of the rolling elements and races.

Timken analyzes bearings from operations across the world. Our bearing service and repair specialists nd that 50 percent of the bearings submitted to us haven’t reached their calculated lives.

Tapered roller spaced nicking was caused by the roller edges hitting the race during installation. These nicks/dents have raised edges that can lead to excessive noise, vibration or act as points of stress concentration.

Proper maintenance and handling procedures are critical. Always follow installation instructions and maintain proper lubrication. Never spin a bearing with compressed air. The rollers may be forcefully expelled. Overheated bearings can ignite explosive atmospheres. Special care must be taken to properly select, install, maintain, and lubricate bearings that are used in or near atmospheres that may contain explosive levels of combustible gases or accumulations of dust such as from grain, coal, or other combustible materials. Consult your equipment designer or supplier for installation and maintenance instructions. If hammer and bar are used for installation or removal of a part, use a mild steel bar (e., 1010 or 1020 grade). Mild steel bars are less likely to cause release of high-speed fragments from the hammer, bar or the part being removed.

An undersized shaft or an outer ring that cannot be aligned due to the housing may cause a broken cam, a misaligned travel path or bearing wobble.

This outer ring has heavy corrosion on the race. This type of corrosion may only be a surface stain without pitting. If the staining can be cleaned with a ne emery cloth or crocus cloth, the bearing may be reused. If there are pits that cannot be cleaned with light polishing, the bearing should either be discarded or, if practical, refurbished.

With broad and deep expertise in material science and tribology, we’ve developed this guide to help you identify and analyze bearing damage, including possible causes and preventative courses of action.

Roller bearings also exhibit false brinelling when they’re used in positions that encounter very small reversing angular oscillation (less than one complete rotation of the rolling element).

Magnied 10X, this uting, dened as a series of small axial burns, was caused by an electric current passing through the bearing while it was rotating.

Clean parts and record the manufacturers’ information from markings on the bearing rings (part number, serial number, date code).

This type of bearing damage may be prevented by using the correct size shaft and by using the Timken self-aligning feature, a spherical outer ring to compensate for initial misalignment and correctly mount bearings.

The damage caused by inadequate lubrication varies greatly in both appearance and performance. Depending on the level of damage, it may range from very light heat discoloration to total bearing lockup with extreme metal ow.

Tensile stresses can be very high in tightly fitted bearing components. Attempting to remove such components by cutting the inner rings may result in a sudden shattering of the component causing fragments of metal to be forcefully expelled. Always use properly guarded presses of bearing pullers to remove bearings from shafts, and always use suitable personal protective equipment, including safety glasses.

The marks visible on the outside diameter of this outer ring are caused by a high spot on the housing. The outer ring race was found spalled at the location that corresponds to the outer ring mark from heavy contact with the housing high spot.

Wear caused by vibration or relative axial movement between the rollers and races is depicted in this tapered roller bearing outer ring.

Careful inspection of all bearings, gears, seals, lubricants and surrounding parts may help determine the primary cause of damage.

wheel bearing中文

Classic fretting corrosion from poor tting practice is depicted here. Relative movement under load between the bearing and its seat caused this worn and corroded condition.

Etching is typically caused by condensate collecting in the bearing housing from temperature changes. Moisture or water can get in through damaged, worn or inadequate seals. Improperly washing and drying bearings when you remove them for inspection also can cause considerable damage. After cleaning and drying or preparing bearings for storage, coat them with oil or another preservative and wrap them in protective paper. Always store bearings, new or used, in a dry area and keep them in their original packaging to reduce the risk of static corrosion appearing before mounting.

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Common external debris contaminants include dirt, sand and environmental particles. Typical causes of internal debris contamination include wear from gears, splines, seals, clutches, brakes, joints, improperly cleaned housings, and damaged or spalled components. These hard particles travel within the lubrication, through the bearing and eventually bruise (dent) the surfaces. Raised metal around the dents acts as surface-stress risers to cause premature spalling and reduce bearing life.

Scalloping marks in the outer ring are common with excessive endplay. This occurs when unloaded rollers enter the small load zone and are suddenly exposed to heavy loads.

Cracked outer ring in a wheel hub. The outer ring turns and wears the outer ring seat so the t becomes more loose. Then the outer ring starts to stretch or roll out. Wear and stretching continues to the point where the metal reaches its breaking point and the outer ring cracks open.

In mild cases, the discoloration is from the lubricant staining the bearing surfaces. In severe cases, the metal is discolored from high heat.

Wheelbearingreplacement cost

This spherical roller bearing inner race depicts a fractured small rib caused by the use of improper installation tools.

Extract any used lubricant samples from bearings, housing and seal areas to determine lubricant conditions. Package it separately and label it properly.

In general, you should apply the rotating bearing race with a press or tight t. An example is a wheel hub, where the outer race should be applied with a press t. The races on a stationary axle would normally be applied with a light or loose t. Where the shaft rotates, the inner race should normally be applied with a press t and the outer race may be applied with a split t or even a loose t, depending on the application.

DISCLAIMER This guide is provided solely to give you analysis tools and data to assist you in your product selection. Product performance is affected by many factors beyond the control of Timken. Therefore, you must validate the suitability and feasibility of all product selections for your applications. Timken products are sold subject to Timken terms and conditions of sale, which include our limited warranty and remedy. You can nd these at timken/termsandconditionsofsale. Please consult with your Timken engineer for more information and assistance. Every reasonable effort has been made to ensure the accuracy of the information in this writing, but no liability is accepted for errors, omissions or for any other reason.

Check the bearing environment for external inuences, like other equipment problems, that preceded or occurred at the same time bearing damage was reported.

The careful selection and integration of these diverse bearing types contribute to the overall reliability, efficiency, and safety of automotive vehicles. As technology advances, continuous innovations in bearing design and materials will likely further optimize automotive performance, meeting the evolving demands of the industry and enhancing the driving experience for users.

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Debris from other fatigued parts, inadequate sealing or poor maintenance caused bruising on this tapered roller bearing race.

Bearings play a crucial role in automotive applications, providing support and facilitating the movement of various components. There are several types of bearings used in automotive systems, each designed for specific purposes. Here are seven common types: Ball bearings Roller bearings Needle bearings Thrust Spherical Plain bearings/Bushings Angular contact bearings 1. Ball Bearings: Function: Ball bearings consist of small, spherical rolling elements (balls) held in a ring. They reduce friction between rotating surfaces, allowing smooth and efficient motion. Automotive Applications: Wheel bearings are a common application in vehicles. They support the rotating hub and allow smooth wheel movement. Ball bearings are also used in alternators and gearboxes due to their ability to handle high-speed rotation. 2. Roller Bearings: Function: Roller bearings use cylindrical or tapered rollers instead of balls. The rollers distribute the load over a larger surface area, enabling them to handle heavier radial and axial loads compared to ball bearings. This design reduces friction and provides increased durability. Automotive Applications: Tapered roller bearings are commonly employed in wheel hubs, where they support the vehicle's weight and handle the forces associated with acceleration and deceleration. They are also used in differentials and transmissions, where high loads and durability are crucial. Also Read: Driving Efficiency: A Comprehensive Guide to Automotive Bearings  3.  Needle Bearings: Function: Needle bearings serve the purpose of handling high radial loads in situations with restricted space due to their thin, cylindrical rollers featuring a high length-to-diameter ratio. Automotive Applications: Renowned for their efficiency and capacity to endure substantial loads, these bearings find common application in automotive components like gearbox shafts and connecting rods, particularly in instances where space limitations are a significant consideration. 4. Thrust Bearings: Function: Thrust bearings are designed to accommodate axial loads, preventing movement along the axis of rotation. They come in various types, including ball thrust bearings and roller thrust bearings, each optimized for specific load and speed conditions. Automotive Applications: Clutch release bearings are a common example of thrust bearings in automotive systems. They facilitate smooth engagement and disengagement of the clutch by handling the axial loads associated with these operations. 5. Spherical Bearings: Function: Spherical bearings facilitate misalignment and angular movement owing to their spherical inner and outer rings. This adaptability is particularly beneficial in scenarios where components may undergo diverse angles of motion. Automotive Applications: In the automotive realm, spherical bearings are commonly employed in suspension components like control arms and strut mounts. Their presence allows the suspension system to absorb shocks and vibrations while accommodating movement in various directions. 6. Plain Bearings (Bushings): Function: Plain bearings, commonly referred to as bushings, provide a sliding surface between two components to reduce friction. Unlike rolling element bearings, plain bearings operate with a sliding motion. They consist of a cylindrical sleeve, often made of materials like bronze or polymer that fits around a shaft. Automotive Applications: Plain bearings are used in various automotive applications where sliding motion is necessary. For instance, they are commonly found in suspension systems, providing a low-friction interface between moving components like control arms and sway bars. Engine connecting rod bushings and various pivot points in the vehicle's chassis also utilize plain bearings. 7. Angular Contact Bearings: Function: Angular contact bearings are designed to handle both radial and axial loads by placing the load at an angle to the bearing axis. This configuration allows for increased load-carrying capacity compared to standard ball bearings. Automotive Applications: Angular contact bearings find applications in scenarios where both radial and axial loads are present, such as in front wheel hub assemblies. In these assemblies, the bearing accommodates the weight of the vehicle (radial load) as well as the lateral forces experienced during cornering (axial load). This design enhances the overall stability and performance of the wheel assembly. Conclusion: In conclusion, bearings are indispensable components in automotive systems, playing a pivotal role in supporting and facilitating the movement of various parts. The diverse range of bearings tailored for specific purposes ensures optimal performance and durability in different applications within vehicles. From the widely used ball bearings in wheel hubs and alternators to the robust roller bearings handling heavy loads in transmissions and differentials, each type contributes to the overall efficiency and reliability of automotive systems. Needle bearings, with their compact design and high load-bearing capacity, find a niche in transmission components, addressing space constraints. Thrust bearings, exemplified by clutch release bearings, manage axial loads, ensuring smooth engagement and disengagement of the clutch. Spherical bearings offer flexibility in suspension systems, accommodating varying angles of motion and enhancing shock absorption. Plain bearings or bushings, operating with a sliding motion, play a crucial role in reducing friction in suspension systems and engine components. Lastly, angular contact bearings provide a solution for scenarios where both radial and axial loads are present, enhancing stability and performance in front wheel hub assemblies. The careful selection and integration of these diverse bearing types contribute to the overall reliability, efficiency, and safety of automotive vehicles. As technology advances, continuous innovations in bearing design and materials will likely further optimize automotive performance, meeting the evolving demands of the industry and enhancing the driving experience for users.

Plain bearings or bushings, operating with a sliding motion, play a crucial role in reducing friction in suspension systems and engine components. Lastly, angular contact bearings provide a solution for scenarios where both radial and axial loads are present, enhancing stability and performance in front wheel hub assemblies.

You can distinguish false brinelling from true brinelling by examining the depression or wear area. False brinelling will actually wear away the surface texture, whereas the original surface texture will remain in the depression of a true brinell.

Each time the current is broken while passing between the ball or roller and race, it produces a pit on both parts. Eventually uting develops. As it becomes deeper, it creates noise and vibration. A high-amperage current, such as a partial short circuit, will cause a rough, granular appearance. Heavy jolts of high-amperage charges will cause more severe damage, welding metal from the race to the ball or roller. These metal protrusions on the roller will, in turn, cause a crater effect in the race, generating more noise and vibration.

Gather operating data from bearing monitoring devices; analyze service and maintenance records and charts; and secure application diagrams, graphics or engineering drawings.

Follow the steps below for an accurate and complete analysis when investigating any bearing damage or system breakdowns. If you need help, contact one of our sales or service engineers.

Bearings play a crucial role in automotive applications, providing support and facilitating the movement of various components. There are several types of bearings used in automotive systems, each designed for specific purposes. Here are seven common types:

External debris contamination rolling through the bearing may cause pitting and bruising of the rolling elements and races.

Level 2 – Micro-spalling or peeling results from thin lubricant lm due to high loads/low speed or elevated temperatures.

Needle bearings, with their compact design and high load-bearing capacity, find a niche in transmission components, addressing space constraints. Thrust bearings, exemplified by clutch release bearings, manage axial loads, ensuring smooth engagement and disengagement of the clutch. Spherical bearings offer flexibility in suspension systems, accommodating varying angles of motion and enhancing shock absorption.

If you have bearing damage beyond the scope of this guide, contact our service engineering team. We can work with you – often on-site – to get to the root cause of your problems. We also offer in-depth training that’s customized to your specic industry or application.

Secure a sample of new, unused lubricant. Record any specication or batch information from the container. Obtain the technical specications and any related material safety data (handling, disposal, toxicological) documentation to accompany lubricant shipments.