Axial or radial play in the wheel or wheel hub. Should the wheel hub move up and down or in and out, the bearing may be worn.

A sideways torque on a radial bearing also applies pressure to the cage that holds the rolling elements at equal distances, due to the rolling elements trying to all slide together at the location of highest sideways torque. If the cage collapses or breaks apart, the rolling elements group together, the inner ring loses support, and may pop out of the center.

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If a sideways torque is applied to a deep groove radial bearing, an uneven force in the shape of an ellipse is applied on the outer ring by the rolling elements, concentrating in two regions on opposite sides of the outer ring. If the outer ring is not strong enough, or if it is not sufficiently braced by the supporting structure, the outer ring will deform into an oval shape from the sideways torque stress, until the gap is large enough for the rolling elements to escape. The inner ring then pops out and the bearing structurally collapses.

If the bearing is used under oscillation, oil lubrication should be preferred.[8] If grease lubrication is necessary, the composition should be adapted to the parameters that occur. Greases with a high bleeding rate and low base oil viscosity should be preferred if possible.[9]

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.

On average, the cost for a Ford Fusion Wheel Bearings Replacement is $205 with $65 for parts and $140 for labor. Prices may vary depending on your location.

Growling or grinding noise from a wheel. Failed or failing wheel bearings make a very characteristic growling noise which will grow louder as the bearing wear progresses. If you believe the wheel bearing noise is coming from one side of the car, you can self-diagnosis your wheel bearing as you drive the car by loading and unloading vehicle weight You can do this by “swerving” from side-to-side. For example, if the noise markedly increases when you swerve to left, which shifts the vehicle’s weight to the right, then it often indicates the wheel bearing on the right is failing.

If the viscosity of lubricant is higher than recommended, lifespan of bearing increases, roughly proportional to square root of viscosity. If the viscosity of the lubricant is lower than recommended, the lifespan of the bearing decreases, and by how much depends on which type of oil being used. For oils with EP ('extreme pressure') additives, the lifespan is proportional to the square root of dynamic viscosity, just as it was for too high viscosity, while for ordinary oils lifespan is proportional to the square of the viscosity if a lower-than-recommended viscosity is used.[7]

A wheel bearing assembly consists of rolling elements, such as hardened steel ball bearings or roller bearings, that roll on and around hardened steel bearing races. The wheel bearings support the front and rear axle, and all the weight of your car. Wheel bearings are made with a high-precision technique using extremely hard steel in order to withstand all the normal impacts that occur to the wheel and tire assembly as you drive along the road.

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Although bearings had been developed since ancient times, the first modern recorded patent on ball bearings was awarded to Philip Vaughan, a Welsh inventor and ironmaster who created the first design for a ball bearing in Carmarthen in 1794. His was the first modern ball-bearing design, with the ball running along a groove in the axle assembly.[1]

In general, ball bearings are used in most applications that involve moving parts. Some of these applications have specific features and requirements:

Fittings that are not allowed to slip are made to diameters that prevent slipping and consequently the mating surfaces cannot be brought into position without force. For small bearings this is best done with a press because tapping with a hammer damages both bearing and shaft, while for large bearings the necessary forces are so great that there is no alternative to heating one part before fitting, so that thermal expansion allows a temporary sliding fit.[7]

Jules Suriray, a Parisian bicycle mechanic, designed the first radial style ball bearing in 1869,[2] which was then fitted to the winning bicycle ridden by James Moore in the world's first bicycle road race, Paris-Rouen, in November 1869.[3]

For single-row deep-groove ball bearings, SKF's documentation says that maximum axial load is circa 50% of maximum radial load, but it also says that "light" and/or "small" bearings can take axial loads that are 25% of maximum radial load.[7]

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If both axial and radial loads are present, they can be added vectorially, to result in the total load on bearing, which in combination with nominal maximum load can be used to predict lifespan.[7] However, in order to correctly predict the rating life of ball bearings the ISO/TS 16281 should be used with the help of a calculation software.

The calculated life for a bearing is based on the load it carries and its operating speed. The industry standard usable bearing lifespan is inversely proportional to the bearing load cubed.[citation needed] Nominal maximum load of a bearing, is for a lifespan of 1 million rotations, which at 50 Hz (i.e., 3000 RPM) is a lifespan of 5.5 working hours. 90% of bearings of that type have at least that lifespan, and 50% of bearings have a lifespan at least 5 times as long.[7]

For single-row edge-contact ball bearings, axial load can be about 2 times max radial load, and for cone-bearings maximum axial load is between 1 and 2 times maximum radial load.[7]

If an axle has two bearings, and temperature varies, axle shrinks or expands, therefore it is not admissible for both bearings to be fixed on both their sides, since expansion of axle would exert axial forces that would destroy these bearings. Therefore, at least one of the bearings must be able to slide.[7]

Vibration in the steering wheel or vehicle body and/or wandering. Vibration and lack of directional stability could be consequences of loose or worn out wheel bearings.

Common ball bearing designs include angular contact, axial, deep-groove, and preloaded pairs. The balls in ball bearings can also be configured in various ways. Ball bearings are used in a wide range of applications, some of which include skateboards and centrifugal pumps.

30 weightball bearings

Lubrication can be done with a grease, which has advantages that grease is normally held within the bearing releasing the lubricant oil as it is compressed by the balls. It provides a protective barrier for the bearing metal from the environment, but has disadvantages that this grease must be replaced periodically, and maximum load of bearing decreases (because if bearing gets too warm, grease melts and runs out of bearing). Time between grease replacements decreases very strongly with diameter of bearing: for a 40 mm bearing, grease should be replaced every 5000 working hours, while for a 100 mm bearing it should be replaced every 500 working hours.[7]

Bearings can withstand their maximum load only if the mating parts are properly sized. Bearing manufacturers supply tolerances for the fit of the shaft and the housing so that this can be achieved. The material and hardness may also be specified.[7]

The recommended dynamic viscosity decreases with rotating frequency. As a rough indication: for less than 3000 RPM, recommended viscosity increases with factor 6 for a factor 10 decrease in speed, and for more than 3000 RPM, recommended viscosity decreases with factor 3 for a factor 10 increase in speed.[7]

The part of a bearing that rotates (either axle hole or outer circumference) must be fixed, while for a part that does not rotate this is not necessary (so it can be allowed to slide). If a bearing is loaded axially, both sides must be fixed.[7]

Bearings have static load ratings. These are based on not exceeding a certain amount of plastic deformation in the raceway. These ratings may be exceeded by a large amount for certain applications.

If a bearing is rotating, but experiences heavy load that lasts shorter than one revolution, static max load must be used in computations, since the bearing does not rotate during the maximum load.[7]

For a bearing to have its nominal lifespan at its nominal maximum load, it must be lubricated with a lubricant (oil or grease) that has at least the minimum dynamic viscosity (usually denoted with the Greek letter ν {\displaystyle \nu } ) recommended for that bearing.[7]

Also, if a bearing is not rotating, oscillating forces on the bearing can cause impact damage to the bearing race or the rolling elements, known as brinelling. A second lesser form called false brinelling occurs if the bearing only rotates across a short arc and pushes lubricant out away from the rolling elements.

Note that dynamic viscosity of oil varies strongly with temperature: a temperature increase of 50–70 °C causes the viscosity to decrease by factor 10.[7]

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The complexity of wheel bearing replacement varies greatly depending on the vehicle make, model, year, the wheel position (front versus rear), and the drive type (AWD versus FWD):

Lubrication can also be done with an oil, which has advantage of higher maximum load, but needs some way to keep oil in bearing, as it normally tends to run out of it. For oil lubrication it is recommended that for applications where oil does not become warmer than 50 °C, oil should be replaced once a year, while for applications where oil does not become warmer than 100 °C, oil should be replaced 4 times per year. For car engines, oil becomes 100 °C but the engine has an oil filter to maintain oil quality; therefore, the oil is usually changed less frequently than the oil in bearings.[7]

A 'freely sliding fit' is one where there is at least a 4 μm clearance, presumably because surface-roughness of a surface made on a lathe is normally between 1.6 and 3.2 μm.[7]

The ball size increases as the series increases, for any given inner diameter or outer diameter (not both). The larger the ball the greater the load carrying capacity. Series 200 and 300 are the most common.[4]

For a bearing to operate properly, it needs to be lubricated. In most cases the lubricant is based on elastohydrodynamic effect (by oil or grease) but working at extreme temperatures dry lubricated bearings are also available.

For a bearing where average of outer diameter of bearing and diameter of axle hole is 50 mm, and that is rotating at 3000 RPM, recommended dynamic viscosity is 12 mm2/s.[7]

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If a bearing is not rotating, maximum load is determined by force that causes plastic deformation of elements or raceways. The indentations caused by the elements can concentrate stresses and generate cracks at the components. Maximum load for not or very slowly rotating bearings is called "static" maximum load.[7]

In general, maximum load on a ball bearing is proportional to outer diameter of the bearing times the width of the bearing (where width is measured in direction of axle).[7]

Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races.

All ball BearingsElden Ring

The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling, they have a much lower coefficient of friction than if two flat surfaces were sliding against each other.

Most bearings are meant for supporting loads perpendicular to axle ("radial loads"). Whether they can also bear axial loads, and if so, how much, depends on the type of bearing. Thrust bearings (commonly found on lazy susans) are specifically designed for axial loads.[7]

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If a shaft is supported by two bearings, and the center-lines of rotation of these bearings are not the same, then large forces are exerted on the bearing, which may destroy it. Some very small amount of misalignment is acceptable, and how much depends on type of bearing. For bearings that are specifically made to be 'self-aligning', acceptable misalignment is between 1.5 and 3 degrees of arc. Bearings that are not designed to be self-aligning can accept misalignment of only 2–10 minutes of arc (0.033-0.166 degrees) .[7]

Tire and wheel assembly does not turn smoothly. With the wheel jacked up, and the car not in gear, the wheel should rotate smoothly. Rough or inconsistent movement, which is often accompanied by noise, can signify damaged bearings. Be sure the brakes are not dragging as you perform this check.

No. Wheel bearing failure is usually gradual, although in some cases it starts immediately after the dramatic impact of the wheel and tire assembly with a deep pothole. Wheel bearings can sometimes make noise for quite some time before you experience a catastrophic failure that would result in complete separation of the wheel and tire assembly from the axle. Generally, the risk of sudden failure increases with the noise level. But strictly speaking, once the bearing has started to fail it is impossible to predict exactly when it will fail completely. So it should not continue to be driven. Were a failing bearing to seize or break while you are moving, you could experience loss of control of the vehicle. Once you receive a conclusive diagnostic that a wheel bearing has failed, replace the bearing promptly.

There are several common designs of ball bearing, each offering various performance trade-offs. They can be made from many different materials, including stainless steel, chrome steel, and ceramic (silicon nitride, Si3N4). A hybrid ball bearing is a bearing with ceramic balls and metal races.

The industry standard life calculation is based upon the work of Lundberg and Palmgren performed in 1947. The formula assumes the life to be limited by metal fatigue and that the life distribution can be described by a Weibull distribution. Many variations of the formula exist that include factors for material properties, lubrication, and loading. Factoring for loading may be viewed as a tacit admission that modern materials demonstrate a different relationship between load and life than Lundberg and Palmgren determined .[7]

Often Conrad-style ball bearings will exhibit contact ellipse truncation under axial load. That means that either the ID of the outer ring is large enough, or the OD of the inner ring is small enough, so as to reduce the area of contact between the balls and raceway. When this is the case, it can significantly increase the stresses in the bearing, often invalidating rules of thumb regarding relationships between radial and axial load capacity. With construction types other than Conrad, one can further decrease the outer ring ID and increase the inner ring OD to guard against this.