What are bearings used forin a car

Your timing belt synchronizes the rotation of key engine components like the camshaft and crankshaft. It ensures the valves open and close at exactly the right time to allow fuel and air into the combustion chamber. If your timing belt breaks, the piston and valves can collide, causing serious engine damage.

Types ofbearingsand their applications

Listen for squealing noises that may indicate issues like belt slippage or misalignment. Some noise is normal, but loud squealing that starts and stops with engine speed is a red flag. Have your timing belt inspected right away.

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]

3 main types ofbearings

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]

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]

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.

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.

Whatis bearing

Every 30,000 miles or so, have a technician inspect your belt’s condition during routine maintenance. They can spot signs of wear and determine if replacement is needed sooner than the manufacturer’s recommendation. An ounce of prevention can save you an engine overhaul down the road.

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]

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]

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]

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]

Look under your hood and below your vehicle for oil leaks. If oil leaks onto your timing belt, it can cause the rubber to swell, degrade, and eventually fail. Identify the source of any oil leaks, address them, and replace the belt.

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]

Types ofbearingspdf

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.

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]

Most manufacturers recommend replacing your timing belt at 60,000 to 90,000 miles. But there are other signs that indicate you should replace it sooner:

While it may be out of sight and out of mind, the timing belt on your vehicle is an important component. And if yours fails, you may find yourself stranded on the side of the road at an inopportune moment. Familiarizing yourself with these warning signs and bringing your vehicle to a professional if you notice them can help you avoid expensive repairs. If you notice one or more of these signs and you’re in the greater Houston, TX area, stop by Chimney Rock Care. We would love to help you. Call us at 346-369-7477 to schedule a service appointment.

8 types of bearing

When components like water pumps, tensioners, and pulleys fail, they can also take the timing belt out. If you need to replace any of these parts, go ahead and do the timing belt simultaneously, even if it looks fine. The additional labor to replace it now is minor compared to doing it later.

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]

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]

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]

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.

If you’re like most drivers, you don’t give much thought to your vehicle’s timing belt until something goes wrong. But this small part plays a crucial role in keeping your engine running smoothly. Knowing when to replace your timing belt can help you avoid more costly repairs down the road. Here are some of the key warning signs that your timing belt may be nearing the end of its lifespan.

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]

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]

Bearing definition engineering

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]

Consistency is key for proper engine operation. Misfires that cause occasional power loss or rough idling can indicate timing issues and belt wear. It may not yet be broken, but a worn belt that’s slipping can produce similar symptoms.

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.

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.

Modern vehicles have sensors that detect issues with timing and set diagnostic trouble codes when problems are detected. Pay attention to any check engine lights that come on, especially ones indicating cylinder misfires or camshaft/crankshaft correlation errors.

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.

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]

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]

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

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]

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]

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.

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 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.

Types of bearing with diagram

Inspect your timing belt periodically for damage like cracked teeth or exposed cords. Also, look for signs of wear, like glazing or dirt buildup. If you notice any visible issues, don’t wait to replace it. The belt could fail at any time.

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]

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.

Check service records to see if the timing belt has been replaced before. If you find no evidence of it being done already, err on the side of caution once you pass 60,000 miles. Replacing it now, instead of finding out the hard way that it already had 90,000 miles on it, will give you peace of mind.

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

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]

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.

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]

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]

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]