User Profile

asdfaas44

What's the Difference Between Bearings?

Bearings are used to help reduce friction.

Metal-upon-metal contact produces large amounts of friction. The friction adds to wear

and tear of the metal, producing grinding that slowly degrades the metal. Bearings

reduce friction by having the two surfaces roll over each other, reducing the amount of

friction produced. They consist of a smooth metal ball or roller that rolls against a

smooth inner and outer metal surface. The rollers or balls take the load, allowing the

device to spin.

The load acted upon a bearing is either a radial or thrust load. Depending on the

location of the bearing in the mechanism, it can see all of a radial or thrust load or a

combination of both. For example, the bearing in the wheel of your car supports a radial

and a thrust load. The weight of the car on the bearing produces a radial load while the

thrust load is produced as the car turns a corner. Here we will examine some types of

common bearings.

Ball Bearings

Ball bearings are most common type of bearing and can handle both radial and thrust

loads. Ball bearings are also known as deep-groove single-row or Conrad bearings. The

inner ring is typically fastened to the rotating shaft and the groove on the outer

diameter provides a circular ball raceway. The outer ring is mounted onto the bearing

housing. The ball bearings are housed in a race and when the load is applied, it is

transmitted from the outer race to the ball and from the ball to the inner race. The

raceway grooves have typical curvature radii of 51.5% to 53% of the ball diameter.

Smaller curvature raceways can cause high rolling friction due to the tight conformity

of the balls and raceways. Higher curvature raceways can shorten fatigue life from

increased stress in the smaller ball-race contract area.

1. Ball bearings, also known as Conrad bearings, are typically used in small load

applications.

The contact points between the ball and the outer race is very small due to the

spherical shape of the bearing. This also helps the ball spin very smoothly. Since the

contact point is so small, the flanged

bearing
can become overloaded at a specific point causing the ball bearing to

become deformed. This will ruin the bearing. Ball bearings are typically used in

applications where the load is relatively small.

2. The table above lists some general types of ball bearings and their typical load

capabilities.

Straight

Roller Bearings


Straight roller or cylindrical bearings run in cylindrical raceways and have low-

friction, high-radial load capacity, and high speed capability.

Roller bearings are cylinder-

shaped stainless bearings where

the point of contact between the bearing and the race is a line rather than a point.

Load is distributed over a larger area and allows the bearing to handle a greater load.

To minimize its tendency to skew, the roller’s length is not much greater than the

diameter of the roller.

3. Straight or cylindrical roller bearings can be found in applications like

conveyor-belt rollers, which are required to hold heavy radial loads.

Their usual design is free to float axially, and they have roller-guiding flanges on

both sides of one ring and none on the other side. This allows for the bearing to expand

due to thermal activity when used in combination with a ball

miniature bearing’s fixed

location at the opposite end. A thrust load can be supported in one direction if a

guiding flange is added on one of the opposing rings’ side. A second flange can be

added for two-directional thrust capacity.

Tapered Roller Bearings

4. Tapered roller bearings are designed to withstand a radial and thrust load, and

can be found in car hubs due to the amount of radial and thrust loads they can carry.

In a tapered roller bearing, the rings and the rollers are tapered in the shape of

truncated cones to simultaneously support axial and radial loads. The ratio of the loads

depends on the angle of the axes between the roller and bearing. The greater the angle

is the greater axial load can be supported. The contact angle for most tapered roller

bearings range is between 10 to 16 degrees. For higher thrust-load capacity, a 30-degree

contact angle is used.

5. Tapered bearings are mounted pairs since they handle radial loads better than a

single row of tapered small size

bearings
. For heavy-duty applications, two or four rows of tapered rollers are

combined in a single unit in large bearings.

Spherical Roller Bearings

Spherical roller bearings typically consist of two rows of barrel-shaped rollers

running in two raceways. One is on the inner ring and the other is on a continuous

spherical surface ground on the inner diameter of the outer ring. This allows the

bearing to operate with some misalignment. Spherical rollers have barrel profiles that

closely match the raceways profiles, hence making them robust and having a high load

capacity. They are mounted in pairs inside the large size bearing housing and are faced in opposite directions.

This is done so that the load can be supported in either direction.

Needle Roller Bearings

Needle roller bearings use elongated cylindrical rolling elements with small

diameters. They are used in applications where radial space is limited. The diameter to

length ratio for the needles varies between 1-to-2.5 and 1-to-10. Due to their small

size, they cannot be guided accurately and generate high amounts of friction. They are

used at low speeds and oscillating motions as a result. Cages may be used to help guide

the needles and improve retention.

Thrust Bearings

Designed to handle high thrust loads, roller-thrust bearings are typically found in

gearsets used for car transmissions between gears or between the housing and rotating

shafts. The angled teeth found in helical gears used in car transmissions produce a high

thrust load that is supported by the roller-thrust bearings. Roller-thrust bearings

slide within a roller-race contact to handle the surface-speed variation that comes as a

result of the varying diameter across the contact zone.

8. Ball-thrust bearings are designed to handle almost exclusively thrust loads in

low-speed, low-weight applications. An example of its use would be in bar stools where

they are used to support the seat.

Ball-thrust bearings are comprised of two grooved plates with a set of balls between

them. The ball-race contacts have a sliding action that is increased at high speeds by

the centrifugal force on the balls. Cylindrical roller thrust

middle size bearings are

limited to about 20% of the speed of its radial bearing counterpart and ball-thrust

bearings are limited to 30% of the speed of their counterpart.
  • Létrehozva: 21-11-05
  • Utolsó belépés: 21-11-05

asdfaas44 hirdetések

Kedves Partnerünk!

Az elmúlt napokban jelentős technikai probléma akadályozta oldalunk megjelenését! A weboldal rendszerét újraindítottuk, így már akadálytalanul lehet használni. Kérjük, abban az esetben is regisztráljon újra, ha Önnek már volt korábban regisztrációja a Birizga oldalán, és adja fel továbbra is bátran hirdetéseit!
Ha tetszik az oldal, oszd meg ismerőseiddel is!

Web Powered by Yclas 2009 - 2021