Anti-Friction bearings

The main purpose of these bearings is to minimize the friction in bearing. Due to this reason, the speed of an object increases and friction and temperature decreases. Such bearing have long life. These bearing also sub-divided into following categories.

 (A.)Ball bearings:

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A ball bearing is a rolling element bearing that used ball to maintain the separation between the bearing races. The width of these bearing is smaller than the bore diameter or ball. On the basis of load and groove cut, ball bearings are classified in the following types.

 (a.)Single row ball bearings:

These bearing have only one groove cut in outer and inner rings with the ball in identical line.

 (b.)Double row ball bearing:

These bearing have two grooves cut in inner and outer ring lie in two rows of the bearing.

(c.)Self-aligning ball bearings:

These bearings can withstand with journal loads. These loads are generally inclined due to shaft misalignment. These types of bearings have a spherical bore on the outer race.

These bearings are designed to take an axial thrust as well as radial loads.

(d.)Angular contact ball bearings:

These bearings are designed to take an axial thrust as well as radial loads.

 (e.)Thrust ball bearings:

These bearings are useful for taking vertical thrust load but cannot take any radial load. Some special thrust bearings are available which can also take horizontal end thrust.

(F.)Roller bearings:

Roller bearings are available with the grooved race in the outer and inner members. Roller bearings are capable of carrying the journal (radial) loads. It can work with greater load than ball bearings. To use this bearing, race is required to be locked. On the basis of uses, roller bearings are classified in following types.

 (G.)Self-aligning roller bearings:

These bearings are self-adjustable and it is not affected by non-centering of shaft deformation flexure of shaft and bearing block, so it can compensate the concentricity error caused by these reason.

 (H.)Tapered roller bearings:

These bearings are used to take thrust only one direction. For opposing thrust, the bearings must be mounted in opposite pair. Tapered roller bearings are mainly used for high axial thrust loads.

(I.)Needle roller bearings:

These types of bearings have very small roller diameter. Rolling element is called needle roller. Needle roller bearings are used where the outside diameter of bearing restricted due to limited bearing space in the housing. The needles fitted in a circular cage which is push-fit in its housing.

 (J.)Cylindrical roller bearings:

These bearings are used in such places, where more load is to be bear. These are made of hollow cylindrical roller.

(K.)Barrel roller bearings:

The roller fitted in this type of bearing has barrel shape. Its diameter up to full length is uneven. These bearings are self-alignment type bearing, so due to this reason, it has no difficulty to maintain shaft in straight line.

(L.)Spherical roller bearings:

These bearings are used in such places, where chance of angular condition in shaft may be possible. In these bearings, rollers are fitted in ball cage in such a way that in angular condition, in inner and outer race, the energy transfer can be possible in full capacity.

Advantages and disadvantages of anti-friction bearings:

Advantages:

• Special shielded bearing does not required lubrication again.
• It is easy to replace.
• It has very long life and has very less friction.
• It easy operates on high speed and required less lubrication.

Disadvantages:

• Initial cost is usually high.
• Greater diameter space required for comparable shaft diameter.
• Dirt, metal chips and so on, entering the bearings can limit their life causing early failure.
• Lesser capacity to withstand shock