Bearings allow smooth, low-friction motion between two surfaces. The motion can be either rotary (a shaft turning in a housing) or linear (one machine element moving across another). Bearings are widely used to support shafts and allow their free rotation. Load is applied to these bearings in either of two directions. Radial loads act a right angles to the shaft or bearing's axis of rotation. Axial, or thrust, loads are applied parallel to the axis of rotation.
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Click Here for the Glossary of Bearing Terms
Radial Ball Bearing |
Taper Bearing |
Needle Bearing |
Roller Bearing |
Thrust Ball Bearing |
Cylindrical Roller Bearing |
Angular Contact Bearing |
Spherical Bearing |
Linear Bearing |
Spherical Plain Bearing |
Specialty Bearing |
There are two basic types of radial ball bearings: the nonfilling-slot or Conrad type, and the filling-slot or maximum-capacity type. The non-filling-slot or Conrad bearing has a deep, uninterrupted raceway on the inner and outer rings. Its carries high radial loads plus moderate thrust loads in either direction.
A wide variety of equipment including appliances, machine tools, mobile equipment, turbines, and industrial machinery, employs tapered roller bearings in applications ranging from low to high-speed. Tapered bearings carry heavy radial loads, thrust loads, or both.
Though similar to cylindrical roller bearings, needle bearings have a much smaller diameter-to-length ratio. (The word 'needle' was originally used where the roller length was at least six times the diameter.) Though many do not require separators, needle bearings are available with separators for higher-speed applications. The separators control circumferential clearance between needles and keep the needles parallel to the shaft axis.
Because roller bearings have more rolling surface area in contact with inner and outer races, they generally support heavier loads than comparably sized ball bearings. Roller bearings, handle moderate to heavy loads and are capable of handling high-impact or shock loads. They exhibit less elastic deformation than ball bearings because contact stresses for rollers are lower.
Some applications are best served by thrust bearings, which carry primarily thrust loads and provide axial shaft location. These bearings differ from other types in that the space between rings is oriented perpendicular to the axis of rotation. A thrust ball bearing generally contains two races, either flat or grooved, separated by a ball-bearing retainer assembly.
Of the four types, cylindrical bearings have the highest radial load capacity and speed capability. A non-locating type of cylindrical bearing, enables axial movement of the inner and outer ring to accommodate both thermal and axial expansion of the shaft and tolerances in the assembly. Cylindrical bearings with shoulders on the inner and outer rings, accommodate some thrust loading, but this is limited by the amount of heat generated and dissipated.
The single-row(Right Picture), angular-contact bearing, accepts high thrust load in combination with moderate radial load. The ratio of thrust to radial load depends on the angle of the contact between the races and the bearing axis.
Available designs can handle thrust loads from 150% of the radial load to more than 300%. Bearings of this type are mounted singly, back to back, face to face, or in tandem.
Usually containing one or two rows of rollers within a spherical outer raceway, spherical roller bearings, support high rdial or combined radial and thrust loads. Because the outer raceway is spherical, these bearings are internally self-aligning, making them suitable for heavy-duty applications. They accommodate misalignment, usually from 0.5 deg to 2 deg, with no decrease in rating or life. A single-row type can be used to support a predominantly radial load.
- Ball Bearings: Perhaps the simplest type of rolling-element linear bearing in the linear ball bearing. A linear ball bearing has three or more oblong circuits of balls. Each circuit holds balls in one of its straight sides in rolling contact between the shaft and the bearing race. The load rolls along the balls in this part of the circuit. Balls in the rest of the circuit circulate freely within the sleeve clearance. A retainer guides the balls and keeps them from falling out if the bearing is removed from the shaft. Thus, the retainer makes the linear ball bearing as easy to handle and install as a plain bearing.
- Profile Rail Linear Guides: These consist of carriages, containing recirculating rolling elements, which ride on continuously supported rails. The basic operating principle of a profile rail linear guide is the same as that for a round rail ball bearing.
The Spherical Plain Bearing has a spherically shaped inner ring with ground cylindrical bore for shaft mounting. The cylindrical outer surface of the outer ring permits convenient mounting in a housing. These are some of the advantages of using the Spherical Plain Bearing:
- High Capacity
- Ability to accommadate misalignment
- Superior performance in low frequency oscillating
- Simplified housing and shaft design
- Easy installation
- Radial types of available with seals
We also distribute a large variety of specialty bearings. If you don't see it listed here call 1-905-876-1105 or eMail firstname.lastname@example.org
All information taken from the Power Transmission Handbook.
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