A needle roller bearing is a special type of
roller bearing
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races. The relative m ...
which uses long, thin
cylindrical rollers resembling needles. Ordinary roller bearings' rollers are only slightly longer than their diameter, but needle bearings typically have rollers that are at least four times longer than their diameter.
Like all
bearings, they are used to reduce the
friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of ...
of a rotating surface.
Compared to
ball bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...
s and ordinary roller bearings, needle bearings have a greater surface area in contact with the
race
Race, RACE or "The Race" may refer to:
* Race (biology), an informal taxonomic classification within a species, generally within a sub-species
* Race (human categorization), classification of humans into groups based on physical traits, and/or s ...
s, so they can support a greater load. They are also thinner, so they require less
clearance between the
axle and the surrounding structure.
Needle bearings are heavily used in automobile components such as
rocker arm
In the context of an internal combustion engine, a rocker arm is a valvetrain component that typically transfers the motion of a pushrod to the corresponding intake/exhaust valve.
Rocker arms in automobiles are typically made from stamped steel ...
pivots,
pumps,
compressors
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
Compressors are similar to pumps: both increase the pressure on a fluid and both can trans ...
, and
transmissions. The
drive shaft of a rear-wheel drive vehicle typically has at least eight needle bearings (four in each
U joint
A universal joint (also called a universal coupling or U-joint) is a joint or coupling connecting rigid shafts whose axes are inclined to each other. It is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges l ...
) and often more if it is particularly long, or operates on steep
slopes
In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is used ...
.
See also
*
Race (bearing)
The rolling-elements of a rolling-element bearing ride on races. The large race that goes into a bore is called the ''outer race'', and the small race that the shaft rides in is called the ''inner race''.
Design
In the case of ball bearings, ...
*
Tapered roller bearing
Tapered roller bearings are rolling element bearings that can support axial forces (i.e., they are good thrust bearings) as well as radial forces.
Description
The inner and outer ring raceways are segments of cones and the rollers are taper ...
References
Rolling-element bearings
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