Needle roller bearing
Encyclopedia
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
which uses small cylindrical rollers
Cylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...
. They are used to reduce friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
of a rotating surface.
Needle bearings have a large surface area that is in contact with the bearing outer surfaces compared to ball bearing
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 by using at least two races to contain the balls and transmit...
s. Additionally there is less added clearance (difference between the diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
of the shaft
Axle
An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...
and the diameter of the bearing) so they are much more compact. The typical structure consists of an a needle cage which orients and contains the needle rollers, the needle rollers themselves, and an outer race(sometimes housing itself).
Radial needle bearings are cylindrical and use rollers parallel to the axis of the shaft. Thrust needle bearings are flat and use a radial pattern of needles.
Full compliment bearings have solid inner and outer rings and rib-guided cylindrical rollers. Since these bearings have the largest possible number of rolling elements, they have extremely high radial load carrying capacity and are suitable for particularly compact designs.
Needle bearings are heavily used in engine components such as rocker arm pivot
Pivot
Pivot may refer to:* Pivot, the point of rotation in a lever system* More generally, the center point of any rotational system* Pivot joint, a kind of joint between bones in the body* Pivot turn, a dance move- Computing :...
s, pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
s, compressors
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
, and transmissions
Transmission (mechanics)
A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...
. The drive shaft
Driveshaft
A drive shaft, driveshaft, driving shaft, propeller shaft, or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement...
of a rear-wheel drive vehicle typically has at least 8 needle bearings (4 in each U joint) and often more if it is particularly long, or operates on steep slopes.
Additional clarification of Needle Roller: According to "Marks' Standard Handbook for Mechanical Engineers", a Needle Bearing is a roller bearing with rollers whose length are at least four times their diameter.
See also
- Race (bearing)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.-Manufacture:...
- Schaeffler GroupSchaeffler GroupThe Schaeffler Technologies GmbH & Co. KG is a privately owned major manufacturer of rolling element bearings for automotive, aerospace and industrial uses. In August 2008 the firm agreed to a staggered €12 billion acquisition of larger rival Continental AG, whereby Schaeffler will defer taking a...
- SKF GroupSKFSKF, Svenska Kullagerfabriken AB , later AB SKF, is a Swedish bearing company founded in 1907, supplying bearings, seals, lubrication and lubrication systems, maintenance products, mechatronics products, power transmission products and related services globally.-History:The company was founded on...
- Timken CompanyTimken CompanyThe Timken Company is a global manufacturer of bearings, alloy steels, and related components and assemblies.- History :The company was founded by Henry Timken in St. Louis, Missouri in 1899 and incorporated as The Timken Roller Bearing Axle Company. A year earlier, in 1898, Timken got a patent...
and former Torrington CompanyTorrington CompanyThe Torrington Company was a firm that developed in Torrington, Connecticut, emerging as a rename from the Excelsior Needle Company. It used a "cold swaging" technique to create sewing machine needles and other needles from cold metal, and was the largest employer in Torrington.James Alldis was...