needle bearings

Needle bearings have a large surface area that is in contact with the bearing outer surfaces compared to . Additionally there is less added (difference between the of the and the diameter of the bearing) so they are much more compact. The typical structure consists of an inner race (or sometimes merely a shaft), a needle cage which orients and contains the needle rollers, the needle rollers themselves, and an outer race.

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.

Needle bearings are heavily used in engine components such as rocker arm , , , and . The of a rear-wheel drive vehicle typically has at least 8 needle bearings (4 in each ) and often more if it is particularly long, or operates on steep .

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.