Small cylindrical rollers with the length are several times more than their diameter is called needle rollers.
Radial needle roller bearings are designed to accommodate only radial loads. With the equal load capacity, they have much smaller radial dimensions compared to the dimensions of other types of bearings having with them the identical hole diameters. This property makes them very popular to use in the machines with limited radial space. A negative characteristic of the bearings is their extremely small capacity to accommodate the angular shaft misalignments relative to the housing.
The radial needle roller bearings have enormous kinds of designs. The most common are bearings with the pressed outer rings, with the rings made of bearing steel, as well as the cages with the rollers without rings. Usually, the bearings have one or two rows of rolling elements. The bearings can be open or have protective contact seals.
Radial needle roller bearings are produced with pressed steel or glass fiber reinforced polyamide cages. To provide a very high radial load capacity the bearings can be manufactured without the cage with the maximum number of rollers.