Needle bearings
Characteristics of Needle Bearings
Needle roller bearings are characterized by thin cylindrical rolling elements. Although they have a small cross-section, they have a high load carrying capacity and are used primarily in applications where only limited installation space is available. In general, needle roller bearings, like ball bearings, are differentiated into radial and axial designs. Radial needle roller bearings with or without an inner ring can only support radial forces and are suitable for medium loads at medium speeds. They are mainly used in gearboxes and in general mechanical engineering.
If an inner ring is dispensed with, the size of needle roller bearings can be further reduced. However, in this case the shaft serves as a raceway, which must be hardened and ground to obtain full load carrying capacity. Needle roller bearings are available as solid needle roller bearings with and without an inner ring, with and without ribs, as a needle roller and cage assembly, drawn cup needle roller and cage assembly, drawn cup needle roller bearing or adjustable needle roller bearing. All designs are available in single row and multi-row versions. Furthermore, there are radial and thrust bearings as well as angular contact roller bearings. They can all only support forces acting in one axis. If axial and radial forces have to be accommodated, two bearings are required. There are also combined needle roller/axial deep groove ball bearings that can support axial and radial forces.
The different designs of the Needle Roller Bearings
Solid Needle Roller Bearings
Solid needle roller bearings with an inner ring comprise a needle roller and cage assembly, a machined solid outer ring (similar to cylindrical roller bearings) and an inner ring which can be removed. 
Therefore, a needle roller bearing without an inner ring can be supplemented with a suitable inner ring as an accessory. With wider inner rings, axial displacements other than those of the standard design can also be realized.
Solid needle roller bearings without an inner ring comprise a needle roller and cage assembly and a machined outer ring. The shaft serves as a mating partner or a suitable inner ring is used as an accessory. With wider inner rings, axial displacements other than those provided for in the standard can also be realized.
Needle roller and cage assembly
Needle roller and cage assemblies are single or double row units consisting of a cage and the needle rollers. Since their radial overall height corresponds only to the diameter of the needle rollers, needle roller and cage assemblies permit bearing arrangements with the smallest possible radial installation space.
They have very high load carrying capacity, are predestined for high speeds and are particularly easy to fit. The needle rollers run directly on the shaft and housing. For this reason, they can only be used if the shaft and housing bore can be designed as raceways, i.e. hardened and ground.
The radial internal clearance can be influenced by the needle roller and cage assembly and the shaft and housing tolerance. Needle roller and cage assemblies require that the raceway on the shaft and in the housing is hardened and ground.
Drawn Cup Needle Roller Bearings
Drawn cup needle roller bearings are needle roller bearings with a thin, non-cutting outer ring. They are mainly used when the housing bores cannot be designed as raceways for needle roller and cage assemblies. They are also available in a full needle design.
Due to the maximum number of needle rollers, full-needle drawn cup needle roller bearings allow the highest load capacity in the smallest installation space. However, they do not achieve the speeds possible with drawn cup needle roller bearings with cage. Since the needles are not held mechanically in drawn cup needle roller bearings, the needle rollers are secured with a special grease for transport and assembly. However, this has only an insufficient permanent lubricating effect. For this reason, relubrication is recommended after installation.
Drawn Cup Roller Clutch
Drawn cup roller clutches are similar in design to drawn cup needle roller clutches, but offer the extended function of a one-way clutch and transmit torque in one direction. Drawn cup roller clutches of the HF series only transmit torques. Drawn cup roller clutches of series HFL also absorb radial forces due to the integrated plain or rolling bearings.
Drawn Cup Needle Roller Bearings closed end
Drawn cup needle roller bearings are closed on one side. This makes them ideal for closing off bearing positions on shaft ends. This provides accident protection when the shaft is rotating and protects the bearings from dirt and moisture. Depending on the size, the base is smooth or beaded or stiffened. Due to the profiled base, small axial guides are also possible.
Alignment Needle Roller Bearings
Alignment needle roller bearings are units consisting of non-cutting outer sleeves, plastic support rings with a hollow spherical inner shape, outer rings with a spherical outer surface, needle roller and cage assemblies and removable inner rings. This type of needle bearing compensates for static misalignment of the shaft and thus tolerates misalignment of the shaft relative to the housing. Adjustable needle bearings have a tight fit in the housing bore. This means that the bore can be manufactured easily and economically.
Yoke Type Track Roller
The back-up roller is a highly rigid bearing system. The yoke type track roller contains a needle roller bearing and is used as a guide roller for cams and linear motion. They have a solid outer ring.
This is necessary because the outer ring rotates and continuously contacts the contact surface. The outer ring is also capable of withstanding impact loads. The needle rollers located inside the back-up roller and the precision cage prevent the rollers from skewing and ensure optimum rotational movements. Rotational movements at high speeds are therefore no problem. Back-up rollers can basically be divided into two types: One type with separable inner ring and one type without separable inner ring. The outer ring can be cylindrical or spherical. The yoke type track roller is used in numerous applications: e.g. cam gears of automatic machines, carrier systems, conveyors, book binding machines, tool changers for machining centers, pallet changers, automatic coating machines and storage and retrieval machines.
Axial Needle Bearings
Axial needle roller bearings are units consisting of axial needle roller and cage assemblies and axial bearing washers with centring collar. 
They can be combined with drawn cup needle roller bearings, drawn cup needle roller bearings and needle roller bearings. The contact surface for the needle roller and cage assembly must be hardened and ground.
Combined Needle Roller Bearings
Combined needle roller bearings consist of a radial needle roller bearing and a thrust bearing part. The special feature is the parallel support of radial and axial loads. Their use is particularly advantageous where the axial loads can no longer be accommodated by simple thrust washers due to their size, due to high speeds or insufficient lubrication and other locating bearings would require too much installation space. The respective lubrication intervals for the radial and the axial bearing part are to be determined separately. The shorter of the two determined lubrication intervals is to be applied.
Inner Rings
Inner rings are made of hardened rolling bearing steel and have finely machined or ground raceways. They are used when:
- In the case of needle roller and cage assemblies, drawn cup needle roller bearings, drawn cup needle roller bearings, the shaft cannot be used as a raceway.
- Needle roller bearings must be combined with wider inner rings to allow greater axial displacement of the shaft in relation to the housing.
- Optimal running surfaces are necessary for the sealing lips
PACH Systems offers you a wide product range of different needle bearings. For this purpose, we work together with our long-standing partners. Please let us know your requirements via our contact form. We will be happy to provide you with a non-binding offer or contact you to discuss the details.
