Needle roller and cage assemblies (see a below), represent the most simple design of needle roller bearings. They consist of needle rollers that are loose retained by the cage only. Needle roller and cage assemblies are designed to run directly on the running surfaces of both the shaft and the housing. Thus they provide simple, economic and significant space - saving bearing arrangements that require less sectional height. These surface areas of shaft and housing are designed to act as raceways, therefore they require to be produced to the same standards as for bearing ring (e.g. hardened and ground, etc.). For special purposes, such as crank shaft applications, specially developed designs are available. Drawn cup needle roller bearings (below b and c) are both produced with open (a) and closed (b) ends. They consist of a needle roller and cage assembly which runs in a hardened, deep drawn sheet steel outer ring. The thin - walled outer ring, which is ungrounded, generates its final shape by press forming into its housing bore. For the full utilisation of their potential load carrying capacity the outer rings require satisfactory support.

Such satisfactory support is achieved by a suitable interference fit in the housing bore. Usually there is no additional axial location requirements. The drawn cup needle roller bearings with both open sides, (see Above b), are typical non - locating bearings, drawn cup needle roller bearings with a closed end (Above. c) are capable of supporting minor axial forces due to their profiled closed ends. Drawn cup needle roller bearings with closed end (Above. c) are optimum to seal up bearing arrangements. Drawn cup needle roller bearings with both, open or closed ends usually run directly onto shafts. These, however, must be designed accordingly. Where such is not possible, they may be used together with needle roller bearing inner rings. Both types of drawn cup needle roller bearings (i.e. either open or with one end closed) are also available with contacting seals integrated in the outer ring. Whilst the type with one side only open has a seal integrated in the open side (suffix RS, see Above f), the drawn cup needle roller bearings with both sides open are available either with just one side sealed (suffix RS, see Above d) or with two seals (suffix .2RS, see Abpve e) fitted. The material used for the contacting seals is a wear - resistant synthetic nitrile rubber (NBR) this prevents bearing contamination by foreign particles and impurities. The seal material is suitable for operation temperatures of -30 deg C up to +120 deg C. Sealed drawn cup needle roller bearings are like needle roller bearings in general, needle roller and cage assemblies, and drawn cup needle roller bearings are less suitable to compensate for misalignments. Despite the modified contact geometry of the needle rollers, used in NKE needle roller bearings, it is recommended any misalignment is avoided since even small misalignments may generate high running noise.NKE needle roller and cage assemblies and drawn cup needle roller bearings are fitted with pressed steel cages as standard. The exceptions are small needle roller and cage assemblies and drawn cup needle roller bearings that feature solid polyamide cages (suffix TN) as standard. NKE Needle roller and cage assemblies are fitted with needle rollers according to DIN 5402, Part 3, grade G2. The diameter variation of these Needle rollers is sub-divided into 9 groups, each group of rollers having a maximum variation of 2 u.m, (i.e. 0 to -2 um, -1 to -3 um, -2 to -4 um etc). The width tolerance of NKE needle roller and cage assemblies is, irrespective of the bearing size, constant for all widths at; -0.2 mm / -0.8 mm The control of boundary dimensions of needle roller and cage assemblies is only possible using functional calibrated measuring devices such as master ring gauges, bore plugs or mandrels etc.

All information courtesy NKE Bearings Austria www.nke.at