NTN NA2205 LL/3AS Stützrollen (25x52x18)

As a track or cam roller, this component runs directly on a mating track or cam surface. At 25x52x18 mm and a unit weight of 0.216 kg, the installation envelope is fixed; further technical details are held in the specification table. The gap seal is the simplest form of shielding: a closely held annular gap between the components, with no sealing element of its own and no friction point.

In this version a closely held annular gap between the outer ring and the end support bounds the rolling chamber. No sealing element bears against anything, no friction point arises and nothing wears — the protective effect follows solely from the narrowness of the gap and from the lubricant filling it. The arrangement thereby holds back coarse ingress from the running track and slows the escape of lubricant, without taking up more than the space the components occupy in any case.

For a support roller this is a consistent choice where frictional torque is the priority: the roller is not driven but carried along by the contact with its track, and the less resistance it offers to starting, the more reliably it rolls instead of sliding on the track. The limits are to be named just as distinctly: against moisture, splash water, fine dust and permanently present debris, a gap offers no effective protection.

In such surroundings a non-contact or a bearing seal is the right choice, and without a lubricant supply from the construction, relubrication has to be provided for correspondingly more often. The rest of the construction follows the design: the thick-walled outer ring, hardened through the running depth, takes the contact pressure from the contact with the mating track, whose hardness and flatness have a share in determining the load capacity of the pairing; the profile of the running surface determines the permissible inclination relative to the track; the roller sits on a journal through its bore and is supported on both sides. Rings and rolling elements are made of standard bearing steel.