NTN NUTR204/3AS Stützrollen (20x47x25)

As a track or cam roller, this component runs directly on a mating track or cam surface. At 20x47x25 mm and a unit weight of 0.254 kg, the installation envelope is fixed; further technical details are held in the specification table. The hardened, thick-walled outer ring still runs directly on a rail, a track or a cam disc. This support roller is executed with a non-contact seal on both sides.

The operating principle differs fundamentally from that of a bearing lip: instead of wiping the ingress away at a contact point, the arrangement leads it along a narrow, repeatedly deflected path on which particles and liquid lose their kinetic energy and the lubricant is retained in the rolling chamber. Two properties follow from this. First, no additional frictional torque arises, which on a roller that is not driven but carried along by its track acts directly on the rolling behaviour and leaves the permissible speed unlimited by a sealing element.

Second, nothing that bears against a surface wears: the protective effect is retained over the operating life, whereas a lip recedes along with the ingress — at a running track with constant debris, that is a difference which shows up in maintenance. The limit lies where a tight closure is required: against standing water, high-pressure cleaning and fine, permanently present dust, a non-contact seal offers no complete protection.

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 fixes how much angular error relative to the track is permissible; 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.