INA NATR17 Stützrollen (17x40x21)

As a track or cam roller, this component runs directly on a mating track or cam surface. At 17x40x21 mm and a unit weight of 0.148 kg, the installation envelope is fixed; further technical details are held in the specification table. On a support roller, low frictional torque counts twice: it often runs slowly, frequently oscillating, and is not driven but carried along by the track.

This version of the support roller is closed on both sides with shields that work without contact: they narrow the gap far enough that the lubricant stays in the rolling chamber and coarse ingress from the running track does not get in, without creating a friction surface. For this design that is an important point, since a support roller is not driven but carried along by the contact with its track.

A high breakaway or frictional torque causes the roller to slide on the track instead of rolling on it, and thereby generates wear at exactly the place it is meant to protect — at the running surface and at the mating track. A shield acting without contact keeps that torque low. The limit is just as clearly stated: against moisture, splash water and fine abrasive dust, shields form no tight closure; where such influences are permanently present, a bearing seal is the right choice.

Nothing changes in the rest of the construction. The thick-walled, hardened outer ring is the running surface and takes the contact pressure from the contact with a rail, a track or a cam disc; the mating track, with its hardness and flatness, belongs to the layout; the profile of the running surface — cylindrical or crowned — determines how the roller copes with an angular error relative to the track.

The roller is set onto a journal through its bore and supported on both sides. Rings and rolling elements are made of standard bearing steel.