ZEN LR208-NPPU Laufrollen (40x85x18)

As a track or cam roller, this component runs directly on a mating track or cam surface. For this ZEN bearing, 40x85x18 mm and a weight of 0.45 kg apply; the specification table holds the further technical particulars. Unlike a bearing in a housing, the load zone here travels over the whole circumference of the outer ring: it rotates through the track force.

In a track roller the load-carrying contact lies on the outside: the outer ring rolls directly on a rail, a profile or a track and is therefore executed with a thick wall and hardened through the running depth under load. This yields a difference from a rolling bearing in a housing bore that counts for the layout: because the outer ring rotates through the track force, the most heavily stressed location travels over its entire circumference instead of remaining at a fixed point on the ring.

The fatigue loading is thereby distributed differently, and scoring or indentations on the running surface pass through the contact again with every revolution. The mating track likewise belongs to the bearing arrangement: its hardness, its surface finish and its course have a share in determining what force the pairing transmits in the long term — if the roller runs on untreated structural steel, it is usually the track that wears first, and this has to be planned for in the layout.

The contact seal on both sides closes the rolling chamber and keeps out the debris that arises at every running track; it is thus the answer to the typical environment of this design, in which things are guided, conveyed and tensioned. Its frictional torque is the counterpart and has to be weighed deliberately on a roller that is not driven, as do the temperature and media limits of the seal material.

The duty profile also has to be observed: at slow running, in oscillating movement or with frequent reversal of direction, only a limited lubricant film builds up, so the choice of lubricant and relubrication gain in weight. Rings and rolling elements are made of standard bearing steel.