Yoke type track rollers are single or double row units mounted on shafts or studs. They comprise thick-walled outer rings with a profiled outside surface and needle roller and cage assemblies or full complement needle roller or cylindrical roller sets.

Yoke type track rollers can support high radial loads as well as axial loads arising from slight misalignment and skewed running; they are suitable for applications such as cam gears, bed ways and conveying equipment.

The bearings are available with and without an inner ring and in both sealed and open versions.

Series PWTR is supplied as an X-life design. Due to a modified material and the optimised raceway geometry of the outer rings, the basic rating life has been increased by up to 30%.

The static and dynamic load carrying capacity has also been increased. At the same time, the stress placed on the mating track has been reduced as a result of the optimised lateral surface profile and its improved surface quality.

Due to these measures, highly robust bearing arrangements with an extended operating life can be achieved.

Yoke type track rollers with a crowned outside surface are predominantly used in practice since they are often inclined in relation to the mating track and edge stresses must be avoided.

The radius of curvature of the outside surface is R = 500 mm. In the case of NNTR..-2ZL, the radius is indicated in the dimension table.

The series NATR..-PP, NATV..-PP, NUTR and PWTR..-2RS have an outside surface with the optimised INA profile.

In yoke type track rollers with this curvature profile (Figure to Figure ):

• the Hertzian pressure is lower
• edge loading under tilting is lower
• wear of the mating track is reduced
• the operating life of the mating track is extended.

Yoke type track rollers RSTO and RNA22..-2RSR do not have an inner ring. They are particularly compact but require a hardened and ground raceway on the shaft or stud.

Series RSTO is not self-retaining. This means that the outer ring and the needle roller and cage assembly can be fitted independently of each other.

In RSTO and RNA22..-2RSR, the rolling elements are guided by a cage. These designs do not have axial guidance of the outer ring. Axial guidance of the outer ring and needle roller and cage assembly must be provided in the adjacent component; see section link.

RSTO is not sealed, series RNA22..-2RSR has lip seals on both sides.

The bearings are greased with a lithium complex soap grease to GA08.

These yoke type track rollers are used if the shaft or stud does not have a hardened and ground raceway.

STO is not self-retaining. This means that the outer ring, needle roller and cage assembly and inner ring can be fitted independently of each other.

The series STO, NA22..-2RSR, NATR and NATR..-PP have a cage. The series NATV and NATV..-PP have a full complement needle roller set, while yoke type track rollers NUTR, PWTR..-2RS and NNTR..-2ZL have a full complement cylindrical roller set.

Bearings without a cage have the largest possible number of rolling elements and therefore have particularly high load carrying capacity. Due to the kinematic conditions, however, the speeds achievable with these bearings are somewhat lower than those achievable with the cage-guided yoke type track rollers.

STO and NA22..-2RSR do not have axial guidance of the outer ring. This must be provided in the adjacent construction; see section link.

In NATR and NATV, axial guidance is provided by contact washers and axial plain washers. In NUTR, the outer ring is guided by the rolling elements, in PWTR..-2RS and NNTR..-2ZL it is guided by the central rib and the rolling elements.

Yoke type track rollers PWTR..-2RS-RR are protected against corrosion by the special coating Corrotect^®. For a description of the coating, see link.

The seals used in yoke type track rollers are shown in the following table.

In the three-stage concept, there is a gap seal between the plastic axial plain washer and the outer ring and a labyrinth seal between the formed seal lip and the undercut in the outer ring.

The disc spring shape of the axial plain washers gives a preloaded contact seal as the third stage. It also provides axial sliding contact between the outer ring and contact washers, thus reducing wear and grease consumption.

The bearings are greased using a lithium complex soap grease to GA08 and can be lubricated via the inner ring. Relubrication can be carried out using Arcanol LOAD150.

Yoke type track rollers can be used at temperatures from –30 °C to +140 °C. In sealed bearings (suffix 2RS and 2RSR) and bearings with a plastic cage (suffix TV), the temperature range is restricted to between –30 °C and +120 °C.

Note the information on the operating temperature range in Technical Principles, Lubrication.

Yoke type track rollers NATR..-PP and NATV..-PP are suitable for operating temperatures from –30 °C to +100 °C, restricted by the grease and the seal material.

Suffixes for available designs: see table.