Schaeffler North America

Yoke and stud type track rollers, needle roller type

Reduced Hertzian Pressure

Optimized INA Profile

The new outer ring outside surface – the optimized INA profile – leads to reduced Hertzian pressure between the outer ring and mating track compared to conventional profiles.


The reduction in the Hertzian pressure reduces the load on the mating track, as shown here for the material GGG-50. Tests schow that this reduction has a pominent influence on the wear of the mating track.

  • Low load (1)
  • High load (2)

  • Optimized INA profile (A)
  • Outer ring with
    R=500 mm (B)

y: Wear [g] after 360 000 overrolling cycles  

x: Radial load [kN]
y: Mean running time [%]
Running Time

Depending on the load, the new profile has a positive influence on the fatigue life of the mating track, as shown here for the material 42 CrMo4V. This leads to significantly longer mating track life or, alternatively the option of using more economical mateials.

  • with plastic axial plain
    washer (A)
  • without axial plain washer (B)



The optimized INA profile reduces the Hertzian pressure in the contact zone. This gives decisive user benefits

  • reduced wear
  • increased rigidity
  • longer operating life