Track Rollers are forged from a boron steel alloy and then through hardened to a good core hardness. This prevents the bushings from loosening. The roller outside diameter is also deep heat treated through wear limit for maximum wear life.
Tractor-style rollers have an upset center shaft to absorb heavy thrust loading and offer at least 30% more wear life than excavator-style rollers. Best for machines that spend a lot of time traveling at high speeds.
Excavator-style rollers are better in high-impact conditions because of its heav-duty, large diameter shaft.