Vertical Wear Liner

The vertical wear liner is a hardened steel ring fitted into the center bowl of a truck bolster. It is part of the truck center bowl assembly and works alongside the horizontal wear liner that protects the floor of the bowl.

Where It Sits

The center bowl is the dished pocket at the middle of the bolster in which the car body center plate sits and on which the body pivots. The vertical wear liner lines the upright wall, or rim, of that bowl. It is typically welded into place so that the rotating edge of the center plate bears against the liner rather than against the parent casting.

What It Does

As the car runs, the body and its center plate turn slightly within the bowl on every curve and rock under load. Without protection, that motion would wear the soft cast wall of the bowl and enlarge it, loosening the fit of the center plate and allowing the truck to shift or hunt. The vertical wear liner gives a replaceable, wear-resistant surface so that wear is taken by the liner and not by the bolster itself, preserving the much more costly casting.

Wear and Inspection

A worn, cracked, or missing vertical wear liner allows excessive play between center plate and bowl and is corrected by replacing the liner rather than the bolster. Condemning limits for center bowl wear and the related liners are set by the AAR interchange rules and field manual.