Bolster Bowl Shim

A bolster bowl shim is a round piece of mild steel placed in the bolster bowl to raise the center plate. Shims were once permitted for used on cars with 263,000 lb gross rail load or less, but due to their misuse on heavier cars shims are now prohibited on all cars. Instead, horizontal wear liners made of various thicknesses of hardened steel must be used instead of shims.