Recently, the Association of American Railroads (AAR) Coupler Systems & Truck Castings Committee asked MxV Rail to evaluate how warp restraint systems might be evaluated for performance and durability in service. MxV Rail performed this evaluation under the AAR’s Strategic Research Initiatives (SRI) program. Truck warp is a serious performance concern for three-piece trucks. Various types of premium trucks, all of which address the warp problem in one way or another, have entered the market over the years. Some truck designs address warp by adding additional components or hardware designed to keep the bolster square with the sideframes. Transoms (also called spring planks) and cross bracing are the most common components or hardware used to address truck warp. While transoms and cross bracing have been in service providing proven superior performance for decades,1 the problems associated with them, including fracturing of the transom plate and broken cross braces, have been…