Rail road car and truck therefor

A rail road car truck having:

• a first sideframe, a second sideframe spaced from the first sideframe, and a bolster extending in a cross-wise direction between the first and second sideframes, the bolster being spring mounted to the first and second sideframes;
• the first and second sideframes each having sideframe pedestal seats mounted on wheelsets to permit the truck to roll in a longitudinal direction along rail road tracks;
• the first and second sideframes each having a bottom spring seat upon which a main spring group is seated;
• the bolster having first and second ends, each of the first and second ends having an upper spring seat that sits atop springs of one of the respective spring groups;
• the sideframes being mounted to swing in the cross-wise direction;
• said bolster being movable cross-wise relative to the wheelsets through a lateral travel displacement, δ;
• said lateral travel displacement, δ, including a first lateral travel component of displacement and having an associated component of lateral stiffness, kpendulum, measured from a respective sideframe pedestal seat to the bottom spring seat, and a second lateral travel component of displacement and another associated component of lateral of stiffness, kspring shear measured between the bottom spring seat and the top spring seat;
• the first and second lateral travel components being additive, δ being larger in magnitude than each of the first and second lateral travel components individually;
• the kpendulum being softer than the kspring shear;
• a first group of friction dampers mounted to work between a first end of said bolster and said first sideframe, a second group of friction dampers being mounted to work between a second end of said sideframe and the second end of the bolster;
• each of said groups of friction dampers including a first damper and a second damper, the first damper being mounted over a first spring of one of the spring groups, the second damper being mounted over another spring of one of the spring groups, the first spring being offset sideways from the second spring in the said cross-wise direction.