Patent ID: 7255048

Claim:
A swing motion rail road car truck, said truck having a maximum load rating, said truck comprising: a pair of first and second sideframes; a truck bolster mounted cross-wise between said sideframes; a pair of first and second spring groups, each spring group having a lateral shear constant, k spring shear ; wheelsets, said wheelsets having bearings mounted thereto, and bearing adapters mounted to said bearings; said truck bolster having first and second ends, each of said ends being mounted to a respective one of said sideframes on a respective one of said spring groups; said truck bolster having a range of cross-wise travel relative to said sideframes; said sideframes each having a lower region supporting one of said spring groups; said sideframes having an upper region rockingly mounted to said bearing adapters; each sideframe having a lateral deflection constant, k pendulum at said maximum load rating; k pendulum being smaller than k spring shear ; and said truck being free of unsprung cross-bracing.