A design for next generation load measuring wheel sets

The design of a strain-gaged railroad wheel set with significantly improved accuracy is described. The design provides a continuous measurement of the vertical, lateral, and longitudinal forces at the wheel-rail interface, in addition to the position of the point of contact of the rail on the wheel. A finite-element analysis is used to optimize gage placement and to simulate the output of the strain gage bridges under various loading conditions. A mathematical formulation is developed which accounts for higher-order harmonics present in the bridge signals. The formulation is used to produce output signals which are virtually independent of the rotational position of the wheel set. A system of equations using these signals is solved to calculate input force and contact position values. A prototype processor provides error estimates under a variety of simulated load conditions