Train Wheelset Geometry Scanning

Measuring Wheelset and Wheel Dimensions

The interaction between wheel and rail stresses the wheels of rail vehicles tremendously. The wheel profile geometry, the radial and axial runout tolerances and the wheel disks’ position on the shaft are quality parameters crucial to a rail vehicle’s safe operation and high ride comfort.

As vehicle speeds continue increasing, the assurance of the quality parameters by objective measurements is extremely important during both the manufacture and necessary maintenance of wheelsets.

Based on its OptoInspect technology 3D, the Fraunhofer IFF developed a non-contact measurement system that fully scans every relevant geometric parameter of wheelsets and wheels.

Technical Solution for a Wheelset Measuring Stand

A fully automatic measuring stand consists of components for wheelset handling and the actual measuring unit. The wheelset handling system inserts wheelsets in and removes them from the measuring position and moves them to scan data. Optical line and point sensor clusters that operate based on the principle of triangulation are employed to scan data. Five sensor clusters operate in one common coordinate system and each digitizes relevant areas of the surfaces of wheel profiles, wheels and shafts. The sensor can be adjusted radially to accommodate different wheel diameters.

Data is evaluated in software modules modified for specific tasks. Wheelset and wheel profile coordinate systems are ascertained in a first step and the geometry parameters are computed in a second step. A computerized system controls the motion systems, acquires data through sensor clusters, and evaluates and logs data.

Results of Measurement (in Compliance with Deutsche Bahn AG Guidelines)

Wheelset dimensions

• Distance of inner wheel flange faces (AR)
• Distance of inner wheel flange face to the center of the wheelset shaft (AR1, AR2 and/or c, c’)
• Measuring circle diameter (dM)
• Radial runout tolerance in the measuring circle planes (H)
• Axial runout tolerance of the wheel disks (G)
• Diameter and radial runout tolerance of the wheelset shaft (F)
• Gauge size (SR)

Wheel profile dimensions

• Flange thickness  (Sd)
• Flange height (Sh)
• Cross dimension of the flange flank (qR)
• Flange and/or rim width (BR)

The system is flexibly upgradable to measure other parameters (e.g. for disk brakes or drive components).

An accredited calibration lab has certified this wheelset measuring stand’s performance.