Hegenscheidt-MFD RP 750

The UHB 500 is an underfloor machine — the rail vehicle drives onto the machine and wheel sets are reprofiled without extraction from the vehicle. The RP 750 is a between-centers wheel reprofiling lathe for extracted wheel sets — the axle is removed from the vehicle and mounted in the machine for reprofiling. The UHB 500 is faster for routine maintenance (30-90 minute vehicle turnaround), while the RP 750 handles larger wheel diameters (up to 750mm vs 500mm reprofiling range), provides higher precision between-centers reprofiling, and is suited to heavy overhaul workflows where wheel set extraction is already part of the scope.

When a wheel set is turned between centers — with driving and supporting centers engaging the center holes in each end of the axle — the tread profile is generated with the wheel rotating about the true axle centerline. This ensures that the reprofiled tread is concentric with the axle journal bearing seats to within the machine's accuracy (roundness <0.05mm). If the tread is not concentric with the journals, the wheel set runs eccentrically in service, producing vibration and noise even with a geometrically correct tread profile. Between-centers reprofiling is the precision standard for quality wheel set maintenance.

The RP 750's CNC control measures the tread diameter of both wheels before machining, calculates the maximum diameter that can be achieved on the worn wheel (limited by the smaller-diameter wheel's condition), and sets the target tread diameter for both wheels to match within specification (typically <0.1mm difference). Both wheels are turned simultaneously to the matching target diameter. This matched-diameter result is critical — a wheel set with mismatched tread diameters will tend to steer the vehicle in the direction of the larger wheel, increasing wheel flange and rail wear.

The carbide profiling inserts must be replaced periodically — insert life depends on wheel material (cast iron vs steel), wear condition (lightly worn vs heavily worn with hard spots), and cutting parameters. Typical insert life is 40-120 wheel sets per insert, depending on conditions. The profile accuracy of the machine should be verified periodically using a calibrated profile gauge — Hegenscheidt recommends formal machine calibration annually, with regular in-process verification as part of quality system requirements for wheel set maintenance.

Yes. The RP 750 requires a level, reinforced concrete floor rated for the machine weight plus the maximum wheel set handling loads, with sufficient bay height for overhead crane access (minimum 5m under hook for 4,000 kg axle handling). Three-phase electrical service (460V or 380V depending on region) at 150-250 kW connected load is required. Chip conveyor and coolant system utilities must be designed into the installation. Hegenscheidt-MFD provides installation engineering documentation as part of the machine supply and recommends early engagement with the civil contractor for new wheel shop facilities.