What are the types of track grinding machines?
What are the types of track grinding machines?
Track grinding machines are classified three ways. By duty: multi-head grinding trains for main-line preventive work, compact machines for switches and turnouts, and portable units for isolated defects. By spindle orientation: vertical-axis, which copies the rail head from above, or horizontal-axis, which surfaces the rail head from the side. By control: manual handwheel feed, powered copying, or CNC intelligent copying against a stored target profile. In practice the location of the defect picks the family, and the required surface finish picks the control type.
The three families, and where each one belongs
| Family | Typical machines | Work it is built for | Real output reference |
|---|---|---|---|
| Multi-head grinding train | GMC16A, PGM-48 / PGM-96C (GMC-96X class) | Main-line preventive and corrective grinding of corrugation, fatigue cracks and rail-head geometry | A group of 48 stones cuts 10-15 km continuously; 18.72 pass-km were completed inside a single 2-hour night possession at Liuzhou in 2022 |
| Switch and turnout machine | RGH20C class turnout car; RCG-C65 CNC copying; RCG-L50 lithium | Frogs, switch blades, wing rails and crossings, where clearance and copying quality matter more than speed | Turnout geometry judged on profile deviation and surface finish, not on metal removed |
| Portable and handheld unit | MRC-S 150 / 125 class machines (ZA / F20 wheels, 6000-7500 rpm spindles) | Welds, spot defects, short station tracks and anywhere a train cannot reach | One or two operators, repositioned by hand between defects |
The choice between the first two rows is usually obvious; the expensive mistake is using the third family where the first is needed, or the reverse. A complete grinding programme normally runs a train for the line and compact machines for the switches, which is why both appear in the RailwayCare grinder range. If you are comparing the two ends of that range, start with portable grinder versus full-size grinding train.
Spindle orientation and copying control: the second axis of classification
| Class | How it cuts | What it is good at | Example |
|---|---|---|---|
| Vertical-axis machine | Spindle perpendicular to the rail head, cutting from above with the wheel face | Strong copying: rail-head contour recovery, frog and switch-blade curves, guard rails | RCG-V50 multifunctional vertical-axis grinder |
| Horizontal-axis machine | Spindle parallel to the rail head, cutting from the side | Flat planar work: rail-head surfacing, levelling and large accessible areas | Conventional portable horizontal grinders |
| Manual feed | Operator feeds the wheel by handwheel and judges the surface visually | Spot repairs and rough stock removal | Handheld machines |
| CNC intelligent copying | Machine stores the target profile and follows it automatically | Crossings and blades where the geometry must not drift between passes | RCG-C65 CNC copying rail grinder |
Orientation is not a marketing detail. A vertical-axis head can hold a curved contour because the cutting contact moves around the profile; a horizontal-axis head naturally produces a flat. That is why turnout work is dominated by vertical-axis and CNC machines, and why the copying control system matters as much as the motor.
What the different types deliver in numbers
All three families are judged against the same acceptance criteria, whatever their size: profile deviation ≤ 0.3 mm against a 1 m straightedge, surface finish Ra ≤ 10 μm, no continuous blueing, grinding depth generally ≤ 0.5 mm per pass and a ramp slope steeper than 1‰. On switch work a further measure is available: after turnout grinding, car-body lateral acceleration has been recorded falling from about 0.20 m/s² to 0.04-0.08 m/s² across the crossing.
Productivity separates the families more than quality does. Taking the widely used 12-head grinding unit design as a reference point: 12 motors of 12 kW each, spindle speeds of 4000-6500 rpm, head tilt from -72° to +20°, a working rate around 300 m/h, 0.2-0.3 mm removed per pass, dust extraction of 5000 m³/h, and one set of 12 stones covering roughly 1000 m. A full grinding train multiplies those figures by its number of cars; a handheld machine cannot approach them at all, which is why the smallest type is reserved for defects rather than for kilometres.
Whichever class you run, the cutting edge is the same consumable, and Molaton is the product brand behind it — the same 50 m/s, zirconia-alumina, resin-bonded, glass-fibre wrapped wheels used across the range in railway grinding wheels and in rail grinding machines. Rail grades handled in these applications are 60 and 75 kg/m, typically U71Mn, U75V and the wear-resistant U78CrV.
Related questions you may also ask
How do I choose a railroad track grinding machine? What is a rail grinding machine and how does it work? How do I choose a railroad rail grinder for switch and turnout work? Rail grinding solutions by line typeNot sure which type you need?
Send us your track types, the defects you are seeing and the size of your possession windows. RailwayCare will tell you which family of machine fits — train, turnout machine or portable unit — and match the wheel specification to it.
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