What is the standard S20 rail head width for mine cars?

The standard S20 head width: 44 mm

S20 rail is defined by DIN 5901, and the standard profile is 100 mm high, 82 mm wide at the base, 44 mm wide at the head and 10 mm through the web, with a nominal mass of 19.8 kg/m. The head width of 44 mm is the design value quoted on the section drawing and is the dimension the fishplates, turnout rails and fasteners are made to.

Head width vs wheel contact band

The 44 mm figure is the full width of the head, from gauge corner to field corner. The wheel does not use all of it: a mine car wheel with a cylindrical or shallow-profiled tread normally contacts a band in the middle of the head, typically 25-30 mm wide depending on the wheel profile and the gauge. This distinction explains why some track documentation refers to smaller figures such as 30 mm when describing running surface width - that is the contact band, not the rail head dimension. When ordering rail, fishplates or turnout parts, use the nominal head width of 44 mm.

Why head width matters for mine car track

Wheel support: a head wide enough for the full wheel tread prevents edge loading that spalls the gauge corner.

Gauge retention: the head geometry works with the wheel flange to keep the car on the rail; a worn head widens the effective gauge.

Joint and turnout fit: fishplates are machined to the 44 mm head contour, so using the correct drawing matters at every joint.

Wear allowance: the 44 mm head gives a wear band that can be measured and managed before the rail reaches its condemning limit.

Steel grade and hardness for mine car service

S20 rail for mine car track is normally rolled in 55Q steel with a minimum tensile strength of 710 MPa and a hardness of 200-240 HB. This hardness is a practical match for mine car wheels on 600 mm, 762 mm and 900 mm gauge lines. For abrasive service, a higher-hardness grade can be specified, but the wheel material should be checked too, because an excessively hard rail accelerates wheel wear.

Frequently asked questions

Is the S20 head width the same for every supplier?

The nominal 44 mm head width is fixed by the DIN 5901 section drawing. Rolling tolerances apply, but all suppliers of genuine S20 rail conform to the same profile within those tolerances.

Why does my track drawing say 30 mm head?

That figure is almost certainly the wheel contact band or the machined running surface width, not the rail head. The rail section head width remains 44 mm; verify which dimension the drawing is referring to before ordering.

Can S20 rail carry mine cars designed for wider rail?

Only if the wheel profile is compatible with the 44 mm head. A wheel designed for a heavier rail with a wider head can overhang and cause gauge corner damage; check the wheel tread width against the rail head before reuse.

What is the condemning limit for S20 head wear?

Wear limits are set by the railway operator or the track standard for the line, typically defined as a reduction in head width or vertical wear in millimetres. Measure head wear at the running band, not at the corners, and follow the applicable maintenance specification.

Does the 44 mm head width suit both 600 mm and 900 mm gauge?

Yes. The head width is a rail profile property and is independent of gauge; the same S20 section is used on 600 mm, 762 mm and 900 mm gauge mine track, with sleeper spacing and fastening arranged for the axle load.

What happens if I mix S20 rail with another light rail section?

Mixing sections creates mismatched joints and turnouts. Fishplates are profile-specific, and a height difference at a joint causes impact loading. Keep one section family per line, or use transition joints if a change is unavoidable.