Crane rails support the wheels of overhead travelling cranes, gantry cranes, port cranes and other heavy lifting equipment. In the Chinese standard series, the profiles are designated QU70, QU80, QU100 and QU120, where the number is the nominal head width in millimetres. These rails are rolled with a raised running surface and a wide flat base so that the wheel load is distributed over a large bearing area, and the I-shaped cross-section provides the bending strength needed on runway beams.
QU Series Technical Parameters
| Size | Head width (mm) | Height (mm) | Base width (mm) | Web thickness (mm) | Weight (kg/m) | Material | Standard length |
| QU70 | 70 | 120 | 120 | 28 | 52.8 | U71Mn / U75V | 12 m |
| QU80 | 80 | 130 | 130 | 32 | 63.69 | U71Mn / U75V | 12 m |
| QU100 | 100 | 150 | 150 | 38 | 88.96 | U71Mn / U75V | 12 m |
| QU120 | 120 | 170 | 170 | 44 | 118.1 | U71Mn / U75V | 12 m |
U71Mn and U75V are pearlitic rail steels with good wear resistance and weldability. Where the crane duty is heavy or wheel pressures are high, heat-treated or alloyed variants with higher hardness can be specified, but the profile geometry remains the same so that existing fastenings and welds stay compatible.
What Makes Crane Rails Different from Railway Rails
A standard railway rail is designed for wheel-rail contact on the head with lateral guidance from the flange, while a crane rail carries flat-faced crane wheels whose load path is closer to the centre of the head. As a result, crane rail heads are wider relative to height, the web is thicker to resist the high local pressure under a crane wheel, and the base is proportionally wider for load spread. QU rails must therefore never be substituted with ordinary railway rails, and railway clips and pads are not directly interchangeable with crane rail fastenings.
Typical Applications
Steel mills: ladle cranes, charging cranes and finishing mill cranes operating at high temperature with heavy loads.
Ports and shipyards: gantry cranes and ship lift systems on exposed, salt-laden runways.
Power plants and heavy industry: turbine hall cranes and maintenance gantries with moderate duty but long spans.
Precast yards and rail transit depots: gantry cranes handling sleepers, beams and concrete segments.
Selection Points for Buyers
Select the QU profile from the maximum wheel load per wheel, wheel spacing and runway beam design, then confirm the material grade against the duty cycle. Specify whether rails are needed drilled for joint bars, with welded joints, or supplied plain for on-site welding. For curved runways, order pre-curved rails or allow for on-site bending; the minimum bending radius depends on the profile. Check the rail pad and clip system separately: crane rail fastenings are available as clamp-and-bolt assemblies rated for the higher wheel pressures, and rail pads must be matched to the QU base width and the runway structure. Verify straightness and surface quality at loading because crane rail top surface tolerance directly affects wheel wear and smooth running.
Common Misconceptions
QU100 does not weigh 100 kg/m: the number is the head width, and the actual weight is 88.96 kg/m. A heavier QU rail is not automatically safer on a light runway beam, because the beam, fastenings and crane wheel geometry must match the profile. And QU rails cannot be installed with ordinary railway rail clips; the fastening system must be designed for crane wheel loads and the wider base.
FAQ
What does the number in QU70 mean?
It is the nominal head width in millimetres: QU70 has a 70 mm wide head. It is not the rail weight.
Which QU size should I choose for a 50 t overhead crane?
The selection depends on wheel load and spacing rather than crane capacity alone. A 50 t crane with four wheels often runs on QU70, while heavier wheel loads push the design to QU80 or QU100. The runway designer should calculate the required rail head width from the wheel pressure.
What steel grade is used for QU rails?
U71Mn and U75V are the common grades, with good wear resistance and weldability. Heat-treated variants can be ordered for severe duty, high temperature or abrasive environments.
What length are QU rails supplied in?
Standard supply is 12 m. Longer or shorter pieces, drilled fishplate holes and special surface treatment can be arranged at the mill.
Can QU rails be welded?
Yes, thermite or flash welding is used on crane runways to remove joints, and U71Mn/U75V grades are weldable. Welding procedure approval and post-weld inspection are recommended for safety-critical runways.
How is a crane rail fastened to the runway beam?
Typical systems use clips or clamps bolted to the beam, with rubber pads between rail and beam to cushion wheel impact. The fastening must allow for thermal expansion while holding the rail against lateral and longitudinal forces.