QU100 vs QU120 Crane Rail: Dimensions, Weight and Application Differences
Sep 29, 2025
QU100 and QU120 at a glance
QU100 and QU120 are both heavy-duty crane rail profiles defined in the Chinese GB standard series for crane rails (QU70, QU80, QU100 and QU120). The number in the designation refers to the nominal head width in millimetres: QU100 has a nominal head width of 100 mm, and QU120 a nominal head width of 120 mm. The differences in cross-section drive the differences in stiffness, load capacity and price.
Cross-section dimensions and theoretical weight
| Rail type | Height (mm) | Bottom width (mm) | Head width (mm) | Web depth (mm) | Theoretical weight (kg/m) |
|---|---|---|---|---|---|
| QU70 | 120 | 120 | 70 | 28 | 52.8 |
| QU80 | 130 | 130 | 80 | 32 | 63.69 |
| QU100 | 150 | 150 | 100 | 38 | 88.96 |
| QU120 | 170 | 170 | 120 | 44 | 118.1 |
QU100 has a nominal height of 150 mm, a bottom width of 150 mm, a head width of 100 mm and a web depth of 38 mm, giving a theoretical weight of 88.96 kg/m. QU120 steps up to a height of 170 mm, a bottom width of 170 mm, a head width of 120 mm and a web depth of 44 mm, at 118.1 kg/m. The larger head, web and base sections of QU120 give it substantially higher bending stiffness and a higher load-bearing capacity per unit length of track.
Load-bearing capacity and typical applications
QU100 is specified for heavy-duty but moderate crane service: large plant overhead cranes, container yard gantry cranes and general industrial crane runways that operate at high frequency with considerable wheel pressure. Its section is sufficient for wheel loads in the common range of heavy industrial cranes and keeps steel cost and foundation load reasonable.
QU120 is designed for ultra-heavy-duty and extreme service: ultra-large port quay cranes, ladle car tracks in metallurgical plants, and other installations where wheel pressures, impact loads and fatigue cycles exceed what a QU100 runway can sustain. The heavier section also spreads the wheel load over a larger sleeper or support area, which matters on long-span crane girders.
Material and steel grade
| Steel grade | C (%) | Si (%) | Mn (%) | Cr (%) | V (%) | P (%) | S (%) | Tensile strength Rm (MPa) |
|---|---|---|---|---|---|---|---|---|
| U71Mn | 0.65-0.76 | 0.15-0.58 | 0.70-1.40 | - | - | ≤0.035 | ≤0.030 | ≥880 |
Both QU100 and QU120 are commonly rolled in high-strength steel such as U71Mn. Depending on the project, the rail head can be surface hardened or the rail can receive anti-corrosion treatment. Because QU120 has a larger cross-section, its heat treatment and installation demand higher equipment and process standards, and its construction cost is correspondingly higher. The extra cost is justified only where the duty cycle actually requires the heavier profile.
How to choose between QU100 and QU120
Selection should be based on crane wheel load, wheel spacing, operating frequency, runway span and support spacing. As a practical rule, QU100 covers the majority of heavy industrial crane runways, while QU120 is reserved for the highest wheel pressures and the most demanding fatigue duty. Confirming the wheel pressure against the rail head contact stress and the bending stress of the runway beam is the engineering method that decides the profile.
Frequently Asked Questions
What does the number in QU100 and QU120 mean?
The number is the nominal head width in millimetres: QU100 has a 100 mm head width and QU120 a 120 mm head width. The two profiles belong to the same GB crane rail series (QU70, QU80, QU100, QU120).
How much heavier is QU120 than QU100?
QU120 has a theoretical weight of 118.1 kg/m against 88.96 kg/m for QU100, a difference of about 29 kg/m. A 100 m runway therefore requires roughly 2.9 tonnes more rail when QU120 is specified.
Are QU100 and QU120 made from the same steel?
Both are typically rolled in high-strength grades such as U71Mn. The chemical composition and mechanical property requirements are defined by the applicable GB standard for crane rails, and the same grade can be specified for both profiles.
Can QU120 be used wherever QU100 is specified?
Physically yes, but it is usually uneconomical. The heavier rail increases steel cost, foundation load and the stress on supporting structures. Unless the wheel load or duty cycle demands it, QU100 is the cost-effective choice.
Do QU100 and QU120 require different rail fastenings?
The fastening system must match the rail base width: 150 mm for QU100 and 170 mm for QU120. Rail clamps, base plates and drilled hole patterns differ between the two profiles, so fastenings cannot be freely interchanged.
What processing is commonly applied to crane rails?
Typical processing includes cutting to length, drilling of fishplate holes, end grinding, and surface treatment such as painting or anti-corrosion coating. Head hardening can be specified where high wheel pressures and wear are expected.
