Two Standards, Two Design Philosophies
DIN 536 A-series rails from A45 to A150 and QU series rails from QU70 to QU120 are both crane rails, but they follow different standards and different design philosophies. The DIN 536 series is the European standard, while the QU series follows the Chinese standard YB/T 5055. Both naming conventions use the head width in millimeters, so A100 and QU100 both have a 100 mm head, but the rest of the proportions are entirely different.
Geometric Profile: Squat vs Tall
The most significant physical difference is the geometry. The DIN A-series is designed low to the ground with a massive base and a thick web. This squat design prioritizes lateral stability and resistance to prying forces. The QU series has proportions closer to a traditional railway rail: it is taller, has a narrower base, and a thinner web. The QU design provides more vertical bending strength but less lateral stability.
| Parameter | DIN A100 | QU100 |
|---|---|---|
| Head width | 100 mm | 100 mm |
| Base width | 200 mm | 150 mm |
| Rail height | 95 mm | 150 mm |
| Web thickness | 60 mm | 38 mm |
| Nominal mass | 74.3 kg per meter | 88.96 kg per meter |
Because of their different shapes, the weight per meter and the distribution of that mass differ. The QU100 weighs 88.96 kg per meter, making it heavier than the A100 at 74.3 kg per meter. However, the A100 mass is concentrated in the wide base, creating a much lower center of gravity. The A100 spreads less total weight over a wider footprint, which is often better for protecting the top flange of an overhead steel girder.
The DIN 536 A-Series Range
| Profile | Head mm | Height mm | Base mm | Web mm | Mass kg per meter |
|---|---|---|---|---|---|
| A45 | 45 | 55 | 125 | 24 | 22.10 |
| A55 | 55 | 65 | 150 | 31 | 31.80 |
| A65 | 65 | 75 | 175 | 38 | 43.10 |
| A75 | 75 | 85 | 200 | 45 | 56.20 |
| A100 | 100 | 95 | 200 | 60 | 74.30 |
| A120 | 120 | 105 | 220 | 72 | 100.00 |
| A150 | 150 | 150 | 220 | 80 | 150.30 |
The QU Series Range
| Profile | Head mm | Base mm | Height mm | Web mm | Nominal Mass kg per meter |
|---|---|---|---|---|---|
| QU70 | 70 | 120 | 120 | 28 | 52.80 |
| QU80 | 80 | 130 | 130 | 32 | 63.69 |
| QU100 | 100 | 150 | 150 | 38 | 88.96 |
| QU120 | 120 | 170 | 170 | 44 | 118.10 |
Material Grades and Selection Guidance
The DIN A-series is typically supplied in European tensile grades 700, 900A, and 1100, with 900A being the most common for a good balance of hardness and weldability. The QU series is typically supplied in Chinese grades, most commonly U71Mn, a high-carbon high-manganese steel with a tensile strength roughly equivalent to grade 900A at about 880 MPa. In both families, the steel chemistry is selected to prevent head mushrooming and rolling contact fatigue.
Choose the DIN A-series when lateral stability, low center of gravity, and protection of the girder flange are the priority, especially for high-speed gantry cranes and international port projects. Choose the QU series when the project is designed around the Chinese standard, when more vertical bending strength is needed, or when local supply chains favor the YB/T 5055 profile. The two series are not interchangeable on an existing runway without significant modification.
Frequently Asked Questions
Can I replace a QU100 rail with an A100 rail on the same runway? No, not without significant modification. The A100 is 55 mm shorter and 50 mm wider at the base than the QU100, so the runway height and all fastening positions must be adjusted.
Which series is better for high-speed gantry cranes? The DIN 536 A-series is often preferred because its low center of gravity and thick web provide better stability against lateral hunting forces during rapid acceleration and braking.
Is the hardness of U71Mn different from grade 900A? They are very similar in performance. Both provide a Brinell hardness of about 260 to 300 HBW, the industry standard for preventing head mushrooming under heavy wheel loads.
Are the rail heads of A100 and QU100 the same width? Yes, both have a nominal head width of 100 mm, so they can accommodate the same crane wheels, but the support beneath the head is very different.
Which series is more economical for long port tracks? The A-series uses less steel per meter than the QU100 at 74.3 kg versus 88.96 kg, which can save material cost, but the specialized fastening clips for the wider A-series base may cost more.
Do both series support welded joints? Yes, both can be joined by aluminothermic or flash-butt welding to create a continuous crane runway, with proper preheating and cooling control.
