We are often asked to "calculate a sling" without being told what it is for. It's not a detail: the same steelwork is checked differently if it goes into a lift or into a lifting platform.
Two directives, two standards
A lift falls under the Lifts Directive 2014/33/EU: it is designed to EN 81-20and calculated with EN 81-50. A lifting platform up to 0.15 m/s, falls under the Machinery Directive and follows EN 81-41.
Certification and technical file change. For us, above all, load cases and coefficients change.
What changes for the sling
- Load cases. EN 81-50 wants operation, safety gear and unbalanced load. EN 81-41 has its own cases: lower loads and speeds, more attention to eccentric load and deformation, because the car is often open.
- Coefficients. Allowable stresses and safety factors don't match: an upright that passes under one standard doesn't necessarily pass under the other.
- Guide rails. For lifts we check them for bending and buckling with EN 81-50. For platforms EN 81-41 has its own criteria, with separate deflection limits.
- Safety gear. Allowed devices and decelerations change, and so does the dynamic load on the sling.
Why it matters to you
Many manufacturers use the same slings for both products. That's fine, as long as the sling is checked against both standards and each technical file refers to the right report.
In the families we design, like the XF, the double check is included. Doing it up front costs little, doing it later costs a lot.
What we deliver
One report per standard, with load cases, stress and deformation maps, buckling of the uprights and comparison with the limits. If you already have the 3D, we start from there: it's all on the calculation page.