VDE 0250-814

To understand reeling cables and why the ÖLFLEX CRANE NSHTÖU design is fundamentally different from standard control or power cables, let me start with a basic distinction about how cables experience mechanical stress. When we discussed drag chain cables in previous technical guides, we focused on cables that bend repeatedly in a predictable path—the cable enters the chain at one end, navigates tight curves, and exits the other end. The stress is primarily bending stress, and the cable’s design is optimized for flexing along a fixed path millions of times. Reeling cables experience a completely different mechanical environment. A reeling cable is wound around a rotating drum, and as the drum rotates, the cable either winds onto the drum (spooling) or unwinds from the drum (unreeling). This seemingly simple mechanical action creates a unique set of stresses that standard cables cannot tolerate. First, imagine the cable as it winds onto a rotating drum. The first wrap of cable lies directly against the drum surface. The second wrap lies on top of the first wrap. The third wrap lies on top of the second wrap. This layering continues until the drum is completely spooled. Now here is the critical insight: cables on the outer layers of a spooled drum experience completely different mechanical stress than cables on the inner layers. A cable on the inner layer, wrapped tightly against the drum, experiences primarily circumferential compression and bending. A cable on the outer layer, wrapped loosely over all the inner layers, experiences tension (pulling force) as the drum rotates. More importantly, as the outer-layer cable unwinds, it must rotate to accommodate the unwinding motion. This rotation creates torsional stress—twisting forces that attempt to rotate the cable around its central axis. Standard control cables or drag chain cables are not engineered to tolerate torsional stress. They fail when subjected to this twisting motion, typically through a mechanism called the corkscrew effect where the cable’s multi-conductor core separates and twists relative to the outer sheath. The ÖLFLEX CRANE NSHTÖU cable is specifically engineered to prevent this failure through sophisticated mechanical design including a supporting braid with Aramid fibers that maintains conductor bundle cohesion even during intense torsional stress. This is why the distinction between standard cables and specialized reeling cables is not merely academic—it is the difference between equipment that functions reliably for years versus equipment that experiences cable failure every few months.