Wire Rope Sag Planning
Wire rope sag is the vertical drop between the support chord and the rope curve. It matters in lifting yards, temporary spans, farm gates, guide wires, safety barriers, and simple material runs. A small error can change clearance, support load, and connection stress. This calculator gives a practical estimate before detailed design.
Why Sag Changes
Sag depends on span length, unit load, and horizontal tension. Longer spans create much larger sag because length is squared in the parabolic formula. Heavier rope, ice, wind, or hanging parts increase the distributed load. Higher horizontal tension reduces sag, but it also raises end tension. The safe answer is not always the tightest rope.
Parabolic And Catenary Views
The parabolic method is common for small sag compared with span. It is fast, clear, and useful for early planning. The catenary method follows the natural curve of a flexible cable under its own weight. It becomes more important when sag is large, span is long, or precision is needed. This page shows both level support catenary results and practical parabolic values.
Unequal Supports
Many real spans have one support higher than the other. The calculator accepts support height difference. It estimates slope, low point position, and end tension. A low point outside the span means the rope falls across the full span without an internal dip. Clearance should then be checked near the lower support.
Safe Use
Always compare calculated support tension with the rope rating, fittings, anchors, posts, and clamps. Use an appropriate design factor. Add expected loads before judging clearance. Include water, dirt, ice, vibration, moving loads, and shock. Wire rope can stretch, settle, and lose strength from corrosion or broken wires.
Practical Checks
Measure span along a straight line between supports. Enter load per horizontal length. Use consistent units. Review the maximum support tension, sag from chord, rope length, and clearance note. For final work, follow local rules, manufacturer data, and qualified engineering advice. This tool helps planning, not certification. Recheck values after installation and inspection. Document assumptions, dates, and measured site conditions clearly.
Maintenance Notes
Inspect anchors often. Watch for cracked concrete, bent clips, loose turnbuckles, and worn thimbles. Replace damaged rope before using the span again.