A single fixed pulley changes hauling direction but has ideal mechanical advantage 1:1. With a selected efficiency η, the reference effort is load force divided by η; this does not size rope, sheave, anchors or lifting equipment.
Fixed Lifting Pulley Force Reference
Explore fixed-pulley effort and bend-ratio arithmetic with a continuous equal-travel rope path.
Equation Used
- The pulley is fixed and the ideal mechanical advantage is one.
- The rope is continuous and inextensible in the visualization.
- The selected efficiency is applied as one overall scalar.
- Dynamics, shock, terminations, wear, strength, ratings and safety factors are excluded.
The selected efficiency is a simple overall reference; D/d is reported without a pass/fail claim.
Fixed sheave and continuous rope
The animation shows one supported sheave and one continuous rope connecting the load side to the haul side. Load rise and haul-end descent remain equal in the ideal inextensible-rope geometry.
What the calculator determines
Select load mass, efficiency, rope diameter and sheave diameter. The calculator reports reference effort in kgf and newtons, ideal 1:1 mechanical advantage and selected D/d bend ratio.
Fixed-pulley reference
Effort kgf = W/η; effort N = 9.80665W/η; ideal MA = 1; bend ratio = D/d.
Selected-input arithmetic
A 50 kg load at 100% selected efficiency requires a 50 kgf reference effort, about 490 N, before all unmodeled safety and dynamic factors.
Force arithmetic only
The reference excludes acceleration, shock, rope mass, stiffness, groove friction, bearing friction distribution, fleet angle, termination efficiency, wear, fatigue, anchor loads, rated capacity and safety factors. D/d is reported without declaring acceptability.
Questions
Does a fixed pulley multiply force?
No. Its ideal mechanical advantage is one; it primarily changes direction.
Is the D/d result a pass/fail check?
No. Acceptable bend ratio depends on the actual rope and manufacturer guidance.
Primary safety references
- OSHA 29 CFR 1910.179 — rated-load, sheave-groove, guarding, lubrication and manufacturer-rope requirements for overhead and gantry cranes.
- OSHA ropes, cables, slings and chains guidance — rope/sheave bend, surface condition, guarding and manufacturer-use boundaries.
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