Tower Safety Rigging Lab

2:1 Mechanical Advantage Simulator

See how two supporting rope legs reduce the haul force while the upper and lower pulleys develop their own tower reactions.

NORMAL — Training Range
How the system works: Two rope legs support the moving pulley. Pulling approximately 250 lb can lift a 500 lb load before friction and geometry losses.
Tower Safety 2 to 1 mechanical advantage drop-loop rigging arrangement
Live Tower-Leg GeometryDistance between tower legs changes this analysis triangle—not the top-to-heel pulley spacing.
Leg spacing 10 ftSupport leg 10.0 ftLoad line 20.0 ft
Fixed Anchor → Moving Pulley / Load → Top Pulley → Lower Redirect Pulley → Hoist
Live rope (orange = normal) Pulley reaction Advanced Fx / Fy

Start Here — Main Inputs

Angle Risk MonitorNORMAL — 45°
Normal operating geometry.
Advanced Setup & Equipment Ratings

Main Results

Required Pull Force0 lb
Top Pulley Load0 lb
Heel Pulley Load0 lb
Advanced Forces & Geometry
Mechanical Advantage0.00×
Actual MA after Loss0.00×
Moving Pulley Resultant0 lb
Moving Pulley Side Load0 lb
Upper Fx / Fy0 / 0 lb
Lower Fx / Fy0 / 0 lb
Combined Tower Reaction0 lb
Combined Fx / Fy0 / 0 lb
Included Rope Angle θ0°
Vertical Force (Fy)0 lb
Horizontal Force (Fx)0 lb
Load Line Length0 ft
Support Leg Length0 ft
Upper Pulley Included Angle0°
Lower Pulley Included Angle0°
Rope WLL Utilization0%
Upper WLL Utilization0%
Lower WLL Utilization0%

Live Teaching Warning

NORMAL — Forces are within the selected training limits.

Monitor geometry, equipment ratings, load control, and wind conditions throughout the lift.

How the Engineering Math Works

Engineering force model: Fy(N) = Gross Load × 9.8 × cos(θ/2), Fx(N) = Gross Load × 9.8 × sin(θ/2), and pounds = newtons × 0.225. For angles below 90°, Load Line = 2 × Support Leg Length and Support Leg Length = tower-leg distance × cot(θ).

Simulator lifting calculation: The moving-pulley support factor is 2 × cos(θ/2). Required haul tension is the dynamic design load divided by that support factor and the entered system efficiency. This is shown separately from the engineering Fx/Fy analysis.

Pulley reactions: Each fixed pulley reaction remains the vector sum of the two equal rope tensions entering and leaving that pulley. Top and heel placement is intentionally limited to close, same-leg geometry; their visual heights do not alter the supplied engineering reference formulas.

Important: The reference labels Gross Load in pounds while multiplying by 9.8 before converting newtons back to pounds. V12.8 preserves that supplied convention for comparison rather than silently changing it. This educational model does not replace a site-specific engineered rigging plan, manufacturer load chart, or Qualified Engineer review.