Free Pulley System Calculator
Calculate the mechanical advantage and required effort force for a compound pulley system.
Actual Effort Force
277.8 N
Actual Effort Force vs Number of Supporting Rope Segments
Compound Pulley Mechanical Advantage
A pulley system reduces the effort needed to lift a load by distributing the weight across multiple rope segments.
Formulas
Ideal MA = number of supporting rope segments (n)
Effort = W / (n x efficiency)
Rope travel = n x lift distance
The trade-off is that you must pull n times more rope to lift the load a given distance. Friction in each pulley sheave reduces the actual mechanical advantage.
Example Calculation
A 4-part block and tackle lifting 1000 N at 90% efficiency.
- 01Ideal MA = 4
- 02Ideal effort = 1000 / 4 = 250 N
- 03Actual effort = 1000 / (4 x 0.9) = 277.8 N
- 04Rope travel = 4 m of rope per 1 m of lift.
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