# The 4:1 Pulley System

This pulley system provides a 4:1 mechanical advantage. The user is required to apply a force of 25kg to raise this 100kg load, for every 4 metres of rope that the user pulls through the pulley system the load will only be raised by 1 metre.

If we count the amount of ropes that are actually supporting or applying effort on the load, and then divide the loads weight equally between them we should easily be able to calculate the overall mechanical advantage of the pulley system.

In this scenario there are four sections of rope supporting and applying effort to the load. So the loads weight (100kg), divided by the amount of supporting sections of rope (4), should result in each rope supporting one quarter (25kg) of the loads total weight. The rope is then returned to the user via a redirect (pulley D) who applies 25kg of effort to raise the 100kg load.

## Vector Forces

Vector forces become apparent whenever there is an internal angle greater than 0° between two or more rigging components or anchorage points. For ease of…

## Angular Vector Forces

Angular vector forces occur when ropes are passed through a deviation or a directional pulley. Dependent on the angle created, this can have a multiplying…

## Fall Factors

A fall factor is a simple representation of the severity of a fall. It can be used to evaluate the potential loadings exerted on the…

## The 1:1 Redirect Pulley System

In the illustration to the right we have a rope attached to a load weighing 100kg. The rope has been passed through a pulley which…

## The 3:1 Pulley System

Here we have a 3:1 mechanical advantage. First one end of the rope is attached directly to the load, this is then passed around an…