Written By: Lance Piatt

Determining mechanical advantage using the T-Method is really the guiding method to determine the “ideal mechanical advantage” or IMA.  However, note… this method doesn’t take into consideration the friction problems or coefficient of rope bending or turning on metal.

“A force created through mechanical means including, but not limited to, a system of levers, gearing or ropes and pulleys usually creating an output force greater than the input force and expressed in terms of a ration of output force to input force” is mechanical advantage (MA).  This is NFPA’s definition.

“The advantage gained by the use of a mechanism in transmitting force; specifically the ratio of the force that performs the useful work of a machine to the force that is applied to the machine”  Merriam Webster

“What’s the heaviest thing you can lift? Do you think you could lift a whole car? Or a grizzly bear? Probably not by yourself – but if you had a mechanical advantage, you could! A mechanical advantage is the amount of help you can get from using a machine to do something instead of just doing it with purely your own strength.” Study.com

Personally, I like #3.  Why? The terms “input and output” are nebulous to many.  Is this shirking the accountability with have to upscale the process and not allowing a “dumbing down” of definitions.  Not at all.  In fact, it has been shown that smaller scope for a limited time allows for a much larger scope faster and with exponentially better results.

In the following video, we are looking at a “progression” starting from a simple 3:1 to a complex 5:1 and finishing with a compound 9:1.  I thought this would be a very cool example of combining all three types of system with a fluid set up.  Also note, I built these and hauled the single load (170 lbs / 77 kg) by myself.  Why is this important?  I wanted to show you don’t need 3 people on a haul to get something done.  One is just fine… it only requires a tuned mechanical advantage system to get the job done.

A Simple Rope Mechanical Advantage System is a rope system containing a single rope and one or more traveling pulleys attached to the load.  Everything moves at the same rate.

A Compound Rope Mechanical Advantage System is a combination of individual rope mechanical advantage systems.  Generally a Simple System pulling on a Simple System.

A Complex Rope Mechanical Advantage System is combination of rope mechanical advantage system components that is either Compound nor Simple. Generally, the systems move at different rates.

I want to encourage you here.  The vast amount of you who just finished this article (80% of you) just got got a promotion in your understanding of pulley systems and mechanical advantage.  Why… we gave three definitions of mechanical advantage as it pertains to “haul systems and rope rescue”.  80% of the people chose #2 or #3 as the definition that made most sense.  Option #1… well, only 10% understood the definition and could apply it.

Another reason for the quick upscale is that there were three videos describing systems in three different ways.  Remember, auditory, visual and kinesthetic learning?  Not everyone learns the same way nor at the same rate such.

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