Ascenders and Clamps Technical Tips: How to calculate mechanical advantage

Written By: Lance Piatt

©Petzl

Technical Information ©Petzl

How to calculate mechanical advantage

A mechanical advantage haul system reduces the effort required to raise a load. The mechanical advantage obtained is based on the pulley effect.

1. The pulley effect

If we consider a load suspended on a rope, the rope passing through a pulley above the user, with the user’s hand holding the rope on the other side of the pulley; any force applied to one end of the rope is transmitted to the other end of the rope, or, in this case, to the end of the rope on the other side of the pulley.

If the load weighs 100 kg, it is clear that the user must hold 100 kg on their side to hold the load. The two rope strands each exert a pull of 100 kg, so the pulley supports 200 kg.

Note: this theory is valid for an ideal pulley of 100% efficiency, which does not exist in the real world. In reality, pulley efficiencies range from about 50 % to 98 %.To simplify calculations, this discussion is limited to ideal pulleys.

2. Calculating mechanical advantage in practice

The efficiency (E) of a haul system indicates the force multiplier factor that you can exert on the rope. For example, if you are able to pull 20 kg maximum on a rope with your bare hands, a 3:1 haul system will enable you to raise a 60 kg mass. This reduction is obtained by increasing the amount of rope to be pulled: to raise a mass 1 meter with a 3:1 system, 3 m of rope must be pulled.

The efficiency (E) of a haul system may be calculated by adding the effects of each pulley.

Start by drawing a simple diagram of the system, then show the pulling force F that the hand applies to the rope.

Transmit the force F along the rope by adding the effects of each pulley.

When multiple rope strands are attached to the load (double pulley, rope clamp…), add the forces exerted by each strand.

Note: the advantage of a 3:1 system is its ease of setup and that it can easily be converted to a complex system (7:1) with one additional pulley and some cord.

 

[thrive_lead_lock id=’56688′]Hidden Content[/thrive_lead_lock]

 

Peace on your Days.

Lance

Categories
Facebook
Twitter
LinkedIn
Email

About The Author:

Related Posts

10 thoughts on “Ascenders and Clamps Technical Tips: How to calculate mechanical advantage”

  1. 393997 13995Aw, this was a really nice post. In concept I wish to put in writing like this moreover ?taking time and precise effort to make an exceptional post?but what can I say?I procrastinate alot and undoubtedly not appear to get one thing done. 387398

  2. 233875 974923Right after study a couple of with the blog posts on your own internet site now, we actually like your way of blogging. I bookmarked it to my bookmark internet internet site list and are checking back soon. Pls consider my web-site likewise and make me aware if you agree. 194330

  3. 529045 320596Wow, cool post. Id like to write like this too – taking time and real effort to make a good article but I procrastinate too considerably and never seem to get started. Thanks though. 649650

  4. Erotik18 film; film izle erotik konulu; film izle esmer
    18; Film sex Türkiye; film18sex; fılmı seksı doktor; filmizle88 or; FrmRed com sex turk film; hemşire
    sexk izle; hemşire sexs; her türlü konulu seks filmleri;
    her turlü konulu sex erotik; hizli doktor seksizim; hızlı
    doktor yerli; hizli turk seks filimi; konul erotik film.

  5. After working an appetite, they head into to town in search of a
    cool destination to eat. After checking out town a little bit,
    they head over to the pool. There, Kira
    twerks in the water as other tourists watch in awe. By now it was
    the end of day one, and there’s only one thing needed to
    be done to wind down.

Leave a Comment

Your email address will not be published.