Petzl Mini Prusik Pulley

The Petzl Mini Prusik compact pulley is an incredibly efficient and lightweight option for constructing progress capture systems.

Features

• Specially designed side plates accommodate a Prusik friction hitch in progress capture systems.
  
• The sheave is mounted on sealed ball bearings, ensuring exceptional efficiency.
  
• Its compact and lightweight design enhances portability and ease of use.

Specifications

Technology

Technical Notice

• Download the PDF : technical-notice-MINI-GEMINI-2 - 1.59 MB
• Download the PDF : technical-notice-COMM_POULIES_1 - 1.12 MB

Declaration Of Conformity

• Download the PDF : UE-Declaration-P59A-AN-Mini - 0.64 MB
• Download the PDF : UKCA-Declaration-P59AX-MINI - 0.54 MB

Tips for maintaining your equipment

• Download the PDF - 2.72 MB

Inspection

PPE inspection procedure

• Download the PDF - 1.09 MB

PPE checklist

• Download the PDF - 0.20 MB
  

Technical Content

Pulley System Efficiency Tests with Maestro, I'D S, Pro Traxion, Rollclip...

There can be a big difference between the theoretical efficiency of a pulley system and its actual efficiency. Here are test results from the Petzl lab.

1. Efficiency depending on the device used at the head of the system.

The force required to raise a 100 kg mass was tested under several configurations with different devices at the head of the system and with ropes of various diameters.

Test Protocol:

• Ropes tested: RAD LINE 6 mm, 7 mm cord, SEGMENT 8 mm, PUSH 9 mm, CLUB 10 mm, PARALLEL 10.5 mm, AXIS 11 mm, VECTOR 12.5 mm.
• Measurements were made with a constant pull rate of 1.5 meters/minute, on new devices and ropes.
• The results are given for information only; in the field there are numerous variables to take into account (position of haul system elements, rope diameter and construction, hauling speed, hauling smoothness, the haul load...).
  
  

Note: Pulley efficiency ratings in the Instructions for Use are based on values measured with a simple 1:1 directional. Hauling efficiency F = xx M is the value obtained with the smallest compatible rope diameter for the device. The pulley efficiency expressed in % is calculated from this value. Efficiency is always less than 100%, which is the efficiency of an ideal pulley (impossible in reality). Example for MAESTRO S: F = 116 M, efficiency = 86%

2. 3:1 Haul system efficiency depending on the redirect point used

Using Pulleys with Small-Diameter Rope or Cord

As part of their certification as PPE, Petzl pulleys are compatible with ropes greater than 7 mm in diameter. The use of thinner cords may be possible.

The EN 12278 standard does not require setting a minimum diameter limit for compatibility with pulleys. However, Petzl pulleys show compatibility only with diameters greater than 7 mm, regardless of the type of cordage (cord, dynamic rope, low-stretch rope, static rope...).

Using cords in pulleys is common: accessory cord in a double mariner pulley system, various haul systems, hauling or rescue with PUR LINE and RAD LINE...

Some pulleys have a space between the sheave and the side plates, where a thin cord can jam in case of an off-axis pull. So they are not compatible with small-diameter cordage. Some pulleys can be used with small-diameter cords, except in certain cases (see table below). The smaller the cordage diameter, the greater the risk of derailment, especially with diameters less than 5 mm. Always heed the use and strength limits of the cord, indicated in its Instructions for Use and/or the manufacturer's directions.

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.

1:1 Haul System

2:1 Haul System

3:1 Haul System

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.

4:1 Haul System

5:1 Haul System