Mechanical Advantage Flashcards
What is mechanical advantage (MA)?
Force-amplifying effectiveness using pulley systems to increase the rescue team’s ability to carry out a safe rescue.
MA measures how much a rope and pulley system leverage the force applied to it.
What are the two types of mechanical advantage systems used by QFR?
- Simple system
- Compound system
What is a simple system in mechanical advantage?
A system that involves the load line passing through all pulleys and devices with the rope moving from load to haul team.
This system is effective for reducing physical effort to move a load.
What characterizes a compound system in mechanical advantage?
A compound system consists of a simple system pulling on another simple system.
What is a Z rig?
The most used hauling system that creates a 3:1 MA system using the tail of the main line through a belay device.
It is classified as a simple system.
What is the in-line method of attachment?
A method that uses the tail of the line to attach an MA system that compounds the original system.
What is the bolt-on method in mechanical advantage?
A method built separately from the main line that can be attached to the load line, which can be either simple or compound.
What factors influence the mechanical advantage of systems?
- Equipment
- Friction
- Load weight
- Number of persons available
What is ideal mechanical advantage (IMA)?
Theoretical MA, such as 2:1, 3:1, etc.
What does practical mechanical advantage (PMA) consider?
Friction loss throughout the hauling system.
How do you calculate pulling force with a mechanical advantage of 2:1 for a 100kg load?
Pulling force = load ÷ effort = 100kg ÷ 2 = 50kg.
What is a direct haul?
A haul using physical force only, requiring a specific number of persons based on the load weight.
What is the maximum efficiency of a simple system?
6:1.
MA greater than 6:1 will create high levels of friction due to increased equipment.
How does a compound system differ from a simple system?
It involves two simple MA systems joined together.
What are the advantages of a compound system compared to a simple system?
- Less equipment
- Less friction for greater MA
What is the Z-rig system used for?
The quickest and easiest in-line method for creating a mechanical advantage.
What is the primary function of a bolt-on MA system?
To be constructed independently from the main line and attached when needed for maximum gain.
What is the role of a moving pulley in calculating mechanical advantage?
It adds the tensioned lines together to calculate MA, effectively doubling the force.
What is the significance of counting travelling lines through moving pulleys?
It helps identify the mechanical advantage by counting each line under load that is travelling through moving pulleys.
What does counting units of tension involve?
Starting from the haul end of the rope and considering the effect of moving and fixed pulleys on the tension.
What happens to the tension when the line travels through a moving pulley?
The units of tension double at the connection point of that pulley.
How is mechanical advantage calculated in a compound system?
Isolate each bolt-on and/or in-line system, count the individual MA, and then multiply those systems together.
What is a dead leg in a mechanical advantage system?
A rope in the system that does no work and could be cut/removed with no effect on the system.
What is the total mechanical advantage (MA) when T4 and T2 are added at the rigging plate?
6:1
This is calculated by considering the contributions of T4 and T2 in the pulley system.
