Mechanical advantage is a concept in basic physics whereby the force produced is greater than the force applied. The applied force is exerted over a greater length than the movement of the load. Examples:
- A 2:1 system produces double the force applied. The force is applied for double the distance that the load is moved.
- A 3:1 system produces triple the force applied. The force is applied for triple the distance that the load is moved.
The difference between the actual mechanical advantage and the theoretical mechanical advantage can be significant, due to the loss in the system. See video:
Here is an example where mechanical advantage works against us. In a Basal Anchor SRT system, the tree crotch is subject to the forces of mechanical advantage, whereby it must sustain approximately double the weight of the climber. Rationale:
- The climber’s full weight is loaded on one side of the rope and fully absorbed by the crotch.
- The tension on the other side of the system is also equal to the climber’s weight.
- The tree crotch supports double the load.