Mountain Rescue Aspen Mechanical Advantage Mechanical Advantage Simple Simple pulley ‐ One con9nuous rope flowing back and forth alterna9ng between the pulleys on the load and anchor(s). All pulleys at the load side, travel towards the anchor at the same speed. All pulleys at the anchor side remain sta9onary. • 
– 
– 
– 
– 
If the 9ed end of the rope is at the anchor , the mechanical advantage will be an even number (2:1, 4:1) If the 9ed end of the rope is at the load, the mechanical advantage will be an odd number (1:1, 3:1, 5:1) If the last pulley in the system is at the anchor (fixed), it will not add MA, but will change the direc9on of pull The MA of a simple system is determined by coun9ng the number of ropes under tension at the load side of pulley Anchor
Anchor
Anchor
Anchor
. . Not showing load capture
2:1cd 2:1 Anchor
Anchor
Anchor
. . 4:1 Anchor
. . 1:1cd . . 3:1 . . 5:1 Mechanical Advantage Compound Compound pulley ‐ One simple pulley system pulling on another simple pulley system. The traveling pulleys travel towards the anchor at different speeds. Compound pulley provide greater MA than simple systems for the same number of pulleys. • 
– 
– 
The MA of a compound system is determined by mul9plying the MA of each simple pulley Longer throw distances per reset can be achieved by posi9oning the anchor pulleys (closest to the hauler) far enough back to allow each simple pulley system to collapse at the same 9me. Anchor
Anchor
Anchor
Anchor
. . Not showing load capture
4:1 Anchor
Anchor
. . 6:1 . . 9:1 Mechanical Advantage Pre‐rigged Pulley systems can be rigged either by using the mainline or using a separate rope “ac9ng on the mainline” • 
Anchor Anchor
. . Assume we are 9ed off 3:1
Not showing load capture
Anchor
Anchor
Anchor
Anchor
. . . . 4:1 piggy‐back (Amsar) 4:1 simple We will see this when rigging a kootenay highline Mechanical Advantage High Angle & Scree Generally the knot on the mainline is a[ached to a rescuer or a li[er for high angle and scree uphauls with a pulley(s) located at the anchor therefore we will be thinking about simple or compound systems; (3:1, 6:1 or 9:1). The excep9on will be if we decide to a[ach a MA to a main line and the excep9on could be (4:1) • 
• 
Anchor
Anchor
. . 3:1 Not showing load capture
Anchor
Anchor
Anchor
. . 6:1 . . 9:1 Mechanical Advantage Snow Snow up hauls generally have the knot 9ed at the anchor with a pulley located on the li[er, therefore, we will be thinking about 2:1, 4:1 and 6:1. • 
Anchor
Anchor
Anchor
. . 2:1 Not showing load capture
. . 4:1‐s Anchor
Anchor
Anchor
Anchor
. . 4:1‐c . . 6:1