2:1 Piggyback System

“The advantage of using a piggyback system (sometimes called a "pig rig") is that the pulley doesn't need to be attached to the load (which might be a long way from the anchor). This enables rescuers to use less rope and makes it less likely that the pulley will get caught on the terrain when raising. The disadvantage of a piggyback system is a little additional complexity. Piggyback systems also need to be "reset"
It is easy to confuse the 2:1 piggyback system shown here with a 3:1 system. Both systems have the classic "Z-rig" appearance. Notice, however, that the end of the rope on 2:1 systems is attached to the anchor whereas the end of the rope on 3:1 systems is attached to the load. Whether the end of the rope connects to the anchor or to the load is a subtle difference between mechanical advantage systems that have an even number (e.g., 2:1, 4:1, 6:1, etc) and systems that have an odd number (e.g., 1:1, 3:1, 5:1, etc). The end of the rope is attached to the anchor on systems with an even-numbered mechanical advantage ratio.”