Rope rescue rope grabs, and other tools, to raise, or haul, a load up a vertical section, or across a gully or canyon. Pulleys systems are used in conjunction with the rope, rope grabbing devices, i.e.: Prusiks, or mechanical grabs, to capture the progress made during the lift. Since pulley systems are generally short in length, they are used in conjunction with a progress (raise) capturing technique, and a long rope; and a backup safety or belay. This specialized equipment is used to reach the subject(s) and safely recover them. These techniques are subdivided, and are sometimes the techniques and equipment are
Block and tackle each of the parts of the rope must be "F/n." This means the input force on the rope is "F"="F/n." Thus, the block and tackle reduces the input force by the factor "n." Ideal mechanical advantage correlates directly with velocity ratio. The velocity ratio of a tackle is the ratio between the velocity of the hauling line to that of the hauled load. A line with a mechanical advantage of 4 has a velocity ratio of 4:1. In other words, to raise a load at 1 metre per second, the hauling part of the rope must be pulled at 4