Peak Rescue Institute: Team Based Lower, Pick-Off, to Raise | Block and Tackle

Written By: Lance Piatt

Team Based Lower Pick-Off With adequate personnel for rigging and good communication, the team based lower pick-off is the method of choice for extricating and uninjured victim. The team based pick-off method is for patients… •Stranded without a rope on ledges or platforms •Suspended from climbing rope or safety tethers. •Patients needing extrication •Overly aggressive patients. The advantages… •Hands Free •Can be raised and or lowered •Knot passing is much easier A line transfer may be performed to transfer the patient’s weight to the rescuer’s line. Since patients weight may vary greatly, as may the size of the rescuer, the most effective manner in which to perform this task is a pre-set “Set of Fours”, but in this video, a simple 2:1 MA (two to one mechanical advantage) is used (due to the slope of the terrain. The CMC MPD is used on both the main line and belay line. A slight loss in efficient is managed by the time saved in switching from lower to raise. This is a huge benefit for both the team and the patient. For the purpose of lifting or moving heavy loads a block and tackle system consists of two or more pulleys connected by one common cord or rope that is threaded between the pulleys. As most know, pulleys are simply wheels on axles designed to assist or direct movement of the rope along the grooved circumference of the wheel. One pulley alone can be utilized to lift loads and apply forces to transmit power, but incorporating multiple pulleys into a system decreases the amount of applied force required to transmit the power to move the load. A pulley, also known as a sheave or drum, most commonly has a groove on the wheel’s outside edge along the perimeter of the wheel between two flanges around the pulley’s circumference. The cord or rope is the drive element of the pulley or pulley system. When the rope in a pulley is pulled upon, the force applied to the rope compresses it against and into the V groove between the flanges of the pulley wheel creating sufficient friction to move the wheel, rotating the pulley wheel around its axle. Multiple pulleys can be configured to form a block and tackle system for the purpose of providing a mechanical advantage to apply large forces in order to lift or move the heavy load more easily than with one pulley. Two pulleys together in a system form blocks. Blocks are arranged in such fashion that one moves with the load while the other is in a fixed position. The assembly of a set of two blocks with the rope threaded around the respective pulleys is called tackle. The rope threaded around the pulleys is referred to as reeving. The rope or cord that is reeved through the pulleys provides mechanical advantage. Mechanical advantage amplifies the force applied to the rope allowing for the moving or lifting of the load with less initial, original force. The end result is a system of pulleys that moves and lifts loads more easily while less force is applied when pulling upon the cord or rope.

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