Pulley Systems

 Pulley Systems - Definitions Sheave is the grooved wheel that the rope runs on The larger the diameter of the sheave, the less friction and the more efficient Usually made out of nylon or aluminum

 Pulley Systems - Definitions Side Plate can have holes or not, and can swivel or not Larger top attachment point allows for the use of larger or multiple carabiners

 Pulley Systems - Definitions Bearing or Bushing are the points where the axle meets the other parts of the pulley Bearings are more efficient than bushings This pulley with bearings has an efficiency of 216% and with bushings it is 198%

 Pulley Systems - Definitions Becket is a lower attachment point between the two sheaves Can be used to attach a rope or a second pulley

 Pulley Systems - Definitions PMP or Prusik Minding Pulley has side plates that help keep a prusik knot from being jammed in the pulley The prusik knot has to be wider than the distance between the side plates

 Pulley Systems - Definitions Directional is a pulley that is between the pulley system and the load Does not add any MA to the system

 Pulley Systems - Definitions Change of Direction is a pulley on the anchor that is closest to the haulers Does not add any MA to the system

 Pulley Systems - Definitions Pr is a ratchet prusik which is a type of progress capture device

 Pulley Systems - Definitions Ph is a haul prusik for attaching to the rope

 Pulley Systems - Definitions Collapsed Pulleys or Two Block is when the system can not be made any shorter

 Pulley Systems - Types Simple Compound is any combination of two or more simple pulley systems acting on each other

 Pulley Systems - Types Simple Compound (multiple) Complex does not follow any of the rules for a simple or compound pulley system

 Pulley Systems - Types Compound Pulley System Rules  Total MA equals the product of each simple pulley system’s MA (2:1 acting on 3:1 = 6:1)  The greatest MA created using the fewest pulleys comes from 2:1 acting on 2:1 (2:1 x 2:1 x 2:1 x 2:1 = 16:1)  Having the greater MA system acting on the lesser means less resets  Traveling pulleys move toward anchors, but not necessarily at the same speed

 Pulley Systems - Types Complex Pulley System Rules  Determining total MA requires the use of the “T” method, which can also be used for simple and compound systems  Systems that have pulleys moving towards the load are complex

 Pulley Systems – “T” Method Assumes no loss from friction or ideal mechanical advantage

 Pulley Systems – “T” Method Assumes no loss from friction or ideal mechanical advantage Assumes that the rope angle through a pulley is very close to 180 degrees