Pulleys are used for raising equipment, and for making haul systems in a rescue situation. Some of them can be combined with a rope clamp to facilitate maneuvers; others allow movement along rope or cable.
Two factors determine a pulley s efficiency:
Sheave size: the larger the sheave diameter, the higher the efficiency
Bushings and bearings: - self-lubricating bushings are efficient, but they must be regularly maintained - sealed ball bearings are very efficient, and they do not require any maintenance
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