Final answer:
Cable come- alongs use pulley or lever systems to provide a mechanical advantage for moving heavy loads, with the mechanical advantage determined by the number of ropes supporting the load.
Step-by-step explanation:
Cable come- alongs are mechanical devices that employ pulley systems or lever systems to move heavy loads. These systems provide a mechanical advantage by allowing the user to apply a relatively small force to move a much larger force. The basic mechanism involves either moving a load over a short distance using a screw, similar to lifting a car with a jack, or using pulleys where the load is supported by several cables, each contributing to the total lifting force.
For pulley systems, the mechanical advantage (MA) can be calculated by counting the number of ropes that support the load. If one cable supports the load, the MA is approximately 1, and you need to pull 1 meter of rope to lift the load by the same distance. For systems with more cables, the distance you must pull the rope increases accordingly, but the force required decreases proportionally.