Pulley cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. Hero of Alexandria identified the "pulley" as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another. A set of pulleys assembled so that they rotate independently on the same axle form a block. Two blocks with a rope attached to one
Cargo hook (helicopter) metal at the bottom of a cargo hook that supports the load. Usually it has a curved, narrow end which is used to load a ring, rope, or net onto the hook. The keeper is the locking, spring-operated mechanism that keeps the load from sliding off the load beam during transport. The attach point attaches the hook to the belly of the helicopter, swing system, or longline. The following table includes a list of helicopter models that are designed to carry underslung loads. Cargo capacities provided reflect the airframe manufacturer's specifications; when put into practice the actual maximum load capacities