There are two types of patio umbrella mechanisms available: pulley and crank.
Pulley umbrellas have the simplest type of mechanism and rely on your strength to pull down on a rope to raise the ribs of the frame. The rope is then tied or anchored to the central pole to secure the umbrella in place.
Crank style mechanisms use a winding handle to open the umbrella, which automatically locks in place. This is a more convenient option found in high-end umbrellas and larger models.