http://www.mercurymarine.com/uploads/images/1145/sideView.jpgWhat you see here out front are "Tilt" cylinders. Used primarily for cycling the leg in and out of the water. These high speed cylinders have a stroke about 8 inches or more.
You see the stainless hydraulic hoses? Behind the hoses hidden in the casing there are two more cylinders which are sometimes called "trim rams" They are a pair of cylinders having a stroke of around 2-1/2 inches. Trim ram control the leg's arc, cycling about 4 inches, thus to control the level of the boat in the water while at speeds higher than trolling. These cylinders have no rod end or heim joint, only blunt rod ends that push against the leg.
When lifting the leg complete out of water, the rams push the leg up slowly then when they extend fully, a valve shuttles to make the tilt cyls take over lifting the leg complete out of water.
Leg is nick for "lower unit"