A hydraulic cylinder is a device which converts fluid power into linear mechanical force and motion proportional to the effective cross-sectional area of the piston. Their output force, or motion, is in a straight line. Their work applications may include pushing, pulling, tilting, and pressing. Cylinder type and design are based on specific applications. Cylinders usually consist of a movable element such as a piston and piston rod, plunger or ram, operating within a cylindrical bore. Common types of cylinders include double-acting, single-acting, and telescoping.