Hydraulic cylinders are a common part in a variety of machines from excavators to bulldozers to cranes, trucks, and more. While the engine, the transmission, and the tires and tracks are designed to move the machine itself, the hydraulic cylinders are designed to move their individual parts. When a boom extends, a blade lifts, or a bucket tilts that motion was likely controlled by a hydraulic cylinder.
At their most basic, hydraulic cylinders convert pressure into movement and for the most part they’re designed to do one of two things -- push or pull. If you look around a heavy construction equipment machine, you’ll find cylinders positioned all over it. If a component needs to extend or contract, it’s a good bet there's a cylinder making it happen.
Cylinders are expert extenders, but when working in heavy construction equipment they also have to be hearty enough to not just lift the huge components -- they have to be able to lift the part with an extra heavy load added on top. The end result? Big machines need big cylinders
Hydraulic cylinders come in two types: single acting and double acting. In a single acting cylinder only one chamber exists in the cylinder to hold the hydraulic fluid (or to push) and the countering force is an external mechanism like gravity. In a double acting cylinder, oil pressure is applied to a piston in two directions through two separate chambers.