Hydraulic machinery uses fluid power to perform work. It operates by transmitting force through a liquid, typically oil or water, which allows machines to lift heavy loads or move components with ease. Common examples include excavators, forklifts, and hydraulic presses. The basic principle behind hydraulic machinery is Pascal's Law, which states that pressure applied to a confined fluid is transmitted equally in all directions. This enables hydraulic systems to amplify force, making them efficient for various applications in construction, manufacturing, and automotive industries.