What characterizes a hydraulic system?

A hydraulic system is characterized by its use of liquid fluids, typically hydraulic oil or water, to transmit power. The defining feature of hydraulic systems is their ability to transmit force through incompressible fluids, allowing for the generation and control of high force and movement. This is achieved by applying pressure to the fluid in a confined space, which can then be directed to perform work, such as lifting heavy loads or operating machinery.

The notion of high force capability is a crucial attribute of hydraulic systems. They can amplify force more effectively than mechanical systems or systems that rely on gases, making them suitable for applications where significant power and precise control are required, such as in construction equipment, automotive brakes, and aerospace applications.

The other options do not accurately describe the characteristics of hydraulic systems. Using gases for power transmission pertains to pneumatic systems instead. Solid mechanisms typically relate to mechanical systems, which are distinct from hydraulics. Operating at low pressures only contradicts the nature of hydraulic systems, which often operate at both low and high pressures depending on the application. Thus, the use of liquid fluids and high force capability is what fundamentally defines a hydraulic system.