NCCER Millwright Practice Exam 2025 - Free Millwright Practice Questions and Study Guide

A hydraulic system is designed to use liquid pressure to transfer power and perform work. In these systems, a fluid, typically oil or water, is contained within a closed system of pipes and actuators. When pressure is applied to the fluid in one part of the system, it can be transmitted throughout the system, enabling movement and operation of machinery or mechanical components. This principle relies on the incompressibility of liquids, allowing for efficient and effective transmission of force.

For example, in a hydraulic lift, fluid is forced into a cylinder, which raises the platform while lifting heavy loads. The ability to control and amplify force through hydraulic pressure makes these systems crucial in various applications, including construction, automotive, and manufacturing.

The other systems mentioned operate differently: pneumatic systems primarily use air and compressible gases, vacuum systems work with pressure differentials in a gas-filled environment, and mechanical systems rely on physical components like gears and levers to transmit force and motion without necessarily involving liquid pressure.