Glossary · Pneumatics and hydraulics
Hydraulics
Also known as: Hydraulic power, Oil hydraulics
German: Hydraulik
In engineering, hydraulics is the technology of transmitting and controlling power by means of a pressurized liquid, typically oil. ISO 4413 specifies general rules and safety requirements for hydraulic systems and their components in machinery.
- Fluid power
- Standards
In one sentence
Hydraulics transmits and controls power with pressurized liquid; ISO 4413 sets safety rules for hydraulic systems on machines.
Example
Injection molding machines use hydraulics for the clamping unit because it produces very high forces compactly.
How it applies
- Engineering: Hydraulic systems provide high forces and power density. ISO 4413 covers design aspects such as pressure limitation, load holding and energy release; conforming to it doesn't by itself make a machine safe.
- Commissioning: Flushing, filling, bleeding and pressure setting follow a defined procedure.
- Maintenance: Accumulators, trapped pressure and raised loads are typical hazards; energy must be released before work.
- Documentation: Provide hydraulic circuit diagrams with symbols according to ISO 1219-1, set values, fluid data and maintenance intervals. Describe depressurization, including accumulators, as part of the Energy isolation and Lockout/tagout (LOTO) procedures.
Hydraulics vs. pneumatics
Hydraulics uses liquid and works at high pressure with stiff, strong motion. Pneumatics uses air at low pressure, is fast and clean, but less stiff.