By Dovydas Kersys · Chapter 39 of 58 in Machine Commissioning.
Before you begin: Follow the machine documentation, risk assessment, site procedures and lockout/tagout requirements. Commissioning can expose personnel to electrical energy, stored pressure and unexpected motion. Never defeat a safety function merely to make a test easier. Examples and diagrams are generic and must be checked against the actual machine.
Hydraulic commissioning requires cleanliness, correct fluid level, pump rotation, pressure control, air removal, filtration and controlled actuator movement. Never assume a new hydraulic system is clean or correctly primed.
Hydraulic startup should progress from clean supply and safe pressure toward controlled loaded motion.
Why this matters during commissioning
Incorrect pump rotation or running dry can damage a hydraulic power unit quickly.
Commissioning procedure
- Verify fluid type, level and reservoir cleanliness.
- Confirm pump coupling and expected rotation before loaded operation.
- Prime/bleed according to system design.
- Start at low pressure/unloaded condition where practical.
- Check leaks, abnormal noise, filter indicators and temperature.
- Prove relief/pressure control settings and then actuator direction at controlled speed.
Common failure patterns
- Pump starts backwards.
- Suction valve closed.
- Relief valve set high before system is proven.
- Air trapped in cylinders causes jerky motion.
Evidence to record
- Measured value and test point
- Expected value / expected state
- Observed value / observed state
- Pass/fail result and any deviation
- Name/date or responsible person where required
FIELD RULE: Noise, heat and foamy oil during first startup are diagnostic signals, not conditions to ignore until later.
Continue the series
- Previous chapter: Pneumatic Commissioning
- Next chapter: Temperature and Pressure Instrumentation: Commissioning Guide
- Browse all Machine Commissioning chapters
Adapted from Machine Commissioning for Maintenance and Automation Technicians, by Dovydas Kersys. © 2026 Dovydas Kersys. Featured cover image is an AI-generated editorial illustration.