Eight Key Points for Installation and Commissioning of Hydraulic Rotary Actuators: Hard-won Experience of Senior Engineers

Release time:

2026-07-03 15:21

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Hydraulic rotary actuators are precision hydraulic components. Standardized installation and commissioning can multiply their service life. As a rule of thumb: one more hour spent on precise installation saves a whole year of operational troubles. If you encounter any problems with the installation or troubleshooting of hydraulic rotary actuators, feel free to contact us for professional on-site guidance and product technical support.

“Why do the same hydraulic rotary actuators run for five years without maintenance in neighboring factories, while ours leak oil in just half a year?” The answer usually lies not in the product itself, but in installation and commissioning. According to after-sales statistics from multiple hydraulic rotary actuator manufacturers, more than 60% of early failures — including oil leakage, insufficient output force and crawling motion — stem from improper installation. This article summarizes practical experience from front-line engineers to help you avoid the most common operational pitfalls.

I. Selection of Installation Methods: Four Types; Wrong Selection May Disable the Actuator

There are four mainstream installation methods for hydraulic rotary actuators. Incorrect selection will cause additional bending moments and eccentric wear of components.

1. Foot-mounted Installation (Most Commonly Used)

The actuator body is fixed to the frame via foot bolts.
Application scenarios: Heavy-duty equipment and high-precision positioning occasions.
Key requirements: The base must have sufficient rigidity. Otherwise, the actuator body will tilt under pressure, resulting in piston rod bending.

2. Flange-mounted Installation

The output flange is bolted to the load, and the shell rotates together with the load.
Application scenarios: Equipment requiring frequent reversal of swinging direction.
Key requirements: Tighten flange bolts evenly in diagonal sequence to prevent flange deformation.

3. Straddle Installation (Recommended for Heavy Loads)

The load is supported at both ends; one end is connected to the torque flange, and the other end is mounted on a 180° base.
Application scenarios: Heavy-load and long cantilever working conditions.
Key requirements: The two end bearing seats must be strictly coaxial.

4. Cantilever Installation (Use with Caution)

The load is supported only by the output shaft at a single end.
Strictly prohibited for safety-related scenarios such as aerial work platforms! The bending moment of the cantilever will exponentially accelerate seal wear.

II. Centering and Leveling: The Most Neglected yet Most Critical Procedure

Coaxiality determines the service life of hydraulic rotary actuators.
Inspection Items
Specific Requirements
Consequences of Neglecting Inspection
Model Parameters
Verify that torque, swing angle and working pressure match design requirements.
Undersized parameters cause overload damage; oversized parameters lead to cost waste.
Appearance
Check for collision deformation or damage during transportation.
Damaged sealing surfaces cause immediate oil leakage after installation.
Port Cleanliness
Confirm the integrity of dust plugs on oil ports.
Incoming impurities cause scratches on the spiral pair.
Hydraulic Oil
Oil cleanliness shall meet NAS 9 grade or above.
80% of hydraulic failures are caused by oil contamination.
Fasteners
Ensure bolt grade and specification match mounting holes.
Loose fasteners lead to impact loads.
The axis of the hydraulic rotary actuator must be completely consistent with the rotation axis of the load. Forced eccentric installation will cause the following problems:
The piston rod bears extra bending moment → unilateral wear of seals → oil leakage.
Uneven stress on the spiral pair → local excessive wear → insufficient operating power.
Severe cases: bending and fracture of the piston rod.
Acceptance standard: After installation, manually rotate the output shaft, which shall operate flexibly without jamming.

Base Rigidity

Insufficient base rigidity will amplify deformation under pressurization. Judgment standard: Under full-pressure operation, the displacement of the actuator root measured by a dial indicator shall not exceed 0.05mm.

III. Hydraulic Pipeline Connection: Details Determine Operational Reliability

Stress-free piping: The connected pipelines shall not impose additional tension or thrust on oil ports.
Oil port verification: Carefully check the marks of Port A and Port B; reversed connection will lead to opposite swinging direction.
Bi-directional balance valve: If the system is equipped with a balance valve, strictly verify its installation direction. The balance valve maintains load position and prevents accidental rotation.
Hose length: Reserve a sufficient bending radius to avoid hose tension and pulling on oil ports during swinging movement.

IV. First Step of Commissioning: Air Venting

Importance of Air Venting

Air trapped in the hydraulic system will cause the following faults:
Crawling and jittering movement caused by cyclic compression and expansion of air bubbles.
Cavitation damage to sealing surfaces and spiral pairs.
Loss of positioning accuracy.

Standard Air Venting Method

With no load, unscrew the vent bolt (if equipped). Supply oil slowly under low pressure (<3MPa) and drive the hydraulic rotary actuator to swing at full angle. Tighten the vent bolt once no bubbles are observed in the outflow oil. Repeat the process 2 to 3 times to completely exhaust trapped air.

V. Initial Operation: Slow Operation Ensures Efficient Commissioning

Do not operate the actuator at full pressure and full speed directly after startup!
Standard operation procedure: Fully close the throttle valve → supply oil at low pressure → gradually open the throttle valve by approximately one turn → perform 2-3 low-speed swing cycles → check for abnormal noise, oil leakage and crawling movement → gradually adjust to rated working pressure and speed.

VI. Swing Angle Adjustment

Priority to symmetrical adjustment: Adopt symmetrical angle settings based on the actuator’s central symmetry axis to ensure consistent left and right swinging motion.
Limit screw control: Do not loosen limit screws beyond the adjustment range, otherwise the screws may fall off and cause mechanical collision accidents.
Terminal buffering adjustment: Buffer valves are generally uncalibrated upon factory delivery and shall be adjusted according to actual load inertia. Note: The buffer needle valve is strictly prohibited from full closure, which will cause permanent seal damage.

VII. Commissioning Inspection Checklist

Rank
Wrong Operation
Consequence
Correct Practice
1
Installation without centering calibration
Eccentric wear → oil leakage → scrapped actuator
Strictly calibrate coaxiality
2
Installation on insufficiently rigid base
Pressurized deformation → piston rod bending
Reinforce the base or install supporting brackets
3
Operation without air venting
Crawling movement and cavitation damage
Fully exhaust air in accordance with standard procedures
4
Operation with contaminated hydraulic oil
Spiral pair scratches → internal leakage
Adopt hydraulic oil with cleanliness above NAS 9 grade
5
Inadequate bolt torque tightening
Loose fasteners → impact load
Tighten bolts with a torque wrench per standard torque values
6
Long cantilever without auxiliary support
Excessive bending moment → seal eccentric wear
Install intermediate supports or brackets
7
Overpressure operation
Seal burst → instantaneous failure
Install overflow valve for pressure limiting
8
Rigid pipeline connection without hose transition
Vibration transmission → joint fatigue fracture
Adopt hose connection for vibration buffering
9
Full closure of buffer valve
Terminal impact → seal damage
Adjust buffering parameters according to load conditions
10
No protection against welding spatter
Seal ring burnout → immediate oil leakage
Remove the actuator or implement full shielding before welding
Complete the following item-by-item verification after installation and commissioning:
[1] Full-angle swinging without jamming and abnormal noise
[2] No oil seepage on all sealing surfaces and joints
[3] Uniform swinging speed without crawling
[4] Stable terminal buffering without impact noise
[5] Normal oil temperature (no overheating) after 5 minutes of operation
[6] No position drift after 5 minutes of static holding
[7] All fastening bolts remain tight

VIII. Recommended Maintenance Cycle

Cycle
Inspection Items
Daily
Visual inspection (oil leakage, abnormal operating noise)
Weekly
Fastener tightness inspection and oil level check
Monthly
Oil quality inspection (color, viscosity, impurity content)
Quarterly
Comprehensive seal condition inspection and swing angle calibration
Annual
Complete disassembly and inspection (seal replacement and spiral pair wear measurement)

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