Air in a hydraulic system significantly hinders performance because it's compressible, unlike hydraulic fluid, which is virtually incompressible.
Here's a breakdown of the adverse effects:
- Reduced Efficiency: Air's compressibility absorbs energy that should be transmitted to the hydraulic components. This leads to sluggish operation, reduced power output, and overall inefficiency.
- Spongy Response: The presence of air creates a "spongy" feel in the system. When the operator actuates a control, the initial motion compresses the air instead of immediately actuating the intended device. This delay and lack of precision can be problematic, especially in applications requiring fine control.
- Erratic Operation: Air bubbles can cause erratic and unpredictable movements. As pressure fluctuates, air compresses and expands, leading to jerky motions and inconsistent performance of hydraulic cylinders and motors.
- Increased Wear and Tear: The compressibility of air can lead to cavitation. Cavitation occurs when air bubbles collapse violently due to pressure changes, generating shock waves that erode hydraulic components like pumps, valves, and cylinder walls. This reduces the lifespan of these parts.
- Overheating: The compression and expansion of air generate heat, which can lead to overheating of the hydraulic fluid. Excessive heat can damage seals, reduce fluid viscosity, and accelerate fluid degradation.
- Contamination: Air can introduce moisture into the system, which can lead to corrosion and rust formation. Air can also carry other contaminants, further degrading the hydraulic fluid and damaging components.
- Difficulty in Achieving Precise Control: Accurate positioning and controlled movements become challenging with air in the system, particularly in applications such as robotics, precision machining, and automated assembly.
Preventing Air in Hydraulic Systems:
- Proper Bleeding: Regularly bleed the system to remove trapped air. Many hydraulic systems have bleed screws or valves located at strategic points to facilitate this process.
- Proper Filling: When filling or refilling the hydraulic system, ensure the fluid level is correct and that air isn't introduced during the process.
- Seal Integrity: Maintain good seals to prevent air from entering the system through leaks. Regularly inspect and replace worn or damaged seals.
- Reservoir Design: A well-designed reservoir will allow air to separate from the fluid before being drawn back into the system.
- Maintain Fluid Level: Keep the fluid level above the pump intake to prevent air from entering the system during operation.
In summary, air compromises the fundamental principle of hydraulics – incompressibility – leading to a cascade of problems that degrade performance, reduce component life, and increase maintenance costs. Proper maintenance and operating procedures are crucial for keeping hydraulic systems free from air.
