Hydraulic systems are commonly used in industrial and mobile systems and consist of power packs, control valves, actuators, fluids, and other essential and optional components. These systems can fail due to reasons like fluid contamination, insufficient fluid, use of the wrong fluid, leakage, loose connections, excessive heat or pressure, and cavitation. So, the importance of proper maintenance can’t be overstated. This article is for educational purposes, and the specific maintenance required depends on the type of system and local conditions.
Maintenance covers many routine and troubleshooting activities to keep systems in satisfactory working condition. These activities fall into two main categories: preventive maintenance, which aims to forestall issues, and corrective maintenance, which addresses existing problems. Typical maintenance activities include visual inspections, servicing, examinations, and overhauls. It is crucial to safeguard exposed parts, clean components during assembly, apply the appropriate torque while fitting components, and flush the assembled system.
Maintenance technicians play a crucial role in maintaining hydraulic systems. Their deep understanding of physical laws, functions, and symbols, coupled with strong maintenance and troubleshooting skills, is paramount. They should also take adequate safeguards. It is important for each technician to know the machine, follow best maintenance practices, use the instruction manual, compile and follow a maintenance checklist, and stock essential spares. This emphasis on their knowledge, skills, and safety consciousness will make them feel competent and committed.
Before commencing maintenance, technicians must adhere to a series of safety procedures. These include obtaining work authorization, wearing personal protective equipment (PPE), turning off the electrical supply, shutting down the hydraulic supply, and releasing any trapped pressure. By following tagout and lockout procedures, securing the work area, providing good ventilation, and securing machine parts, technicians not only ensure their own safety but also that of others, fostering a sense of security and protection. During maintenance, technicians should take safety precautions and use appropriate tools. Any part replacements must adhere to the original specifications.
Next, we will examine the practices involved in maintenance at the component level. The primary consideration is the fluid component. A proficient maintenance technician should have knowledge of fluid properties and behavior, general fluid maintenance and monitoring activities, fluid handling precautions, and proactive maintenance measures like filtration, fluid sampling, and fluid analysis. General fluid maintenance activities include cleaning and checking appearance and smell. Furthermore, the technician should monitor fluid levels, temperature, and potential leakages. Additionally, the technician must assess signs of wear, inappropriate tensioning of V-belts, noise, vibration, cavitation, under-lubrication, improper foundation, and misalignments. Regular monitoring of particulate levels, viscosity, water content, oxidation, and acid levels is essential, along with the timely replacement of fluids. The filters require regular maintenance, including checking clogging indicators and replacing filter elements and worn-out components.
A power pack comprises essential components such as a tank, pump-motor unit, and PRV. Potential pump failures arise from wear, internal surface degradation, leakage, insufficient fluid delivery, noisy operation, drive failure, or pump breakdown. Preventive maintenance activities for power packs involve maintaining fluid and filters, adjusting pressure levels and flow rates, and managing heat, turbulence, vibration, and noise.
Hydraulic valve repair involves disassembling the valve, inspecting the plunger, body, spring, O-rings, and coil connections, replacing damaged parts, reassembling the valve, and conducting tests.
When maintaining hydraulic cylinders, it is important to carefully inspect the pistons and piston rods for wear, dents, damages, nicks, scoring, and pitting. Other maintenance tasks include checking the cylinders’ roundness and straightness, inspecting for internal and external fluid leakages, replacing gaskets, replacing leaking piston and piston-rod seals, aligning cylinder and mating parts, checking mountings for tightness and cracks, inspecting for sluggish operation and creeping, and opening bleed ports as necessary.
Maintenance of a system with accumulators involves the following steps: attaching warning signs, providing a safety block, depressurizing and isolating the accumulators before servicing, pre-charging and maintaining the pre-charge pressure, maintaining maximum working pressure and operating temperature within limits, and adjusting the accumulator charging and discharging rates.
Maintenance of fluid conductors, fittings, and support includes regularly inspecting them for defects, damages, scratches, kinks, and burrs, checking for leakages, replacing defective ones, examining for loose connections, and tightening loose connections.
This article summarised hydraulic maintenance. Maintenance technicians must be familiar with many maintenance tasks related to hydraulic systems. Continuous knowledge updating and skill development will help them remain competent.
By
Joji Parambath
Resource Person and Author
References:
1. Industrial Hydraulic Systems and Circuits -Basic Level (In the SI Units)
2. Industrial Hydraulics -Basic Level (In the English Units)
3. Maintenance, Troubleshooting, and Safety in Hydraulic Systems
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About the Author
Joji Parambath is an accomplished expert in Pneumatics, Hydraulics, and PLC with an extensive 25-year background in the field. Over the course of his career, he has trained many professionals from diverse industries, faculty members, and engineering students.
Joji is the primary faculty member at Fluidsys Training Centre in Bangalore, India, which offers comprehensive training in Pneumatics and Hydraulics. He has authored an impressive 39 books on the subject, all designed to convey knowledge in a simplistic and easy-to-understand manner.
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