A hydraulic system consists of a motor, valves, pump, sump, hydraulic fluid, and actuators. This combination can be configured into numerous applications to reduce mechanical complexity and enhance power transfer. Hydraulic power systems are highly reliable if properly maintained, failure to which could result in expensive repairs.
Even the most resilient and strongest hydraulic systems fail every now and then and there can be hundreds of reasons behind it. Proactive hydraulic system maintenance requires the detection and correction of problematic conditions that would cause equipment failure. Telltale signs of hydraulic problems include high fluid temperature, abnormal noise, and reduced machine operation.
High fluid temperature above 82°C or 180°F can accelerate degradation of the hydraulic fluid and damage seals. High fluid temperature occurs when viscosity falls below the most favorable value for the components. Fluid temperature above 180°F can be caused by any factor that increases the system’s heat load or leads to the reduction of the system’s capacity to dissipate heat through the reservoir.
Therefore, the fluid level in the reservoir should be closely monitored while ensuring that it stays at the correct level. It’s also important to check that there is no debris or buildup of dirt that could obstruct airflow around the reservoir. The heat exchanger should be inspected to ensure there is no blockage in the core. In addition, the performance of cooling circuit components should be closely monitored and replacements should be done as necessary.
Heat is generated when fluid moves to an area of low pressure without any ongoing applications. When this happens, any part with abnormal internal leakage will cause increased heat load. For instance, this could be a wrongly adjusted relief valve or a cylinder releasing fluid beyond the piston seal. Correcting this requires the maintenance team to identify and replace the heat-generating component.
Conversely, heat is generated when air is compressed. It is, therefore, important to inspect the system for causes of cavitation and aeration. Inadequate lubrication can damage components due to excessive thinning of the oil film, especially when fluid temperatures are high. To prevent this damage, system components should be adequately lubricated and a fluid alarm installed in the system.
Cavitation and aeration are the two major causes of abnormal noise in hydraulic systems. Aeration is caused by hydraulic fluid contamination, which results in an alarming knocking or banging noise when air compresses or decompresses. Other symptoms include erratic actuator movement and foaming of the fluid.
Aeration causes damage to the system components through overheating, loss of lubrication, and burning of seals. Since air typically enters through the pump’s inlet, it’s important to ensure clamps and fitting are tight and that intake lines are in good condition. Old or suspect pump intake lines should be replaced.
Cavitation occurs when the demand for fluid by any part of a hydraulic circuit is higher than the supply. This results in reduced absolute pressure in that part of the circuit, forming vapor cavities that produce a knocking noise when compressed. Cavitation causes metal erosion, which contaminates the fluid, damages hydraulic components, and even causes mechanic failure. Cavitation usually occurs at the pump when the fluid vaporizes as a result of a restricted intake line or clogged inlet strainer. It’s crucial to make sure that the inlet filter or strainer does not become clogged. Old or suspect intake lines should be also replaced to prevent collapse.
A reduction in machine operation typically manifests itself in slow operation or longer cycle times. Loss of speed may also indicate loss of flow either through internal or external leakage. Pressure drops and heat is generated when there’s an internal leakage. Components with abnormal internal leakage can be detected using an infrared thermometer. However, measuring temperature is not always definite and as such, there may be need to use a hydraulic flow-tester.
Proactively monitoring cycle time, fluid temperature, and noise is an effective way to troubleshoot common problems that can lead to expensive component failure, repairs, and unexpected downtime of hydraulic equipment.
Equipping your employees with knowledge in troubleshooting techniques that will help ensure high reliability and prolonged lifespan of your hydraulic power systems requires formal training.
For this reason, it’s important to enroll them in a program through which they can acquire the skills needed to accurately and efficiently diagnose and correct problems and malfunctions related to hydraulic systems. Formal training provides students with theoretical knowledge on numerous topics as well as practical laboratory exercises. Investing in employee training will help your business run faster and with fewer incidents.
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