Hydraulic System Maintenance. How to Succeed?

Hydraulic systems have many benefits, but leaks and plenty of maintenance requirements stop many businesses from using them for their applications. Luckily, proper hydraulic maintenance can prevent most of your problems, including leaks, as well as maximize hydraulic system uptime. After all, hydraulic maintenance requirements are not that complicated if you have a detailed preventive maintenance program on hand. In this article, learn about hydraulic fluid maintenance, preventive maintenance task lists, and how to measure the success of your hydraulic maintenance program.

Most Important Questions to Ask Yourself Before You Start

Now before we dive in any further into the hydraulic maintenance best practices, start from asking yourself a few simple questions:

  1. What is my hydraulic system workload?
  2. Is my hydraulic system operating at maximum flow and pressure higher than 70%?
  3. What are the system operating conditions? Is my equipment located in a relatively hot and dirty environment?
  4. What are the equipment manufacturers’ requirements when it comes to preventive maintenance for each piece of hydraulic equipment?
  5. What are the requirements of hydraulic system components’ manufacturers when it comes to hydraulic fluid contamination and ISO particulate?
  6. What are the requirements of filter manufacturers?
  7. Is the previous maintenance history available? If yes, what is the history?

Three Types of Hydraulic Maintenance Explained

There are three main types of hydraulic maintenance: reactive maintenance (RM), preventive maintenance (PM) and predictive maintenance (PdM).

Reactive maintenance stands for breakdown maintenance and involves the repairs that are done to fix the equipment that is already broken.

Preventive maintenance is regular maintenance that is performed on the equipment to prevent it from breaking down. Preventive Maintenance is implemented through a Preventive Maintenance Program.

Predictive Maintenance or condition-based maintenance uses sensor devices to collect information about the system and components and prompts the personnel to perform maintenance at the exact moment when it’s needed. Due to high costs and technical requirements, it is still new to the market and not used very often.

Maintenance Cost Evaluation
Reactive maintenance has the highest repair cost and preventive maintenance has the lowest overall cost (where the two lines meet) Source: https://assetinsights.net/Concepts/Maintenance_Mix_Cost_Evaluation.JPG

Preventive Maintenance Program

The Preventive Maintenance Program is defined by the operating conditions and manufacturer requirements for each individual component and for the system as a whole. To start, you should write down or update the procedures for each preventive maintenance tasks. We recommend having a written copy of the Preventive Maintenance Program even if you own a small business and do not have a maintenance technician on staff. It is vital that all maintenance employees know, understand, and follow the maintenance procedures explicitly created for your business.

Hydraulic Fluid Maintenance Best Practices

Since the hydraulic system uses hydraulic fluid to power hydraulic machinery, you should pay extra attention to hydraulic fluid maintenance and care. Hydraulic fluid performs many functions, including minimizing wear and tear, reducing friction, removing heat, protecting the system from rust and deposits, removing debris, and dirt from the system.

The most common problems that cause hydraulic fluid going bad are system overheating, system contamination, and dirty operating environment. Therefore, to take care of the hydraulic fluid, you should take the following actions:

  1. Prevent the hydraulic system from overheating.Hydraulic fluid gets hot while being pushed through the pumps, tubing, and relief valves. If the system’s temperature is too low, the condensation starts in the reservoir, which can cause pump cavitation. On the contrary, if the temperature is too high, oxidation that causes varnish and sludge deposits occurs. Most hydraulic systems run in the 110-150°F range with mobile hydraulic systems running up to 250°F. If you use a water-based hydraulic fluid, don’t let the temperature go below 140°F, so the water does not evaporate from the fluid. Perform regular checks of the oil cooler and outside the reservoir to prevent overheating.
  2. Keep the System Clean. Prevent contamination of the system by dirt, water, metal debris from entering the system by keeping the reservoir cover, drain lines, and breather fill openings always clean.
  3. Keep the Fluid Clean. Test oil regularly for contaminants. Store hydraulic fluid in the designated containers in the clean environment, clean the fill cap before adding hydraulic fluid. Change and check fluid filters on a regular basis. Filter oil added to the system through portable filters to achieve better results.

Hydraulic Preventive Maintenance Task List

As a general recommendation technician or equipment operator shall perform a weekly scan of the equipment to make sure it’s functioning properly.

The typical weekly Preventive Maintenance list should include, but is not limited to the following tasks:

  1. Check hydraulic fluid levels. Add hydraulic fluid of the same brand and viscosity grade if needed using portable filters when applicable.
  2. Check breather caps, filters, and fill screens.
  3. Check return/pressure/hydraulic filter indicators and pressure gauges for readings.
  4. Sample hydraulic fluid for color, visible signs of contamination, and odor.
  5. Check system temperature using a built-in or spot infrared thermometer. If the temperature is higher than recommended by the manufacturer, check the condition of the cooler and relief valve settings.
  6. Inspect inside of the hydraulic reservoir for any signs of aeration. Use a flashlight and look into the fill hose for any signs of foaming or small whirlpools. Aeration may be a sign of a leak in the suction line or faulty shaft seals, so it’s important to inspect the reservoir on a regular basis.
  7. Inspect hydraulic hoses, tubing, and fittings for leaks and frays. Remember that any leakage is an environmental and safety hazard since hydraulic fluid gets hot inside the system and is highly toxic. If the fluid level gets too low, the system will operate at reduced capacity and will get overheated.
  8. Inspect proportional/servo valves for overheating. High temperature means that the valve is sticking.
  9. Listen to the pump for making any unusual noise. The noise may be a sign of cavitation. Cavitation is the formation of bubbles or so-called cavities in the hydraulic fluid and is caused by the air that gathers in the areas of relatively low pressure around an impeller. It damages the pump, decreases the flow, and causes vibration if not treated. 
  10. Scan the electric drive motor with a handheld infrared thermometer for hot spots.

Tracking Success Made Easy

To measure the success of a hydraulic maintenance program, you need to watch for the three key metrics:

  • track downtime if any
  • calculate costs associated with the downtime
  • test the hydraulic fluid

Let’s focus on each of them individually. You’ve done everything in our list of preventive maintenance tasks, but the equipment still broke down. Now that it happened learn how to measure the effects of the downtime on your business.

First, identify which of the components of the hydraulic system has failed. Then try to determine what caused the failure. It can be anything from wear and tear associated with time to the low quality of the components. Finally, make sure the part was replaced or repaired and discuss with the team if the failure could have been prevented.

After fixing the system, it’s time to calculate costs associated with the downtime. To do that, add the costs associated with the part replacement or repair, labor, and money lost while not using the equipment.

As the last step, analyze hydraulic fluid for contaminants, including metals and water. Fluid analysis is one of the most important diagnostic tools and gives you information on filter performance as well as internal leakages and wear debris. Luckily, in 80% of the time, hydraulic failures can be prevented by analyzing the fluid.

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