Importance of Keeping Hydraulic Oil Clean and Filtering of Contaminants in a TBM System
Downtime on the jobsite is sometimes unavoidable. Most of us mere mortals cannot control things such as the weather or power outages, so it is important to be proactive in the things we can control. Preventative maintenance, awareness and proper operation can not only save you costly hours of downtime and parts but can also save your team many hours of frustration and anxiety.
Keeping the hydraulic oil clean and free of contaminants in your TBM system is imperative to keep your system and project running smoothly. There are four main types of contaminants that can be detrimental to your system. These are water, particulates, varnish and sludge. Water is the most common contaminant in hydraulic oil. It can enter the system through leaks, condensation, or improper maintenance. Water can cause corrosion, foaming, and degradation of the oil. Particulates are solid particles that can come from a variety of sources, including wear debris, sealant material, and contamination from the environment. Particulates can cause system problems such as clogged filters and valves, increased wear, and decreased efficiency. Varnish is a type of contaminant that forms when lubricating oils degrade. It can cause buildup on surfaces that clog filters and other components. Varnish leads to increased wear and decreased efficiency. Sludge is a type of contaminant that forms when lubricating oils degrade. It is a thick, sticky substance that can clog filters and other components within the system. Sludge can also lead to increased wear and decreased efficiency.
It is also important to use the correct hydraulic oil designed for your system and environment. Using a non-compatible hydraulic oil will compromise the additive performance, cause corrosion, and lead to increased mechanical wear.
While Akkerman equipment has in-line filters strategically designed within the hydraulic system to trap particulates, varnish and sludge from the hydraulic oil to safeguard against wear and premature failure, it is always important monitor the condition of the filters when the system is operating. Under normal operating conditions, the filter indicator gauge should indicate “green” as shown in Figure below.
Over time the hydraulic filter will trap contaminants within the hydraulic system requiring additional backpressure to pass oil through the fine-mesh screens resulting in the gauge to climb towards the “yellow” and eventually “red” indicator levels. If the indicator reaches the “red” zone, the filter is essentially plugged and will enter bypass mode allowing hydraulic oil to freely pass through the housing without being filtered. Under normal operating conditions, running the hydraulic system with indicators in the “red” may directly introduce contaminants into the reservoir.
The filter bypass is also a system safety function for basic startup operations. When equipment is first started up and the hydraulic oil is cold and highly viscous, it may be common to see filter indicators read higher than anticipated or even within the “red” zone until the oil is up to operating temperature. The internal bypass safeguards against excessive pressure spikes that can cause a filter to burst upon startup conditions during these scenarios.
Water is one contaminant that will freely pass through filters. If your hydraulic oil begins to appear cloudy, you likely have an issue with water in your hydraulic fluid. It is likely that you will require a fluid change at this point. If your equipment is in for routine maintenance, it is recommended to send in some of your fluids to an approved laboratory for analysis to determine if they need to be completely changed.
Since water is denser than oil, water will settle to the bottom of the hydraulic tank over time and can be periodically drained by removing the plug on the bottom of the tank. Although this method will not rid all water contaminants from the system, it can be an effective preventative maintenance strategy.
Tunneling is a job performed in a dirty environment. Most contaminants enter your hydraulic system when you make and break connections during a pipe change. Each time this is done, you open a closed-loop system for debris. No matter how competent your crew, contamination will enter the system when adding feed and return lines, swapping components, or storing equipment in the elements over time. The filters are designed to trap these contaminants, but there are some useful takeaways that will prolong the life of your equipment.
Important Strategies to Prolong Hydraulic System Life:
Ensure that hydraulic oil has warmed up to operating temperature BEFORE making new tunnel connections.
Properly store your hydraulic lines with appropriate caps and plugs.
Change hydraulic filters BEFORE they are blocked by contaminants. Monitor operating pressure and note incremental changes on the indicator gauge.
Keep hydraulic fluid level at optimum level. Check prior to startup and monitor routinely.
Always inspect any tunnel connections for contaminants prior to installation.
Always keep spare filters with the approved micron rating for your system.
Add periodic fluid testing to your preventative maintenance strategy if you haven’t done so already.
Use hydraulic oil compatible with OEM guidelines and environmental conditions.
Monitor and note any changes to a hydraulic system’s sound or vibration.
Inspect and clean hydraulic tank breather periodically. The breather allows air to enter/exit the tank as fluid level changes.
Akkerman customers can access digital copies of their Operator’s Manual at anytime by visiting https://www.akkerman.com/literature-and-manuals/ for further information. To speak to one of our Aftermarket Support Specialist in person, please contact us at (800) 533-0386.
