Hydraulic fluid is to an excavator what blood is to people. It not just enables various parts to move as they should; it guarantees their effectiveness therefore ensuring long service. This comprehensive guide will walk you through the process of adding hydraulic fluid to your excavator safely and correctly.
Understanding Hydraulic Fluid
Hydraulic fluid transfers power within the system of hydraulic components, lubricates them, and dissipates heat. It plays a crucial role in ensuring the hydraulic system's normal operation, efficient performance, and reliability.
Hydraulic oil for excavators consists of mineral oil and other additives, such as organic silicon-based and ethylene glycol-based additives. These additives improve lubrication performance and enhance moisture control.
Key Functions of Hydraulic Fluid
Power Transmission: Hydraulic fluid transmits power from the hydraulic pump (connected to the engine) to hydraulic cylinders, motors, and other components through valves, pipes, hoses, and actuators. This enables the excavator to deliver great force with little mechanical complexity.
Lubrication: Because the hydraulic oil passes through every moving part, it helps to lubricate them and make sure they do not actually rub against each other. By preventing untimely component failure, this lubrication extends the life of your engine and reduces friction between metal parts in hydraulic components like cylinders, reducing wear and tear.
Heat Dissipation: During the operation of the hydraulic system there is a significant generation of heat. This heat is absorbed by the oil, which it carries away from sensitive parts to aid in keeping components of your engine at ideal running temperatures and not allowing them to overheat. The fluid absorbs heat generated within the hydraulic system, maintaining a suitable working temperature range to prevent overheating and adverse effects on system performance and component longevity.
Sealing and Cushioning: It creates seals to prevent leakage, and provides cushioning to control the speed and force of hydraulic cylinder movements smoothly. The fluid forms a seal that enables pressure to build up in the hydraulic system, ensuring smooth operation.
Hydraulic oil operates the excavator's boom, arm, and bucket, facilitating various working actions using hydraulic cylinders connected to the main hydraulic circuit. It also enables 360-degree rotation through the hydraulic swing motor.
Choosing the Right Hydraulic Fluid
ISO 46 Hydraulic Oil Specifications
The vast majority of modern hydraulic excavators use ISO 46 as the hydraulic fluid. ISO 46 hydraulic oil is a medium-viscosity oil commonly used in heavy-duty applications. It is well-suited for machinery that operates in warmer climates or conditions, as its higher viscosity helps it maintain stability and performance at elevated temperatures.
This oil grade is ideal for excavators and loaders as it ensures efficient operation under the strain of lifting and moving materials. The greater viscosity of ISO 46 hydraulic oil also helps reduce internal leaks in older machinery, providing a more consistent performance over time.
ISO 46 suits equipment with operating pressures 1,500-3,000 PSI and moderate-speed pumps. It is a suitable choice for 20-50 ton excavators operating in 40-95°F ambient temperatures, providing optimal pump protection and valve response.
Alternative Options
ISO 32 hydraulic oil is a lower-viscosity oil, making it lighter and easier to flow, particularly in cooler environments. This is an appropriate replacement for ISO 32 that was often used in older plant and agricultural machinery with gear pumps. Consider ISO VG 32 for consistent cold operation below 40°F.
For semi-tropical conditions and continuous high-temperature operation above 95°F, ISO 68 is recommended. Generally 68 is used in semi-tropical conditions.
Critical Importance of Manufacturer Recommendations
Only use the hydraulic fluid for mini excavator specified by your manufacturer for your particular machine. Using an off-brand mini excavator hydraulic oil or improper substitutes is just asking for performance issues and premature hydraulic failures. If you don't use the correct type, viscosity and quality fluid, the components of your excavator can experience a number of problems. For example, it could affect your excavator's efficiency and resistance to wear of components (premature breakdowns). Also, by not using the proper fluids you risk poor lubrication, corrosion, and overheating which also affect the working life of your components.
Signs You Need to Add Hydraulic Fluid
Identifying these signs of hydraulic oil shortage promptly can reduce wear and aging of equipment parts, and improve operational safety. The following are some common signals that will draw your attention:
- Abnormal rise in hydraulic system temperature
- Slower response speed and less agile movements when using an excavator for a project
- Insufficient power for the excavator to complete normal work tasks
- Abnormal noise from the hydraulic system during operation, usually cavitation noise caused by the pump running empty
- Inconsistent hydraulic cylinder movement, such as irregular or intermittent behavior
If you notice these signs, it means there is a shortage of hydraulic oil, and you need to check and refill it promptly.
Safety Precautions Before Starting
Before any checks or fluid additions can be performed, proper safety needs to be ensured. These safety measures are critical to protect you from injury and ensure accurate readings.
Essential Safety Steps
Secure Your Excavator: Make sure your excavator is secured on a firm, flat surface level with the parking brake on. This will ensure you avoid any injuries and ensure a safe and comfortable operation. Check that your excavator is not on a slope of any kind. The parking brake should be engaged, and the vehicle should be situated on plain terrain.
Engine and Temperature Safety: The engine should be switched off and completely cold if it was run previously. You should also take the key out of the ignition. After operating the excavator, the hydraulic oil temperature may reach 60-80°C. If you open the oil level inspection cover or fuel tank cap at this time, the high-temperature oil may splash out due to pressure and burn your hands, face, and other parts of your body. It is recommended to wait for 15-30 minutes after stopping the machine (the specific time can be adjusted according to the ambient temperature) and wait until the oil temperature drops to a safe level (the outer wall of the oil tank should not be hot to the touch) before operating. This cooling phase is important for two reasons: It lets the hydraulic oil sit in the tank and helps get a more accurate reading of the level. It minimizes the potential for burns from hot oil or parts during the check.
Pressure Relief: Less obvious, but also important is ensuring there is no pressure in the tank before you remove the cap. This prevents accidental starting of the equipment.
Personal Protective Equipment: Always wear protective gear - make sure you prepare with safety glasses, gloves, and protective clothing, as hydraulic fluid under pressure may cause injury if it comes in direct contact with skin or eyes. When adding hydraulic fluid, ensure you wear appropriate personal protective equipment, such as goggles and gloves. This will protect you from contamination by hydraulic oil and other potential hazards.
During the inspection, you may come into contact with oil stains or metal parts or be exposed to the risk of oil splashes. Gloves can protect your hands from oil stains and scratches from parts. Safety glasses can prevent oil and dust from splashing into the eyes. They prevent hand sweat, dust, and oil from coming into direct contact with the oil level gauge and filler cap, preventing impurities from entering the fluid. They also provide a non-slip and scratch-resistant surface when opening the oil cap and touching the outside of the tank. It is recommended to give priority to nitrile gloves that are wear-resistant and not easy to absorb oil, rather than cotton gloves that are easy to absorb oil and difficult to clean.
Leak Detection Safety: If there is a suspected leak, do not use your hands to search for the leak along hydraulic hoses or components. Instead, use tools such as mirrors to identify potential leaks and avoid the risk of fluid injection injuries.
Communication: Maintain active communication with those around you while adding hydraulic fluid. This ensures that everyone is aware of the current work status and safety precautions.
Step-by-Step Guide: How to Add Hydraulic Fluid to Excavator
We advise that you refer to the owner's manual always. But generally, the process is almost the same for most models, as follows:
Step 1: Locate the Hydraulic Tank
The hydraulic tank is usually found adjacent to or running along the sides of the chassis, although exact location may vary in some cases. The hydraulic oil tank is usually fixed. Most excavators place it behind the counterweight or on the side of the fuselage for easy refueling and inspection.
It is usually marked with a hydraulic oil symbol. In case you don't know where yours is located, consult your manual on how to add hydraulic fluid to excavator.
Step 2: Position Your Excavator Properly
Park the mini excavator on level ground. It also provides an accurate oil level reading, eliminating false low or high readings. It's recommended to park the excavator on compacted concrete or hard-packed dirt, rather than soft soil, slopes, or potholes.
Fully lower the boom, arm, and bucket. This drains the most amount of hydraulic oil back to the reservoir which will increase your accuracy when checking for proper fluid level in the system. Fully lower all working devices (bucket, boom, and shovel) to the ground. If the boom or bucket is not lowered, it may drop unexpectedly due to residual pressure in the hydraulic system. Moreover, after the working device is completely landed, the hydraulic oil can flow back to the oil tank. Oil retention in the lines may cause the oil level in the tank to be falsely low, affecting the accuracy of the reading.
Step 3: Check Current Hydraulic Fluid Level
After finding the tank, there are two ways to check hydraulic fluid: use the sight gauge or the dipstick. These will help you determine the levels of hydraulic fluid in the tank.
Sight Glass Method: If you have a sight glass on the side of your excavator, all you have to do is look at it to see if the oil level is right. Many hydraulic systems have a sight glass to visually inspect the fluid level. The level should fall within the minimum maximum fill lines.
Dipstick Method: Remove the dipstick and dry it with a clean lint-free rag. After that push in all the way back then pull it out again to check the oil level. It will be between the add and pass line on a dipstick for old oil. The dipstick is most often located near the hydraulic pump or reservoir with the fluid. It will also be labeled with a special symbol or the word 'hydraulic'.
Your goal is to always fill your mini excavator hydraulic fluid until it's between the maximum and minimum lines. In case it falls short of the minimum point, it means you need to top it up.
Step 4: Prepare the Work Area and Clean Around Opening
Clean the area around your oil reservoir cap or dipstick before you open it. This way, contaminants do not enter the system during inspection. Carefully remove the fill cap or any breather components to access the tank. This is an excellent opportunity to give another confirming glance at your oil levels using that sight gauge or dipstick.
Step 5: Inspect Existing Fluid Quality
But before just topping it off, it's crucial to check the condition of the existing hydraulic oil. Does it look discolored, murky, or contain particles of debris? If so, you likely have some contaminated oil issues rather than just low levels.
In addition to monitoring the level, inspect its consistency as well for:
Color: Clean hydraulic oil should be translucent and amber in color. Dark or cloudy oil may indicate contamination or degradation. A dark brown fluid color is acceptable for older machinery. Blackish fluid indicates excessive heat breakdown and may affect performance.
Smell: Hydraulic oil when clean, fresh, and uncontaminated, has a mild characteristic odor. A burnt smell (due to overheating) and a sour-smelling odor (chemical breakdown) are not good signs. A robust burnt smell signals oil breakdown from overheating. Inspect hydraulic components for leaks and overheating.
Contamination: Frothy or milky fluid indicates contaminated fluid with air, moisture, or coolant. Requires fluid flushing and filtering. Check for metal filings in used fluid using a magnet. Indicates internal component wear requiring replacement.
In that case, you'll want to drain and do a full fluid flush instead of risking pushing those contaminants further through the hydraulic circuit.
Step 6: Add the Correct Hydraulic Fluid
Carefully pour your new, correct excavator hydraulic fluid into the tank. Be careful not to overfill past the maximum line. Use a funnel to help avoid any potential spills or messes.
It is essential to maintain optimal fluid levels indicated on the dipstick. Take good care while pouring the oil into the hydraulic oil tank. Removing oil is slightly more complicated, but if you use a turkey baster or a little pump, you can easily extract the excess.
At this stage, it is crucial to use the correct oil type for your engine. Otherwise, you will cause failure or even damage to your excavator. If you're unsure about the type of hydraulic fluid, refer to the excavator's user manual or manufacturer specifications to ensure you use the correct type and specifications.
Step 7: Replace Components Securely
Once the fluid level is correct, securely replace the fill cap or any other components you removed earlier.
Step 8: Start Engine and Check for Leaks
After applying your new fluid, reseal every component and cap you removed or anything that is visible. The next step is to start the engine and let it idle for a few minutes. One must remain alert during this phase!
Carefully inspect all hydraulic hosing, lines, fittings, and components to identify any external leaks. Besides, you do not want your new fluid to leak before it even gets in there to do its thing.
Step 9: Cycle Hydraulic Functions
With the engine still running, briefly cycle through all your excavator's hydraulic functions - boom, arm, bucket, etc. This helps fully circulate that fresh fluid throughout the entire system.
Step 10: Final Level Check After Cooling
After you've completed your cycling, shut off the engine. Your excavator will need 15-30 minutes to cool back down fully before you can take an accurate fluid level reading. Allow 10-15 minutes for settling, and check the level as specified when the fluid is warm.
Once your machine has had sufficient time to cool, make your way back over to the sight gauge or dipstick. Due to the hydraulic components being active during the cycling process, you may notice the fluid level has dropped somewhat. Do not worry- this is normal.
Carefully top up the reservoir by adding additional fluid until you once again reach the proper level between the minimum and maximum markers. After the necessary addition or removal of fluid, make sure that the oil level is appropriate. To do that, insert the dipstick in the hydraulic reservoir once again and ensure the mark is in the correct position. If it is still not right, repeat the previous step.
Common Mistakes to Avoid
Checking on uneven ground: This can lead to false readings.
Overfilling: Too much oil can cause foaming and system damage. Hydraulic fluid will be forced out of the breather pipe or filler neck when tank pressure increases.
Using the wrong type of fluid: Always use the manufacturer-recommended oil.
Neglecting to clean the area: Dirt entering the system can cause significant problems.
Ignoring small leaks: Address any leaks promptly to prevent system failure. It is essential to fix any leaks before going any further.
Checking hot fluid: Hot oil expands, which can lead to overfilling if checked when warm. Checking cold oil gives you a more consistent baseline for comparison over time. The oil is cooler and therefore if you splash yourself, there will be less injury. No matter what state the oil is in, your best bet for a trustworthy reading comes if it's cool.
Understanding Viscosity and Temperature
Viscosity refers to the thickness of the hydraulic fluid. It is important to use the right viscosity since the fluid has to be thin enough to lubricate remote internal components while at the same time have the required thickness to function effectively at lower temperatures.
For hydraulic fluid to function properly it must remain incompressible so it can transmit power within the components of the excavator. If you use fluid with improper viscosity, you risk the formation of air gaps. These air gaps will cause your components to work harder, which will lower their operating performance and may cause them to break down prematurely.
The viscosity index (VI) serves as a metric to gauge the variation in viscosity of hydraulic oil in response to temperature fluctuations. A hydraulic oil possessing a low viscosity index will experience a more pronounced alteration in viscosity with temperature changes compared to one with a high viscosity index.
Temperature extremes significantly impact hydraulic performance, requiring careful viscosity selection based on operating environment and seasonal variations.
Maintenance Tips and Best Practices
High-quality fluids help your excavators operate properly and prevent thermal as well as oxidative breakdown. Quality fluids can also minimize soot-related viscosity and premature wear of vital components. You should avoid using the cheaper lower quality fluids or oils since they may contain additives that can't withstand high-duty cycles.
To ensure your excavator is protected, you also need to schedule an oil sample program to detect any impurities or contaminants in the oil. Change fluid annually or as directed in the manual. The used fluid test helps identify potential issues before escalation requiring expensive repairs.
Keeping fluid clean through regular hydraulic filter changes extends fluid and excavator lifetime. Catching issues early proves more cost-effective than dealing with neglected maintenance over time.
Good hydraulic oil maintenance starts with scheduled checks. Frequent top-ups may indicate hydraulic leaks that must be addressed to prevent fluid loss and equipment damage over time.
Consequences of Improper Maintenance
Risks of Low Hydraulic Oil
If a hydraulic pump operates without an adequate amount of oil, cavitation will occur (also referred to as running dry). This will damage the internals of the pump.
In a 'Gear' style pump; the gears, body, thrusts and shaft may become damaged due to excess friction. In a 'Piston' style pump; the rotating piston group and valve plate will become damaged due to excess friction.
Low hydraulic fluid levels can have several adverse effects:
Loss of Pressure: The hydraulic system relies on a certain amount of fluid to maintain proper pressure. If the fluid level is too low, the system may not generate enough pressure, leading to sluggish performance and potential failure of critical components.
Increased Wear: Insufficient lubrication and cooling can accelerate wear on the pump, valves, and actuators, causing parts to deteriorate faster and requiring more frequent repairs or replacements.
System Overheating: Low fluid levels reduce the system's ability to absorb heat, leading to overheating.
Common Leak Sources
The rotary distributor - also referred to as a swivel joint - can be the source of hydraulic oil leakage in center of a 360 excavator (you might be seeing oil around the machines slew bearing). Deterioration of sectional seals within the rotary distributor are likely the culprit here.
Another common cause that may be the parent to each of the above: over pressurization the hydraulic service or excess return pressure.
Check the swing drive oil and final drive oil levels as well. Try to get a little oil out of the final drives and make sure it isn't milky. If it has been in water or soupy mud you can get a little water in them.
Conclusion
Maintaining the proper hydraulic fluid level in your excavator is crucial for ensuring its efficient operation and longevity. Follow the proper processes to the letter. And only use the recommended fluids and lubricants as specified.
Do that, and your digging excavator will be hard at work for many years. Stray from that path of excellence, and you'll be replacing components a lot sooner than your manufacturer predicts.
Hydraulic fluid is vital for keeping your excavator running smoothly. Dirty or incorrect fluid can cause wear, overheating, and system failures. Regular checks and using the right fluid help your machine last longer and work more efficiently.
By following the above steps, you will be able to maintain your equipment effectively and safely. Always prioritize safety, and with proper precautions, you can refer to the above guidelines and user manual to add hydraulic fluid to the excavator, which will be of great help.
If you are an experienced individual, consider adding hydraulic fluid as a regular task to prevent unexpected failures.