How do I change Hydraulic Oil?

When changing out the hydraulic oil in mobile hydraulic equipment such as an excavator, what is the best way or process to remove all or as much oil as possible?

With any oil change the goal is to remove as much of the old fluid as possible. There are some steps you can take to maximise the amount of oil coming out of the system.

One of the best things you can do is to ensure all of the hydraulic cylinders are in their closed position. When they are closed very little oil is left in the components. The same is true for any other expansion component located within the hydraulic circuit.

Depending upon the hydraulic system’s complexity, there may be more than one drain port from which to drain oil. The main reservoir should have the largest drain port, which will help facilitate the quickest draining method of the system. However, some components may have individual drains to remove fluid from or other low areas of the circuit again to also drain from.

Another excellent way to drain the system is to pull any return line filters. These filters can hold a significant amount of oil, and by removing them, you also open the return lines for additional draining.

Whenever a drain is performed, air must be allowed into the circuit to permit any oil to drain. All breather ports should be fitted out with breathers to strip incoming air of moisture or particulate sludge or debris. A good desiccating breather is a must to help reduce or eliminate contaminant.

Most different Original Equipment Manufacturers (OEM’s) will have their own standard procedures for the oil change process. While they may vary from model to model, whilst they should always be consulted, the same basic elements will usually exist.
  1. Draining the Oil – Remove the drain plug, replace the filters and refill with new oil. Gravity will do the majority of the work in draining the oil, but there are other options to help expedite the process.
  2. Portable Filters – Portable filter carts can be used not only to filter incoming oil but also to pull out old oil. By using a filter cart to drain the oil, you can reduce the time it takes to remove the oil as well as fill the system without having to open the reservoir to the environment for as long a period. If using a filter cart to drain the oil, be sure to bypass the filters. Finally, don’t forget to save the filters for topping up or refilling the compartment.
  3. Changing the oil – There are only two conditions that require a complete hydraulic oil change, degradation of the base oil or depletion of the additive package. Because there are so many variables that determine the rate at which oil degrades and additives get used up, changing hydraulic oil based on hours in service, without any reference to the actual condition of the oil, is likely to be based on a lot of guesswork and given the current price of hydraulic oil, changing oil which doesn’t need to be changed just based on service hours is probable the last thing you want to do. On the other hand, if you continue to operate with the base oil that has been or is degraded or additives have been depleted, you will compromise the service life of every other component in the hydraulic system. The only way to know when the oil needs to be changed is through oil analysis.
  4. Changing the filters – A similar situation applies to hydraulic filters. If you change them based on schedule, you’re changing them either too early or too late. If you change them early, before all their dirt holding capacity is used up, you’re wasting money on unnecessary filter changes. If you change them late, after the filter has gone on bypass, the increase in particles in the oil quietly reduces the service life of every component in the hydraulic system this will cost you a lot more in the long run. The solution is to change your filters when all their dirt holding capacity is used up, but before the bypass valve opens. This requires a mechanism to monitor the restriction to flow or pressure drop across the filter element and alert you when this point is reached. A clogging indicator is the crudest form of this device. A better solution is continuous monitoring of pressure drop across the filter.
  5. Running too hot – Very few equipment owners or operators continue to operate an engine that is overheating. Unfortunately, the same cannot be said when the hydraulic system gets too hot. But like an engine, the fastest way to destroy hydraulic components, seals, hoses etc as well as the oil itself is running the equipment at to higher temperature during operation. How hot is too hot for a hydraulic system? Well, It depends mainly on the viscosity and viscosity index Hydraulic Oil Data sheet HVI Hydraulic Oil Data sheet the rate of which change in viscosity with temperature occurs in the oil, and the type of hydraulic components in the system. As the oil’s temperature increases, so its viscosity decreases. Therefore, a hydraulic system is operating too hot when it reaches the temperature at which oil viscosity falls below that required for adequate lubrication.Apart from the issue of adequate lubrication, the importance of which cannot be overstated, operating temperatures above 82 degrees Celsius damage most seal and hose compounds and will accelerate degradation of the oil.
  6. Using the wrong oil – The oil is the most important component of any hydraulic system. Not only is hydraulic oil a lubricant, it is also the means by which power is transferred throughout the hydraulic system. It’s this dual role which makes viscosity the most important property of the oil, because it affects both machine performance and service life of your equipment. Oil viscosity will largely determines the maximum and minimum oil temperatures within which the hydraulic system that the equipment can be safely operate. If you use oil with a viscosity that’s too high for the climate in which the machine must operate, the oil won’t flow properly or lubricate adequately during cold start. If you use oil with a viscosity too low for the prevailing climate, it won’t maintain the required minimum viscosity, and therefore adequate lubrication, on the hottest days of the year. But that’s is not all, within the allowable extremes of viscosity required for adequate lubrication, there is a narrower viscosity band where power losses are minimised. If operating oil viscosity is higher than ideal, more power is lost to fluid friction. If operating viscosity is lower than ideal, more power is lost to friction and internal leakage. Using the wrong viscosity oil not only results in lubrication damage and premature failure of major components, it also increases power consumption. So wherever possible follow recommendations of the machine manufacturer, but remember to take conditions into account.
Common Mistakes
  1. Believing hydraulic components are self-priming and self-lubricating – You wouldn’t start an engine without oil in the crankcase, yet this is often seen happening to a lot of high-priced hydraulic components. The fact is, if the right steps aren’t followed during initial start-up, hydraulic components can be seriously damaged. In some cases, they may work OK for a little while, but it is to late, the harm incurred at start up will eventually lead them to premature failure. so knowing what to do and remembering to do it is important.
  2. Not getting an education in hydraulics – The purpose of this suggestions is to show that if you own, operate, repair or maintain hydraulic equipment and you aren’t aware of the latest hydraulic equipment maintenance practices, a lot of money could slip through your fingers.
  3. How do I replace Hydraulic Oil with Biodegradable?
Excavator Maintenance:

Here are 5 compact excavator maintenance recommendations

1. Track Tension. One of the most overlooked service points on compact excavators is track tension. A lot of compact Excavators have rubber tracks, which need to be kept properly adjusted to maximise equipment longevity and this in turn helps minimise wear on the track and its components. A track running loose will accelerate wear causing unnecessary downtime and put a stop to production with the need to reinstall a new track. But take care with torque and tension as a track running too tight will cause the material to tear or split and will greatly increase wear on the other excavator system and components, including traction motors, sprockets and front idlers. Operators should always refer to the operator’s manual and check track sag measurement on a regular basis to ensure the track tension is just right.

2. Grease. The lifeblood of all pins and bushings, grease is another common service point often forgotten about.  As a general rule of thumb, all pins and bushings should be greased daily. The operator’s manual will help with identifying each grease point and providing recommendations for quantity and grade of grease. If there are multiple operators using a single machine, it might be a good idea to mark less obvious grease points, such as the turntable bearing, with orange marking paint around the grease nipple as a reminder to all users. Midlands Lubricants have an excellent range of Grease to enable correct protection of your equipment. As with under greasing please take care not to over grease as this can also be problematic. One to three shots of grease is typically more than enough to do the job.

3. Propel Drive Gearbox. One of the most vital components to a machine’s performance, the propel drive gearbox often gets neglected when it comes to servicing. Many times, gearboxes are covered in mud, with the fill and drain plugs not visible so operators and service personnel rarely notice them. However, gearboxes require an oil change at around 1,000 hour intervals, depending on the manufacturer. Gearboxes may be small, but they are still expensive to manufacture because they have the same internal parts as their larger cousins, just on a smaller scale. Typically holding between a 1/2 to 1 quart of oil, they can be changed pretty quickly in most cases, so it is a small investment that will pay off in the future. Midlands Lubricants supply a wide range of Gearbox, Axle, Differential and Transmission Oils suitable for all OEM Excavator, Digger and other heavy equipment machinery.

4. Hydraulic Oil Change. Hydraulic oil can be misleading because although it may look clean, just like engine oil, it breaks down, loses its viscosity and its ability to hold contaminants in suspension, a process that helps protect all moving parts in the system. Hydraulic systems are designed to precise tolerances and most hydraulic failures can be traced back to contaminated hydraulic oil or even the wrong hydraulic oil.

One of the many important functions hydraulic oil performs is that of absorbing moisture in the system and keeping it away from the hydraulic components. You may not think that rust could be a problem in a sealed hydraulic system that is always full of oil, but it is. Don’t make the mistake of thinking that just because hydraulic oil looks good, that it is. By the time hydraulic oil becomes cloudy, it is far beyond the point where it should have been changed and has lost much of its ability to protect the components in your hydraulic system properly. Most equipment manufacturers suggest a hydraulic oil change interval in the 2,000 to 4,000 hour range, but every machine is different. Your operator’s manual will provide you with a specific servicing timetable and oil requirements to follow Midlands Lubricants Hydraulic Oil range.

5. Keep Records.
 Record keeping may the most tedious and time consuming of all tasks, but keeping up to date with service records and invoices for oil, filters and repairs can provide invaluable information in the future when evaluating the service life of your machine. All equipment will come to the end of its service life eventually and if you keep accurate information, it will give you a baseline to evaluate the performance of the machine and help you make an informed decision about whether to buy the same manufacturer’s product again or make a switch to a different brand.

So the next time you service the engine oil (Midlands Lubricants 15w/40 Engine Oil Range) and fuel filter on your compact excavators, check your operators manual,  take a little extra time and money, service your machine properly and always document the service. This is, hands down, the most cost-effective way to ensure minimal downtime in the future. In the long run, you and your bottom line will be glad you did.

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