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It’s no secret to hydraulic system engineers that implementing proactive maintenance takes both time and money. It’s for this reason that it’s important to get a grip on whether the tasks involved are worthwhile in terms of return on investment as part of the ongoing engineer’s challenge of increasing reliability.
Here at Hydraproducts we have debated this subject matter at great length and we have settled on using the Reliably-centred Maintenance (RCM) approach with a set of questions to understand more with regards to our maintenance investment decision making. The questions are:
· Is the machine acceptably reliable?
· How critical is it that the machine is operating fully?
· Will improving the maintenance of the machine prove to be a cost effective exercise?
· Is it worth investing in redesign of the machine to improve reliability?
· Is the machine and its components expendable and if so, should it be run into the ground?
RCM has now been established in many engineering practices, but it’s most prominent in the airline field. Performing extensive maintenance on all the systems of a large airliner would not make sense as it would result in the aircraft spending more time in the hangar than it would in the skies making revenue.
However, it’s critical to have a safe airliner and therefore, the maintenance process must not compromise safety in the resulting reliability.
Although there are a lot of questions that are more ‘what if’ by nature, they can help to ensure that the right maintenance gets performed, giving the best possible results.
Running through the RCM process on any complex hydraulic system can be both time-consuming and arduous. It’s a system that is most effective when performed on a fairly new machine with unknown failure causes. In summary, being able to detect problems early and therefore be able to extend the life of a hydraulic machine can save time, money and downtime. As engineers it’s our role to find a way to detect these problems and on some occasions, an RCM type approach can prove to be a valuable aid.
Are you interested in what can cut costs when it comes to Hydraulic Power in your business?
We can only imagine that the answer is ‘yes’ as most of us are. Well, we’ve got some good news for you. Today, we’re going to look at what the most common reasons are that hydraulic components fail, even those that have not been in service for long.
These points are worth making a note of:
1. Oil changes. It’s not necessary to keep changing the oil unless you have one of thes2 following conditions occurring.
The oil has degraded so far that the original additives have changed its makeup. Changing oil just because you feel it’s about time it’s changed is going to cost you a lot of outlay as oil is expensive. The larger your reservoir, the worse off you’ll be. However, if you keep operating your system with degraded oil, then that could cost you even more. Even changing the oil based on how long it’s been in service isn’t going to help. Oil needs to be analysed to fully understand its condition.
If you discover that your oil is contaminated with particles, the more economical manner to deal with this is to remove the particles through filtration.
So in summary, only change the oil when the additives have been depleted and the base oil is useless. You will have to perform oil analysis to make your decision.
2. Filter changes. It’s the same story with hydraulic filters. Changing them based on hours in service could mean that you’re too early or even too late. Early brings about waste as their capacity is not reached and you’ll be throwing away an unused amount of filter time. Changing them late is also an error as the particles will not be removed from the oil and therefore, it could lower the lifespan of each component in the entire hydraulic system.
The most effective approach is to only change filters once they have become full of dirt, but prior to the bypass valve opening. This may require a mechanism to be added that will monitor the pressure and deliver an alert when a point is reached. A clogging indicator is one of the most basic methods of handling this. However, continuous monitoring of pressure drop through the use of a differential pressure gauge or a transducer is the optimal solution. In summary, changing filters on hours is not maintenance effective, or cost effective.
3. Heat. If you’re driving along and you notice that your car engine is overheating, you would most likely stop. Most equipment owners won’t run an engine that is overheating. They know it’s going to cause problems. However, the same cannot be said about operators of hydraulic system.
Just as with a car, running an overheated engine is the quickest way to destroy hydraulic seals, hoses and other components. How hot is too hot? The answer depends on the viscosity of the oil in addition to the hydraulic components. Viscosity lessens with increasing temperature, so the answer is when the temperature is high enough to stop the oil lubricating as it should.
When it comes to hydraulic components, it’s worth noting that a vane pump needs more viscosity than a piston pump would. If you have a vane pump in your hydraulic system, then you’ll want at least 25 centistokes to be maintained.
Temperatures over 82°C will cause damage to seals and hoses in addition to accelerating the oil’s degradation. Never allow your hydraulic system to operate above 82°C with a viscosity lower than 10 centistokes.
4. The wrong oil. The most important element of any hydraulic system is always the oil. It’s what keeps everything lubricated and it is also what transfers the power. With these two major tasks to handle, keeping an eye on viscosity is a must.
The viscosity of the oil is what will determine the temperature at which the system should be run. You may have heard this referred to as temperature operating window or TOW. A temperature that is too high will prevent the oil from flowing or lubricating as it should. Oil that has a viscosity that is too low will not deliver adequate lubrication either. Keeping an eye on this will also ensure that you power isn’t lost due to either internal leakage or mechanical friction.
You don’t want increased power consumption as it will cost you more. The best way to handle this is to check what your machines temperature operating window is and to ensure that your machine operates within that window at all times. We won’t go into how to do this here, as it’s rather complex, but it’s something that does need to be addressed.
5. Filter locations. There are two locations for filters that cause the most problems – the piston pump and motor case line and the pump inlet. You may have a strainer attached to the pump inlet to collect any ‘garbage’ in your oil, but this oil is being drawn from a reservoir, not somewhere where there should be any garbage.
The pump inlet is also positioned off the bottom, so there should not be a lot of dirt passing through. By placing filters here, it can affect whether you get maximum pump life. If there is any form of restricted intake, it can reduce the lifespan of the gear pump by as much as half. Hydraulic pumps are not built with ‘sucking’ in mind! The way to handle this is to remove any suction strainers or depth filters on either the pump inlet or the piston pump.
Applying these points should be helpful to any hydraulic system operators and should deliver methods to save yourself and your business great expense.
Until next time..
The routine maintenance of a hydraulic system may be the responsibility of a staff member without a background in the operation and repair of hydraulic machinery, who should follow a strict procedure with a checklist to ensure tasks are carried out in the right order and using the correct equipment. The replacement of hydraulic fluids is one area where extra care must be taken to use the right oil, as the average layperson may not distinguish between hydraulic oil and engine oil, or even fuel. Mistakes like this can be costly, and when equipment breaks down because of avoidable oversights it can undermine the integrity of the whole company; one silly mistake is usually a sign that other things are being overlooked.
Maintenance procedures should be written by an experienced engineer, possibly working with a technical writer, to produce a document that is easy to follow and contains all the relevant information. Procedures should be tested several times to ensure there is no room for interpretation of instructions – ambiguity in procedural documents can lead to poor practises. It is worth adding pictures to a checklist, to further enable staff to comply with the procedure. Some people take in information better when it is presented in a visual format than in words, and vice versa so by using both forms of communication the document will be comprehensible by non-hydraulically savvy staff.
There is one important ingredient in a checklist for hydraulic machinery maintenance and operation, and that is the “idiot test”. This refers to a step in a procedure or clause in a contract that clearly shows whether attention has been paid to detail. Some common examples are rock stars insisting on a bowl of sweets in their dressing room with a certain colour removed. This is not, as it appears on the face of it, brattish behaviour but a clever way of knowing whether or not standards have been followed throughout. If a simple task, like removing all the yellow sweets from a bowl, has not been done properly it is indicative of carelessness. The same concept applies for exams where the final instruction is to only answer one question – students who are not paying attention and are not interested in the bigger picture will answer every question before reading the last instruction.
If you want to ensure that your hydraulic equipment is being used and maintained to the correct standards you can incorporate an “idiot test”, like having to note down the volume of hydraulic fluid that has been added, or signing materials in and out of a book. These are easily checked by a supervisor without arousing suspicion, and failure to complete the “idiot test” lets you know to check over that person's work and offer extra training.
Of course, it is desirable to always have hydraulics savvy people undertaking maintenance and in some cases, the operation of equipment with a hydraulic motor, but this cannot always be achieved. Training courses in the operation of hydraulic equipment are essential for health and safety, but your ‘in house’ policies can always be tightened and tweaked to close any potential holes in procedure, and engineer out bad practise and common problems by refining your processes.
Keeping overheads low is a fundamental of good money management in business. When your supervisor tells you that the company are pulling in its purse strings and he wants you and your department to help, it’s might not always obvious as to how you can cut back on costs, in particular in this day and age of expensive parts and fuel.
One approach is to save on fluid. Although your hydraulic system may not even be leaking, if you could keep your oil in service longer than usual, whilst not putting your machine at risk of damage, then you know you’re going to be his favourite employee this month.
Here’s how to do it:
Keep it inside
The most important thing is not to waste it. Although you may have a couple of slow leaks that are on your list to be fixed at some point, they are costing you more as every day goes by. The price of oil might be lower than it was, but it’s still pricey. Solving leaks comes complete with a cost reduction. If you don’t attend to them, then you’re affecting your department’s economy.
Keep it responsive
Keeping your oil within optimal operating temperatures offers many advantages. For one, it’s going to have a longer life. By allowing it to get just 10 degrees warmer, it will not have an extended life according to Arrhenius's Law. There will be negative reactions including oxidation. This is caused by air entering the system and hydrolysis – the presence of water. The warmer the oil, the more you’ll suffer from these.
In order to illustrate this – consider what happens when you have cooking oil at home. You could pour it into a cup and leave it on the side. It will take a long time to change colour. However, if you put it into a frying pan and heat it as hot as you can, you’re soon going to have a pan of darkened oil.
Some oils have anti-oxidant additives added. In addition you may want to consider installing a heat exchanger, increasing the number of filters and magnetic plugs and even going so far as replacing any copper or brass tubings under circumstances where the pressure rating is more than 10 bar.
If you do opt to use magnetic plugs, then ensure that there is regular cleaning of them. Otherwise the particles may be dislodged by any oil surge and then they will be back circulating around your system and causing damage. In addition, using the magnetic plugs will help to reduce the work of the filter.
Keep the water out
Water can damage oil. It can also compromise any additives in it. Take ZDDP which is an anti-wear additive, add water to it and you’ll find that it’s completely unstable.
Keep it clean
It’s difficult to keep hydraulic oil clean. Every time you access the system there is a chance that it will collect dust particles. It’s also likely that particles are building up from wear inside the machine. Certain metals are worse than others when it comes to increasing how fast hydrolysis and oxidation happen. These metals include iron, copper, lead and zinc in addition to water. It’s also likely that particles will attach themselves to any additives in the oil, which will lead to depletion of the additives.
In summary, gaining extended longevity from your hydraulic oil comes from good maintenance; keeping your machine leak-free, keeping oil at optimal temperature and clean. Don’t change it until the oil has degraded or your additives have extensively depleted.
Performing maintenance often and well will keep you in the good books of your boss. There’s nothing better than good filtration and the prevention of impurities to keep the fluid clean. You may also want to look at your oil storage system prior to oil being entered into the system. For example, keeping oil barrels horizontal can protect them from water collecting near the bungs. It will also mean that the bung is kept wet and therefore will be more effective as an airtight seal.
Let us know how you get on and if you have tips to share on improving hydraulic system economy, do tell.
Imagine being able to protect your mobile hydraulic system against fluctuating temperatures. The climate in the UK is varied and some say you can have four seasons in one day. The difference between a hot summer’s day and a cold mid-winter day is extreme, even in our temperate climate.
In this post we offer 3 easy ways to get the best out of your mobile hydraulic system – even in the opposing temperatures that are found outside throughout the year.
With the hydraulic systems of today being far smaller than they once were and relied upon to run at all manner of temperatures, it’s important to provide the best hydraulic fluid to enable easy operation – in particular for mobile outdoor applications.
As an engineer, you know how important it is to avoid down time and provide the right conditions to enable best performance, including out in the field
Here are our 3 pointers on knowing what to look for when choosing the right fluid for your hydraulic system:
Viscosity index is key. VI or viscosity index is an incredibly relevant factor when looking for an oil that can handle a range of temperatures. Seek a high VI and you’ll have an oil that will not be overwrought by temperature changes.
The advantages of a high VI fluid are that it’s possible to increase overall efficiency and prevent sluggish operation in addition to reducing leakage of internal pumps. Being able to maintain optimum efficiency in a wide range of temperatures will also help with diesel consumption whilst lowering the CO2 emissions.
Low temperatures demand high fluidity. Fluidity is essential in frigid temperatures. Your oil will flow more easily and this will aid a better start-up. Using the right fluid can cut warm up by 15 to 20 mins to just 3 or 4. It will also prevent component damage from a cold start.
High temperature oil delivers protection. Equipment that runs under heavy loads and has high pressure can result in oil become thin and therefore not provide the lubrication required to protect your machine.
In review, ideally the best oil to use is an all season fluid that will provide protection throughout the year.
We’ve always been a fan of predictive maintenance for hydraulic systems. It can save time, system damage, expense and downtime. If it’s not already embedded into your workshop processes, then we recommend that predictive maintenance is put right in there along with your inspection processes.
In this post we look at the categories that John Moubray uses in his Reliability Centred Maintenance II book to understand how predictive reasoning should be approached. This is then followed by an example of how it could be used to understand what’s happening with your hydraulic system by using your powers of reasoning.
Broken into these 6 major categories, these maintenance actions can save you expense, time and of course loss of productivity through downtime. What any engineer who works with hydraulic systems should focus on are:
1. Dynamic effects including the monitoring of vibration, pulses and acoustic emissions.
2. Particle effects including the monitoring of particles in the operating environments of the component – ie the condition of the lubricant.
3. Chemical effects: monitoring of the chemical elements in the components operating
4. Physical effects such as cracks, wear, fatigue
5. Effect of temperature
6. Effects of electrical
Although Moubray’s list does cover most of the hydraulic systems maintenance needs, it does not cover all and there are new techniques being discovered and devised continually that should be researched. The visual inspection is one of the most basic and necessary of all predictive maintenance techniques.
Putting this to the forefront, it’s important to look for the following during a hydraulic system inspection:
· Both the quantity and the quality of the hydraulic oil in the tank needs to be checked. The appearance should be bright and clear.
· Check for any leaks or weeps around the seals, connectors and component bodies.
· The surface condition of the tubes, pipes and hoses external.
· The cylinder rod-wiper seal condition needs to be checked.
· The cylinder rod surface. Look for scores, nicks and dents.
· The filter clogging indicator position.
· The readings of the operating pressure (test-points and gauges that have been permanently installed should be used)
· The operating temperature of oil (use either an installed thermocouple or a heat gun)
· Listen out for abnormal noises such as knocking and clicking
The success of predictive maintenance tasks depends on whether data is recorded and then how it is analysed, whether it’s collected through human senses or by using sophisticated measuring tools. It is then necessary to take actions that will either remedy the situation or avoid damage from occurring. The process for predictive maintenance is this:
· Data collection
· Analysis of data
· Predictive reasoning to ascertain possible future issues if maintenance is not addressed
As an example, you may prefer to perform an inspection of your system as part of your regular maintenance routine. You may discover that there is a noise that has increased in volume and that there is no longer a smooth cylinder movement with your actuator. There could be an interpretation of this even as there being issues with reliability and performance of the system up ahead including issues with lubricity. These are all issues to record and take note of for future analysis.
In addition it’s necessary to ensure that the interpretation of the data is in the right context. Perhaps your visual inspection reveals an issue with the filter being clogged. You may identify this from the clogging indicator. Although this would not normally be an issue, it is if the last time the filter element was cleaned or changed was just the day before. Although the data is the same, used through the filter of a different context, then your reasoning will be entirely different.
Summary. It’s important to identify issues in hydraulic systems so that action can be taken whilst the issue is still small. Predictive engineering offers this solution. It also makes it possible to refine your system so that you can avoid issues and enable your machine to have less downtime and expense. It’s truly worth getting into the routine of looking for issues early on.
Our engineers are focused on producing mobile hydraulic power packs. We provide insights into hydraulic system maintenance for those who have an interest. If you’re looking for a custom solution to your hydraulic system application needs, contact us today.
In this article we want to explain the ins and outs of hydraulic powerpacks. A vital piece of equipment that is used with so many machines we see every day.
In a nutshell, hydraulic powerpacks are self contained units that are used instead of a built in power supply for hydraulic machinery. Hydraulic power uses fluid to transmit power from one location to another in order to run a machine. It really is as simple as that.
So what do they look like?
In order to recognise and better understand hydraulic powerpacks, it is a good idea to get to know the key components. Hydraulic powerpacks come in many different shapes and sizes, some are very large and stationary whereas others are much smaller and more compact. In fact, some hydraulic powerpacks are so compact that they can easily be transported in a small van or even an estate car.
The only real way to identify hydraulic powerpacks is through its main components. No matter the size of the unit, all power packs will have the following; a hydraulic reservoir, regulators, a pump, motor, pressure supply lines and relief lines.
What do these components do?
It may be obvious to some but in this post we wanted to explain every hydraulic power pack component as simply as possible. So here goes.
First up is the hydraulic reservoir which quite simply holds the fluid. Reservoirs will come in different sizes.
Then we have the regulators. Regulators are vital as they control and maintain the amount of pressure that the hydraulic powerpack delivers.
Thirdly we have the pressure supply lines and relief lines. The supply line simply supplies fluid under pressure to the pump and the relief lines relieve pressure between the pump and the valves. The relief lines also control the direction of flow through the system.
Finally we have the pump and a motor. We will begin with the simpler component of the two, the motor. The motor is simply there to power the pump. Easy as that. Now the pump generally performs two actions. Firstly, it operates as a vacuum at the pump inlet and through atmospheric pressure forces fluid from the reservoir into the inlet line and then to the pump. It then delivers the fluid to the pump outlet and pumps it into the hydraulic system. We did warn you that the second part would be slightly more confusing.
So what is the function of hydraulic powerpacks?
Hydraulic powerpacks deliver power through a control valve which in turn runs the machine it is connected to. Hydraulic powerpacks come with a variety of valve connections. This means that you can power a variety of machines by using the appropriate valves.
Hydraulic powerpacks are relied upon by a range of different machines that use hydraulic power to do its work. If a machine is required to carry out heavy or systematic lifting then its likely it would need help from a hydraulic powerpack.
To make it easier for you to understand, we have included a list of trades that regularly rely on our powerpacks. On a building site you will see machines like bulldozers and excavators, which both need hydraulic powerpacks. But, it is not just on building sites that you will find these types of machines. Fishermen and mechanics both need hydraulic powerpacks too. If we did not have them then how would fishermen lift their nets or how would mechanics lift our cars?
When picking a hydraulic powerpack there are a variety of pumps and options to pick from and it is important to pick the right pack to meet your machines needs. It is also important to consider a pack that will help maximise productivity and minimise cost.
Many people will overlook the necessity of hydraulic powerpacks, but they really are vital to ensuring our society runs efficiently.
Do you need to maintain hydraulic powerpacks?
Yes you do and this is hugely important! Hydraulic powerpacks require regular maintenance to ensure they are working properly and safely and to help extend their life. Maintaining hydraulic powerpacks is relatively simple and includes checking the tubing, this can be for any noticeable problems such as dents or cracks. It is also vital to regularly change the hydraulic fluid and look at the reservoir to check for any corrosion or rust in hydraulic power packs.
What hydraulic powerpacks do we provide?
Generally we provide four different types of hydraulic powerpacks. You can pick from a standard powerpack, a mini powerpack, a micro powerpack or a bespoke powerpack.
The standard hydraulic powerpack uses a standard range of modular components and is ideal for the most demanding industrial applications. The mini powerpack is ideal for applications requiring up to 5.5kW. The micro hydraulic powerpacks were originally produced for mobility applications, so are great for when space is limited. Finally, if none of these seem to fit your needs then we offer bespoke hydraulic powerpacks ensuring your application gets the hydraulic powerpack it requires.
Finally, who is the genius behind hydraulic powerpacks?
The man behind hydraulics was Laissez Pascal. A French mathematician, physicist and religious philosopher who lived in the mid seventeenth century. Pascal made observations about fluid and pressure which led to Pascal’s law. Pascal's law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. Hydraulic powerpacks have been designed based on Pascal's law of physics, drawing their power from ratios of area and pressure.
So, interested in our Power Packs? Come on over to the main website and see what we can do for your Hydraulic Power Pack Needs .
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