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Working with hydraulic machinery involves a certain degree of trouble shooting and problem solving, even people who operate the equipment and are not involved in maintenance and repair, should have some basic knowledge of what can go wrong and what to look out for. When it comes to diagnosing and solving problems with hydraulic machinery there are several things that should be checked, and just as many tips and tools to help you do so.
Firstly, if a schematic diagram of the equipment is available this is a very handy tool for fixing problems. It may be obvious that a seal has gone somewhere along the line, but without a schematic diagram it can be a long trial and error process of finding, then changing every seal in a process of elimination. On very complicated and large hydraulic equipment with multiple hoses and cylinders it helps to be able to quickly locate each junction, especially if the presentation of the issue points to where the problem may be located. The schematic diagram also allows you to identify the potential causes of a problem, and prioritise them by likelihood, meaning less time is spent speculatively replacing parts at random and more time is spent actually investigating the most likely causes and addressing them first.
A flexible powerful light is also very useful for finding faults in hydraulic equipment, as some labels and parts may be out of the way and hard to see or read. Big torches are powerful but not so good for tight spaces, so a fibre optic light is a good investment. Magnetic dropper tools are also very handy when disassembling complex parts in situ, as if a small part falls into a reservoir or cylinder it means taking the whole thing apart to retrieve it, and in the worst cases replacing that part entirely, which can be very costly. A small magnet on a telescopic rod may be cheap and small, but can come in very handy indeed.
Once the potential problem has been diagnosed, the offending component needs to be removed and inspected for faults. Compressed air and air guns are great for cleaning off parts and for inspecting the integrity of valves. Similarly, automotive brake and clutch cleaner is an invaluable tool for cleaning greasy and contaminated components, without the need for pressure or rubbing that could otherwise damage the part. If the suspected part turns out not to be the culprit then it needs to be clean and free from contaminants when it is replaced, otherwise further issues could arise from dirty parts being replaced in the machinery.
When disassembling parts it is imperative that all components are inspected and kept visible; a lost screw or other vital part can cause bigger problems than the initially broken part if it is hard to replace. Using heavy white paper to lay out the components keeps them in sight, in order and makes it easy to see oil leaks, as well as keeping the oil off other things in the vicinity. It is also handy to be able to make notes on the paper, circling components that are okay and crossing next to ones that are broken.
Having a small tool set to hand is vital for repairing faults, and it is worth getting any specialist tools that the hydraulic machinery may require so they are to hand when needed. Spare seals are also vital to have on board, as these are often the cause of leaks but should be replaced when inspecting and repairing faults, even if they are not to blame. It is a good practice to replace these if they are removed for fault finding, as they could be compromised and stretched from being removed.
Join us in part 2 for more hydraulic trouble shooting tips that are firmly in the 21st century.
Smartphones have revolutionised the way we work and live in a very short space of time; “there's an app for that” may have been the slogan that launched a thousand apps but it's definitely true, whatever you need help with there is an app designed specifically for that purpose. Some apps are designed to fulfil a particular function that can be applied over several uses, such as torch apps, compasses and even scales (which use the ability to sense pressure to weigh items on the phone screen).
Big Magnify is a free app that magnifies objects captured through the camera up to five times the size. Some phone cameras may let you do this with the phone already, but many do not go to this scale, so this app would be useful for anyone who works with small components, some of which may be hard to see if they are out of the way. Using this app in a tight space will allow you to see a detailed zoomed in picture of the potential problem, without having to access the part or disassemble is speculatively.
Hydraulic equipment does generate noise, and excess noise may be the first indicator of a problem. Using Decibel Meter Pro when you start using equipment for the first time allows you to record and store the normal operating levels of a particular piece so there is a baseline record. If the equipment makes more or less noise than it should the same app can be used to record the change, which may help diagnose the problem. Whilst this app is not free to download, at around 99p it’s a bargain for anyone who regularly works with loud equipment.
For those who use and repair hydraulic machinery outside, the free Metal Detector app is a lifesaver if you drop a small part in the grass. It may seem like a strange app to develop, but it works well enough to locate missing parts and is a lot quicker than finding a magnet and then dragging it around the area, hoping it will pick up that tiny part. It's also incredibly useful for locating any lost metal object at home and whilst out and about; and if you still put a coin in your Christmas pudding you can use this app to ensure you're the one that gets the lucky piece!
Convert Free is a great app for anyone working with formulae and numbers, as it can convert a huge range of measurements accurately. It takes away the need to remember conversion formulae and does the work at the touch of a button much more easily than using the calculator on a smart phone. Although this app is not specifically aimed at hydraulic engineers, the Hydraulic Engineer app is. It contains some of the same features as the conversion app, but has 300 conversion formulae for hydraulic power engineering as well as 60 area formulae. There are also actuator, hydraulic tubing, pump and induction motor selection tools, making it a worthwhile investment.
Another app designed specifically for hydraulic engineers is the Hydraulic Troubleshooting app, which is a free download. This app contains a technical bulletin library explaining some of the common problems, as well as a video library giving detailed visual explanations of these issues. The troubleshooting section of the app is a ten step program that guides you through the quickest process for diagnosing and solving most hydraulic problems. The idea is that by the end of the process the problem should be resolved, and if not it gives the user an action plan to follow in order to get the issue fixed.
Are there any apps, hydraulics specific or not, that you have used to help fix a problem or that make your job easier in any way? Please share them in the comments below.
In the first part of this blog we covered a range of common hydraulic symbols, explaining how they formed part of a circuit diagram along with their various functions. We continue where we left off, focusing on common hydraulic valves.
The pressure control valve comes in two basic forms; direct acting and pilot operated and the main function of these is to control the flow rate or its pressure. As there are a number of different types of pressure control valve which deal with variations in pressure their symbols can appear very similar. A good way to check which variant is used in a system is by the location of the valve in a hydraulic circuit.
The directional control valve is responsible for controlling hydraulic fluid flow. The spool of the valve works with the valve body which opens and closes the internals to control fluid flow.
- Actuators are always responsible for the push and never the pull of spool
The hydraulic check valve works to prevent flow in a certain direction. A spring in the check valve enables the valve to open but only when the pressure is exceeded. Reverse flow can be attained by the valve opening under the influence of pilot pressure. This is usually the case if one was looking to hold the pressure in the hydraulic cylinder.
In order for a hydraulic system to store its fluid a reservoir must be employed and these come in various forms including closed and vented tank forms.
Vented tanks are more commonly used in general applications with the closed variety mainly used on offshore and aviation industry applications.
A hydraulic cylinder operates by generating mechanical force through hydraulic power. The cylinder illustrated above is a typical double acting welded end variety and, having two ports, can be powered in and out.
Ever tried to decipher a hydraulic circuit diagram and make sense of its symbols? Our blog will help you to understand the meanings and functions of the common ISO1219 hydraulic symbols.
As there are so many possible combinations of system parts and functions possible, we look at the base component circuits that make up a typical hydraulic power unit.
A hydraulic pump typically comes in either a fixed or variable form with the variable version allowing adjustments in flow rate and outlet pressure. They both have the same aim though and that is to pump oil from the hydraulic reservoir back into the system.
• Hand pump – These pumps are handheld mechanical devices which pump high pressure fluid in one direction
Filters are an essential part of any system as they help filter our particulate from fluids and, in turn, they keep components in good shape and the system running effectively. They come in different sizes, with some in cases and functions and can be placed almost anywhere on a hydraulic unit if they are of the pressure filter type. Another popular type of filter is the return filter when filter oil is deposited back into the reservoir.
All in all, filters help to maximize the service life of a system provided they are changed at the specified manufacturer recommended intervals.
The role of a pressure relief valve is to transfer fluids from areas of high pressures to those of low pressures. This most likely involves the tank.
In hydraulic systems, a cracked piston-pump or motor housing is something that is considerably more common than many engineers imagine.
Usually this situation is caused by a case-drain line that is either restricted or blocked; sometimes the case drain line is not even attached. In this particular scenario, the pump or motor housing is transformed into a pressure vessel, something that it’s not designed nor intended to be. In fact it’s likely to just go bang! In addition blocked filters can also restrict the drain line and can also lead to cracked housing.
However, you wouldn’t be held to blame for thinking that a cracked hydraulic piston housing would be caused by a failure in the pumps rotating group. Although, in reality, this is something that will rarely occur.
Connecting a flowmeter to measure the internal leakage of a pump or motor case drain line can achieve the same effects if you omit to set the loading valve to the open position. The housing will fail very shortly after starting-up. It’s not a joke, it has happened before and it’s not something that you will want to have to deal with.
Hydraulic systems don’t work well with too much pressure
If there is leakage that surges inside the pump or motor case, and the filter will not allow it to escape, the pressure can be far too much for the housing – resulting in a crack. It may even blow out its seal. Even if this doesn’t happen, there is likely to be some form of mechanical damage from the high pressure.
There are a few issues with pressure, not just cracking but these results can occur too:
· When there is high case pressure, there’s likely to be excessive load on the shaft seal lip. This can lead to a groove wearing in the shaft and then leakage occurring. However, if the pressure is very high then it’s more likely that there will just be complete failure, without oil there will be inadequate lubrication and it will all go horribly wrong.
· The piston-ball and the slipper pad socket will be affected by high pressure on axial piston pumps. The slipper may even separate from the piston, the failure resulting from this can be catastrophic.
It’s very important to install the correct type of filter in hydraulic systems. For example, putting a depth filter on a drain line would not be a good idea and is not recommended.
Hydraulic engineers and designers have long been facing uncertainty over the future of hydraulic power in an increasingly electrified world. The replacement of hydraulics with electrical actuators and components in vehicles especially has caused unease over whether hydraulics truly has a place in effecting motion as technology marches forward. With the introduction of the Internet of Things (IoT), a truly connected network of equipment, household appliances and even lighting or heating systems, hydraulic power seems outdated, and likely to be replaced by electric alternatives as the technology improves unless the new generation of designers embrace the benefits of hydraulic power.
Hydraulics still has many clear advantages over electric power; load bearing capabilities and predictive maintenance are just two of the benefits of using hydraulic power and easier troubleshooting and repair underline the plus points of hydraulic versus electrical power. It is obvious, however, that for hydraulic power to survive and compete it must integrate seamlessly into electrical circuits so that there is no reason not to choose a hydraulic component over an electrical one, solely on the basis of ease of integration into the rest of the system. Many hydraulic power packs now, including the ones produced by Hydraproducts, are designed to fit with electrical circuits and to be used with electrical power, translating a small amount of electrical power into a much larger hydraulic force, without any risks of high voltage electrocution or shorting out a circuit under increasing loads.
One of the most understandable facets of the IoT is the unmanned warehouse. Already in trial by Amazon (using drones) and some Chinese companies (using robots running on a grid matrix), these automated warehouses need minimal human staff, with even deliveries being accepted by robots using RFID tags. The central processing office can oversee the delivery, but no one needs to physically sign for a consignment as this can all be done through sensors. Moving new stock to the right location within the warehouse is done through robotics, and the incorporation of electrohydraulic components means even heavy items can be moved and lifted into place on shelves. Sensors ensure that the location of each item is logged, and this data can be used to create an automated picking list for the same electrohydraulic robots to compile an order. Electric actuators may be used for warehouses that only deal in lightweight stock, but for car parts warehouses and other stockists of heavy components the extra power that hydraulic components offer is essential for true automation.
If nothing else makes hydraulic components an attractive choice, then the ability to scale up power and force through the intelligent use of hydraulic power certainly does. Electric alternatives may be getting cheaper and are undoubtedly easier to wire into a circuit than traditional hydraulic units, but the marriage between electric and hydraulic power makes perfect sense for fully capable robots that can cope with lifting and transporting items of all sizes and weights. The replacement and maintenance involved with fully electric systems is comparable to that of an electrohydraulic system, but it can be much harder to pinpoint the exact cause of a problem without careful study of the wiring schematic and an understanding of the original design. Hydraulic components, by comparison, are easier to fix for those who were not involved in the design process and given that engineers and maintenance people generally are not involved in the specification of a system, it is intelligent to have a system that can be fixed more easily.
The IoT is not confined to commercial and industrial applications, however, and in part 2 we look at the uses in the smart home.
Hydraulic filtration is a vital component of keeping a system running smoothly.
For example, did you know that up to 75% of failures with fluid power can be attributed to contamination? With the use of hydraulic filters, contamination damage can be significantly lowered which can not only cut down on expense but lower that 75% drastically.
If you’re looking to save costs from less downtime then it’s also time you looked into what a difference hydraulics filtration can make for extending the life of your equipment. Running your system optimally is essential when it comes to cost saving, but protecting its longevity is also a critical element in running any business efficiently.
Muck and dust can destroy a hydraulic system, that’s why it’s essential to make the best use of hydraulic filters. You wouldn’t even be able to remove that dirt yourself, as it’s likely to be dust that is so fine that you won’t be able to see it without the use of a microscope. Dirt has the same detrimental effect as sandpaper or gravel and not only will generally deteriorate the system, but it could even destroy it.
However, through the use of a hydraulic filter system you will be able to maintain control over the level of contamination and by doing so reduce the failure of systems by as much as 75% just be removing that dirt.
Hydraulic parts are expensive. Combine that with down time and having to keep engineers on hand to fix worn components and that’s a lot of expense to deal with. Putting filters into place can even save costs by increasing how long the hydraulic fluid will last.
Degradation of fluid – hydraulic fluid that contains fine metallic particles can degrade rapidly through chemical breakdown. Without protecting against this, there could be issues such as slippage, internal leakage, corrosion or sticking parts.
Scoring of surfaces – this can occur when particles get trapped between surfaces of seals
There’s no doubt about it, but …
· System performance is affected by dirt levels
· Hydraulic filters can control levels of dirt. Without using this management method, the system will get dirtier and dirtier until it fails.
In fact, hydraulic filters are the only way to control how much dirt is in fluid. Without them you will be forced to change out the hydraulic fluid regularly, which can be a time consuming and costly event.
Hydraulic system dirt particles are incredibly small. In fact, they are so small that they cannot be seen by the human eye – and 98% of hydraulic fluid has some dirt in it.
Engineers have found that when it comes to size of particles in samples taken from operating systems, the smaller the particles, the more dirt there is in the system.
So where do these particles come from that we have to work so hard to deal with?
In order to have an idea of what goes on inside the closed system, let’s examine where these particles come from.
Instead of enjoying the typical 20 gpm that is the measurement of a pumped flow from a 2000 psi system, you can expect to see something in the region of just 10 gpm. Although your pump will still produce for you, you’ll discover that the degradation results in just 50% efficiency and you should als be prepared to experience extra heat and other unwanted issues.
As with any hydraulic system, there is an optimum level of cleanliness, but there is a point where you cannot get any better performance out of the system by improving the quality of the fluid. However, with the use of hydraulic filters you should be well set to extend the life of your machinery.
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