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As everybody who works closely with hydraulic equipment and has to deal with failed components knows, some manufacturers have been known to try anything to deny warranty claims.
Of course, we cannot say that every warranty claim is legitimate, in some cases they are clearly NOT. However, when a component does fail ahead of time, it’s important to provide accurate and precise information. It’s not enough to blame the failure on ‘contamination’.
One of our clients told us a story about what happened to them when they returned to the manufacturer with a component issue. Our man wanted a warranty claim, but when he stated that the failure was caused by contamination, he was told that he couldn’t claim for a warranty on that cause.
So he decided to do his own research in his hydraulic and engineering books. His analysis proved that the failures were in fact not related to oil cleanliness or condition. So he took this information back to the manufacturer, from whom he received a verbal agreement with his scientific findings. But he still didn’t qualify for a warranty.
Although the manufacturer of the component agreed with his investigation into what had caused the breakdown, they were quick to state that it was actually an issue with the machine hydraulic circuit design that had caused this issue.
It was at this point that our client started to get quite miffed with the manufacturer. What annoyed him was that they were very keen to turn down the warranty but they were not making any strides towards giving a proper analysis of what had gone wrong with the component. It was only when our client did his own research that he found out what had gone wrong after many more of the components had failed. It cost him a lot of money.
The bottom line is that component end users should be given better information from manufacturers when there is a failure. If they were, then they would be saving themselves a lot of time and trouble and the manufacturers would gain a better reputation in the industry. It would be a step up in customer service. It would also save hydraulic circuit owners a fair whack every year too.
When you ask for a warranty to be honoured, we recommend that you go out of your way to provide as much info as possible, and there will be less chance that the manufacturer can back out of their promise.
Maybe we are being idealists in our ramblings about what could or should be happening in they hydraulics industry. Because we are a small company we go out of our way to help our clients. If they have an issue, we work with them to resolve it. If every manufacturer, big and small, operated in this way – hydraulic engineers would be more than satisfied in our opinion. Don’t you agree?
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 .
Hydraulics has been around for a very long time. But are you aware of how far it has actually come? You wouldn’t be alone if you responded with no. It is a very technical subject that can be quite difficult to understand, but in this article we want to tell you the story of hydraulics! We want to share with you who discovered hydraulics, what it was originally used for and how hydraulic power got to where it is today.
So why don’t we start at the beginning! Where does the word hydraulic come from?
The word hydraulic originates from the Greek word ‘Hydros’ which means water. Why water? Well, this is because water was the first liquid to be used in the hydraulic system. Today, hydraulics includes the physical behaviour of all liquids, not just water.
As we sympathise regularly with our readers, running hydraulic systems can be very costly. Not only can costs build rapidly from replacing damaged or worn components, but there is also system downtime to consider and to add to the expense.
If there is one deadly enemy for hydraulics, it’s contamination. In fact, contaminated fluids can be connected to more than 80% of all hydraulic failures. This includes all the related failures that can result including those of hoses, fittings, pumps and valves.
In fact, there is such a strong correlation between contamination of fluid and the lifespan of components that manufacturers of hydraulic and filtration products actually publish charts with the consequence predictions of not having inadequate filtration installed. Those systems that undergo rises in pressure will suffer from even more damage as contaminant particles make their way around the system.
Unfortunately the particles involved in hydraulic system contamination are usually far too small for the naked eye to see them. This is why it’s essential to use instruments specifically designed for contamination monitoring, otherwise a high system reliability cannot be expected to be maintained.
Although the operators and engineers who take care of industrial hydraulic systems are well aware of this problem, it’s only really coming to the fore of the mobile hydraulic system now. In this microcosm of the hydraulic world, there is still some time-based fluid maintenance going on. However, it’s becoming more apparent that this and spin-on filters are no longer enough to keep mobile hydraulic systems operating at their peak performance levels.
Quantifying contamination in hydraulic systems
Ideally every hydraulic system should have absolute filtration to capture both micro particles and those that are larger.
A Beta ratio of filtration will usually capture 99.5% of all particles that could contaminate a system. Alternatively the 1000 measurement will capture 99.9% of the particles. This will support the hydraulic system in enjoying a maximum service life. However, in addition to the Beta ratio, there are other considerations to ponder over when looking to keep the system clean.
How much dirt a filter can hold and how stable Beta ratio is will determine how well the filtration works out for the system. The best filters are usually cartridge-type that use a number of layers to help to maximise performance for all areas. Each layer will help the filter to either capture the dirt, hold it or to deliver the beta stability.
Another unexpected benefit of the cartridge-type filters is their ability to reduce how much loss of fluid there is when the filter is changed. This can keep go towards keeping costs down, whilst also lowering the impact on the environment. Although the cartridge type filter may cost more to buy, they deliver when it comes to protecting the system and cutting back on fluid loss.
With industrial hydraulic applications, cartridge filters are now considered to be the standard. They are also becoming more popular and widespread in the mobile market, which is becoming more sophisticated when it comes to components in addition to enduring rising costs.
Mobile Filtration Challenges and Solutions
Another area of concern with mobile hydraulic systems is that of space in the system to add filters and other components such as sampling valves. Quite often manufacturers will produce tank-top filters that can be integrated into the hydraulic reservoir, but sit out of the way. With global emission requirements becoming tighter, this trend is likely to accelerate in the coming years.
One issue that is unique to the mobile world is that of the cold start. It’s well known that any hydraulic fluid will thicken when sat at lower temperatures. This can increase the pressure drop for the filter element. The performance will take a downturn until the fluid begins to gain temperature and reaches the operating temperature level. Quite often the comment from an engineer will be ‘I started up and when I hit the level, nothing happened’.
Although it’s possible to install a large filter, it can add to the bulk and the cost of the system. Another work around is bypass the filter by adding in a pressure relief valve until the fluid is warmer. However, this can send contamination downstream. An approach that is less troublesome is to return the fluid to the reservoir as opposed to allowing it to circulate throughout the system.
In summary, as an engineer, the best move you can make is to identify and implement a fine filtration strategy that will enable your hydraulic system to run at its ultimate performance.
Hydraulic pumps, one of the more common mechanical applications of hydraulic technology, use fluid to push an arm a set distance forwards and backwards (or up and down). One example is the mechanical arms of a digger or other ground-working machinery. A hydraulic pump is perfect for this use, as the machinery works using the set distances between the components of the arms.
A hydraulic gear motor uses fluid to power movement for a much longer distance (or to put it another way, for an unspecified length of time). The motor works by running fluid through a chamber containing two cogs. One is linked to the drive shaft and transfers the power to the component that needs to move, and the other is idle, existing only to complete the mechanism. The same fluid is pumped through the motor chamber for as long as the power is needed, and it works in a similar fashion to an electric motor, but is much smaller and can be used in places where electricity is not safe or viable to use. It is a natural development of the waterwheel that was commonplace in the UK during the Industrial Revolution, powering cotton mills, woodworking and even bellows for blacksmiths forges.
A hydraulic gear motor is more appropriate than a pump for any piece of machinery that needs continuous power in a simple mechanism; a series of hydraulic pumps, arms and cogs can be used to create continuous power, but the resulting apparatus is bulky and made up of several components, which increases the likelihood of mechanical failure. A hydraulic motor, by comparison, can be very small and portable, meaning it is ideal for any application that is a long distance from traditional power sources and remote areas of the planet where other forms of energy are not viable. They are also reasonably simple in construction, so parts and maintenance are not an issue.
Hydraulic motors are ideal for use underwater and in dangerous places like mines and gas works, where the spark from an electric or petrol motor poses a serious fire risk. They are also good for any task where the motor is operated remotely, as the fluid can be pumped a long distance to the motor using comparatively little power and the only connection needed is piping, compared to more expensive electrical cable for running a remote electric motor. What is the most ingenious application of a hydraulic motor you have ever seen? Let us know in the comments below.
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.
How to read hydraulic circuits
Hydraulics symbols are an essential component of hydraulic circuit diagrams. Knowing some of the basic principles will help understand a wider range of symbols. Explaining the common ISO1219 symbols enables a complete hydraulic system to be followed:
1. Hydraulic Pump
Hydraulic pump produces flow. Oil is pumped from the hydraulic reservoir into the system. The basic symbol for a pump:
A fixed displacement pump is the simplest type and has a fixed output for each revolution of the input shaft. Modifications to this symbol describe the variable displacement pump. The types of control circuits show how the output is varied.
Filters clean oil entering the system, and are used in various places within a system. They protect hydraulic valves and pumps. Suction filters are placed at pump inlets to ensure only clean oil enters the system. Pressure filters can be placed throughout system. Return filters are common and filter oil returning to the reservoir.
3. Pressure Relief Valve
Pressure in a hydraulic system should be limited to control the force any motive devices produce and to ensure the safe/design limits are not exceeded. A pressure relief valve symbol is normally shown as:
A pressure relief valve or PRV passes fluid from an area of higher pressure to a lower pressure (typically the tank). Hydraulic pressure shown by the dotted line acts as a pilot to actuate the PRV by moving the arrow across the box. This happens when the pilot pressure produces an internal force equal to the spring load the valve begins to open and pass flow.
4. Check Valve
This valve is a one way valve that prevents flow in one direction. The addition of a spring ensures the valve will only open when this pressure is exceeded. Dotted pilot lines can be added so that pilot operating pressures can be used to open the valve and allow flow in the reverse direction. Commonly used to hold pressure in a hydraulic cylinder.
5. Hydraulic Reservoir (tank)
Hydraulic systems all have a means of storing hydraulic fluid. This is referred to as the hydraulic reservoir. Hydraulic reservoirs are shown as:
Vented hydraulic reservoirs are common place, but sealed systems can be found ion aerospace and marine applications. The return lines shown indicate the position above or below the oil level.
6. Directional Control Valve
Hydraulic fluid flow is controlled by a directional control valve. Commonly consists of four parts, valve body, spool, actuator, and springs. The spool is moved with respect to the valve body, this opens and closes internal flow galleries to control fluid flow. Various types of actuators provide power to shift the spool and springs are normally used to return the spool when the actuator is de-energised.
Look at the typical three position four way valve:
How to read directional control valve symbols:
a. Each box in the valve symbol represents a possible valve condition. In the three position valve above there are 3 possible conditions controlled by the actuators.
b. Number of ways tells you how many hydraulic connections could be connected to the valve.
c. Actuators always push and never pull the spool.
d. The box furthest away from the actuator is the normal or de-energized position, and is the position where the circuit connections are drawn. In the above valve this is the middle position.
7. Hydraulic Cylinder
Hydraulic cylinder or actuator uses hydraulic power to generate mechanical force. A hydraulic cylinder is shown as:
A double acting cylinder (above) has two ports and is therefore powered in and out. Single acting cylinders have one port and would typically be used for lifting applications.
We hope this gives you a useful introduction to hydraulic circuits. For a full list of hydraulic symbols can be found in ISO1219, or contact www.hydraproducts.co.uk for more help.
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