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A design decision to fit a hydraulic oil cooler like this can only be made with a full assessment of how much heat is going to be put into the oil and how much of that heat can the system dissipate without the oil overheating.
The heat comes from inefficiencies or losses. The greater the inefficiencies the greater more power input will be required to overcome them. The inefficiencies will manifest themselves as heat. So the amount of extra input power required can be assessed as:-
Input Power due to inefficiencies = Power Loss (pump) + Power Loss (valves) + Power loss (pipework)+….
This is often described as “heat Load” and if this is greater than the system heat dissipation the system will overheat without a hydraulic cooler.
Where does the heat come from?
The most common cause of heat is pressure drop, this being a decrease in pressure across a device as the oil flows through it.
Sizing of control valves and pipework is critical to reducing heat sources, for example a Cetop03 Directional Valve that is rated at 80lpm with 50lpm of flow from the A to T ports may have a pressure drop of 10 bar would generate (10*50/550) 0.9kW of heat.
Selection of high efficiency pumps and motors is also important, for example a Gear pump that is driven by a 11kW motor would typically have an efficiency between 90 and 95%. This will mean that the output power of the pump will only be 10 to 10.5kW, so 0.5 to 1kW will be heat.
From the initial design of the whole system it is possible to make an estimation of the total heat load. The heat load of an existing system can simply be estimated by measuring the oil temperature rise over time.
Will my powerpack dissipate enough heat without a hydraulic cooler?
Typically the oil reservoir will be sized with heat dissipation in mind. Lets not forget that a system that operates for 1 minute every hour will put a lot less heat into the oil and has much longer to dissipate that heat.
Tank heat loss can be expressed as :- kW= DT * A * 0.016
DT = temperatute difference between oil and ambient (oC)
A = Surface area of tank, generally excluding base (m2)
For example a 55Litre tank could have a surface are of 1m2 and if there is an ambient temperature of 20oC, and the oil temperature is 60oC, then the tank will dissipate 0.7kW.
The maximum oil temperature allowable will depend a little on the type of components and oil used, but in general temperatures above 80oC will damage most seals and degrade performance of many commonly used hydraulic oils.
All of the system will dissipate heat, pipes, fittings and valve bodies etc. So for a full system heat loss figure the total surface area of the system could be considered. In systems where pipework and hydraulic cylinders are large this surface area could be worth consideration.
If the system heat loss is less than the heat load then, yes the hydraulic system will require hydraulic oil coolers if it is to be 100% duty rated.
Keep cool and improve the design
Sources of heat can be designed out of systems by careful selection of the correct valves and by setting them appropriately.
Some of the simple design errors to avoid:-
• Ensure the pump is not operating at full pressure while it is not in use. This will cause the system relief valve to by-pass to tank at full pressure drop. This will cause a heat input equal to the full input power. It is always recommended to use an loading valve so the pump by-passes to tank at the lowest possible pressure drop.
• Slowing cylinder or motors down using a throttle or flow control valve. If a system has a fixed displacement pump then the use of a flow restriction like this cause the pump pressure to increase to the pressure setting of the system relief valve. So the cylinder or motor is only slowed because some of the pump output is by-passing to the tank via the pressure relief valve. Correct pump selection is vital if this situation occurs.
• Load control valves such as overcentre or counterbalance valves that are set too high will cause the system to require excessive pressure when lowering. The pump will have to work harder than necessary.
• Pipework sizing, can be misunderstood, particularly when long hoses are used. For example a 30metre long 3/8” hose with 50lpm flow will have a 15bar pressure drop.
If your system is to run continuously then firstly ensure that system design is optimised and then consider the heat load. A mixture of system heat dissipation and the use of hydraulic coolers will always ensure your powerpack doesn’t overheat.
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 .
As designers and manufacturers of the highest quality hydraulic parts we are very proud of our mini hydraulic power packs, which can be driven from 12 or 24-volt direct current (DC) supplies. Our OEM customers rely on our consistency and quality to build functional and reliable equipment, including tail lifts, tipper trucks and trailers. Typically, our 3kW output motor, which relies on a 24v DC supply, is used to raise and lower the ramps of trailers used to transport heavy equipment. The nature of the equipment using the ramp, means that the ramp itself must be sturdy in construction and therefore, quite heavy to lift. The 3kW mini power pack does this with ease, and is fan cooled to guard against overheating.
For more lightweight applications, such as tailgate lifts on commercial passenger vehicles, a smaller output is needed. For these uses a 12v mini hydraulic power pack is used, as the 12v motor can be wired into standard vehicle electrical circuits for tailgate lift functions. The 12v model is available with a 500W or 800W output, so the choice depends on the amount of power that is needed to drive the hydraulic pump in the system.
We manufacture our products to be compatible with all major brands of pumps and valves, so they can be used in any system where a new component is needed, or the system needs to be upgraded to handle a larger capacity. Our valves and other components we manufacture, are also designed to be used in a wide variety of systems, and with a global distribution network we can serve your DC hydraulic motor needs wherever you are.
Our mini hydraulic power packs may be small (around 16 inches long) but they are capable of packing a mighty punch; the model with most capacity is the 3kW, 24v model, but the 12v and 24v models have outputs between 0.5kW and 2kW. This is a wide range of strengths, allowing our customers to use the most efficient and appropriate motor for their needs. This range also means systems can be designed with the lowest possible power consumption across all parts, but with the most efficient hydraulic output of that power. System designers do not have to compromise on power because the ideal output size is not available. We do make bespoke components, so even if we don't have the exact off-the-shelf DC power pack you need, we can still make it happen for you.
Our micro hydraulic power packs are also a great option for when one of our mini power packs are too large for the space available. They are only 89mm square and can be discreetly installed in the moving arm of a security barrier or automatic gate system. The 0.5kW mini motor with 12v DC supply is often used for step lifts and other applications where the load to be moved is not too heavy, so step lifts and passenger lifts on small vans or taxis that will not be taking huge equipment, can be driven by one of these smaller motors. Running on a 12v DC supply means that the tail lift system can be seamlessly integrated into the electrical systems of the vehicle, and operated from the standard dashboard. The driver can raise or lower the lift from the comfort of the driver’s seat and not worry about having to use separate controls for this action.
If you are reading this as an OEM then please do not hesitate to get in touch with us. If we haven't got your ideal component listed on our website, then we will be delighted to create a bespoke product that answers your problems, all manufactured on site in the UK. Call us today on 01452 523352
There have been many comparisons between hydraulics and pneumatics in the past with each having their own benefits.
As you are aware we love hydraulic power, we wouldn’t do what we do if we didn’t. But, today we wanted to write an article on some of our favourite machines that are powered by hydraulic powerpacks. We have told you before that the world is a better place because of hydraulic powerpacks, and today we are going to prove it.
Firstly we have chosen to look at how hydraulic powerpacks help the everyday mechanic.
In the UK, there are as many as 36 million cars registered on the roads. At many points during a cars life, they will need to visit a garage. Hydraulic lifts are vital for mechanics to see and get under your car and our hydraulic powerpacks can easily connect to your mechanics lift, providing all the power it needs to lift up your car. This in turn not only makes a mechanics job much easier, but it also means your car has been thoroughly checked over. Thanks to hydraulic power your car will spend a minimal amount of time out of action.
Hydraulic power packs, such as the ones supplied by Hydraproducts, are a vital part of the construction industry. With a huge push on new home building across the country, it is a daily occurrence to see heavy plant equipment moving earth and preparing groundworks for construction. All of these ‘earth moving’ machines use hydraulic power to effect motion in the moving parts, with hydraulic rams serving as the muscles of the machine to raise and lower a digging arm, or to move large pipes into place for infrastructure development.
Hydraulic power packs allow the machinery to generate more power in the moving parts than if just the engine power alone was directly driving the hydraulics, so they mean a smaller excavator can move as much as a larger one without the need for that extra space. On new build sites, there is a lot of space to start with, so there is no issue with the largest machinery manoeuvring around the site. When houses start to go up and roads are installed, there is less machinery space and it makes sense to use a smaller version of a particular machine that has the same power capabilities.
A hydraulic power pack can also reduce the amount of fuel used to drive the hydraulic components, as most heavy earth moving equipment has a range of modes that can be selected to give the right amount of power while remaining economical. Digging out large amounts of earth will use a lot of power, and this can be increased above the machinery capacity by using a hydraulic power pack. Fine grading of embankments, or excavating over mains power, gas or sewage pipes requires a fine degree of control that is best achieved at a lower power. Hydraulic power packs can help to control this when used in combination with the modes available on the machinery itself. The effect is a reduction in fuel used to generate the hydraulic power and a considerable cost saving over the lifespan of a project.
Because the earth moving equipment uses hydraulics there is no need to employ a separate engineer to maintain and repair the hydraulic power packs as they use the same technology, so there is no extra cost in maintenance terms, just the cost of the power pack. When considering this investment, it is important to understand that the better control leads to improved productivity and workforce morale, as well as a lower outlay on fuel.
Hydraulic power packs are not confined to use in the preparatory stages of a large building project, however, they are also used to work cranes, that lift roof struts into place; in forklifts, that move materials around the site and even in concrete pumping machines, that are used to lay floors and external hard standing surfaces. Hydraproducts are very happy to work with equipment manufacturers to find or design the perfect hydraulic power pack for the construction industry.
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.
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