Get in touch today to discuss your requirements
Call: (+44) 01452 523352
There’s no doubt that having an accurate diagram of your hydraulic system setup can save many an engineer considerable time and trouble. Here are the main diagrams that you might want drawn up of your system to refer to when needed:
Block Diagrams using blocks joined by lines, this diagram illustrates how the components are installed in addition to their connections and interactions.
Cutaway Diagrams illustrate what’s inside of hydraulic components including flow paths. Colours, patterns and shades are used to represent flow paths and pressure.
Pictorial Diagrams present the arrangement of the components and pipes of the hydraulic circuit. Usually this diagram shows the shapes and sizes scaled to help with component identification and recognition.
Graphical Diagrams simple symbols are used to represent each hydraulic component, their connections and controls.
Hydraulic technicians who have experience at interpreting circuit diagrams find these a great resource for understanding what could be at the core of any problem for troubleshooting purposes.
Without the schematic diagram, the hydraulic engineer must work hard to comprehend the design of the circuit and use isolation to identify potential origins of issues. At best, this can take a lot of time and energy that needn’t be spent.
In worst case scenarios, a valve manifold may need to be dismantled and removed in order to understand what its purpose is. Without a full understanding of any component in a hydraulic system it’s difficult to know exactly what is causing an issue. The purpose of the schematic diagram is to remove the necessity to reverse engineer the hydraulic circuit.
Do you use hydraulic circuit diagrams to support maintenance and repair in your business? If so, which types do you use to enable your engineers to gain a fast and complete understanding of your systems?
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.
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 .
The reliable operation and output of a hydraulic system is dependent on how efficient and well maintained it is. If conditions are not optimal, the driving motor will be under pressure in a struggle to overcome loss of power. This is because details, such as right down to the viscosity of fluid, are important. If it’s not right, it can result in a sluggish system.
A sluggish system can affect how much control there is and how the performance of the output is, as the response of the motor will be poor. Also, you can expect it to run in a more costly fashion as more fuel will need to be burnt in order to maintain its performance if it’s a combustion engine.
The efficiency of these types of systems are reliant on both mechanical and volumetric efficiency. Frictional loss can impact mechanical efficiency as it will struggle to compensate. The conditions in which a frictional loss are likely to occur is when the metal surfaces are rubbing together. This could be a result of there not being enough oil to keep the system lubricated. Under normal operating conditions, there would be enough fluid to keep all components of the hydraulic system lubricated.
Hydraulic systems are not very flexible in some ways. They are made for hydraulic fluid to be flowing at an optimal level. Hydraulic specialists will encourage engineers to keep their systems running within a range of specifications and limitations to get the best of their machinery. When the system is tuned and working to deliver a good performance, not only does the efficiency increase but the system is likely to be far longer lasting and durable.
One of the methods that engineers use to maintain a hydraulic system is to run the temperature of the system at the same level throughout the entire operating cycle. In order to do this, it’s important to watch out for a number of factors such as how much air and water may be getting into the system.
Once they are operating at their maximum output with a balanced system, hydraulic machinery can produce great output.
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.
Investment in business and design software has been a pivotal part of Hydraproducts growth over the last 10 years.
Upgrading our complete design suite to include Visio HyDraw600 has been our latest investment. Hydraulic circuit design forms an important part of communicating with our customers. HyDraw offers far more than that, Hydraulic manifold design and validation features mean our designers can quickly convert Hydraulic circuits into manufacturing instructions for direct application to CNC machining centres.
Accurate Hydraulic circuits using the latest ISO 1291-1 symbols can be selected from a comprehensive library of symbols, valve model data and manufacturers databases.
Simple drag and drop features allow complex hydraulic systems to be quickly displayed. Symbols have intelligent data linking to Hydraproducts valve and component databases, allowing our engineers to auto generate bill of materials. Symbols can be linked together using the “snapping” functions. Smart jumpers, connectors and snap to connection points make this an easy process. Connections are easily maintained when moving symbols around and kinks are removed to straighten connections.
Engineering features such as pressure capacity, maximum flow rate and pressure drops are displayed during the selection process ensuring all of our designs meet our customer needs.
Seamless integration into our SOLIDWORKS software is an exciting feature allows hydraulic manifolds to be converted into CAD files and 3D models.
HydrawV600 has reduced our hydraulic design time to 50% enabling Hydraproducts to firstly communicate and develop hydraulic power unit designs more effectively with our customers but secondly bring these designs to reality to our workshops in less time.
Thanks to VEST HyDraw 600 we are more clearly communicating the technical features of our hydraulic power packs internally and externally, bringing our business some real benefits.
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 Power Pack
Connect with us
Connect with us on social media or eBay