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Unless you’ve been involved with hydraulic systems for some time, it’s quite unlikely that you’ll be highly familiar with the ins and outs of the hydraulic manifold. Its purpose is to regulate the flow of fluid as it passes between actuators, pumps and other components in a hydraulic system.
Some engineers might compare the manifold to the switchboard of an electrical circuit as the flow of fluid is under the control of the operator. For example a hydraulic manifold of a backhoe loader will control whether the fluid is being diverted to the telescopic arms of the back bucket or the front bucket. The levers used by the operator in their cabin are connected to the manifold and it’s these that are used to control what the backhoe does.
A manifold works with a number of valves connected to each other. It is through the combinations of these valves that enable the manifold to control complex behaviour. The hydraulic valves are what control the flow of pressurized hydraulic fluid and direct it either to a cylinder or a hydraulic motor.
Manifolds are also known for many advantages including space reduction, pressure reduction, less connections and therefore less leaks. They also make it faster to assemble a hydraulic system as the components are consolidated into one unit. Some engineers feel wary of troubleshooting systems that have manifolds as there may not be an obvious place to start looking for issues. However, as long as the design of the hydraulic system includes test points, finding the root of problems can be much faster and easier. If transducers are attached, in the event of issues the data can then be displayed.
The applications where you’re most likely to find manifolds in use are in production equipment, material handling, heavy construction, food processing, oil field, off-highway equipment and machine tools.
There are two basic variations of the manifold… One is of the modular-block design which will support valves by providing interconnecting passages for just one or two valves with possibly some provision for flow-throughs. The other type is a mono-block design. This will support an entire system with valves and passages.
The material that manifolds are made from need to be strong and solid to handle the high pressure of the fluid. This is why they are manufactured in either laminar or drilled metal block. Most laminar manifolds will be created in steel with either milling or machining techniques used to pass through the layers of metal. Through the use of several layers that make up the passages, the manifolds are strong enough to take up to 10,000 psi.
Made in a bespoke custom manner, laminar manifolds are designed to suit the hydraulic system with passages added where needed.
When it comes to drilled metal block manifolds they can be manufactured from a number of different materials including steel, ductile iron and even aluminium. Blocks are drilled until there are flow passages, circuit paths and valves added where required.
In some cases there could be cartridge valves added to cavities in the surface of the manifold. Sometimes these are kept in place by plates and other times they are held in place by threaded bodies.
When it comes to selecting a hydraulic manifold to suit your hydraulic system setup there a number of different questions that you’ll need to answer. Keep in mind that there are software packages on the market that can be used to help the engineer design his or her perfect solution.
1. What type of fluid will you be expecting the manifold to handle?
2. Consider your seal materials – they will need to be able to connect the manifold to pipes and other components.
3. Which material and finish is going to suit your needs the most?
4. There are certain environmental conditions for every setup – keep these in mind including temperatures for your choice.
5. What pressure will the manifold be under when it’s under normal working conditions and maximum strain?
6. Check that the ports are suitable in size, location and type.
7. Are there enough valves on your manifold?
8. What flow conditions will there be – ie from a pump, an accumulator or a return?
9. What electrical voltage do you need and how will this be connected?
10. How will the manifold be mounted to the system?
This information should fill in any gaps in your knowledge about hydraulic manifolds. If you have any questions, feel free to drop us a line, we’ll do our best to help.
Hydraproducts manufactures micro hydraulic packs, the smallest of which is the unidirectional pack at 87mm square. These tiny hydraulic motors are often used in brakes and clamps, for mobility equipment such as powered wheelchairs and lifts, where space is at a premium but the power output still needs to be high enough to effect the actions required; up to 5 LPM.
Reversible micro packs are also available, although they are slightly larger, given that they must operate in two directions. Where the unidirectional packs use gravity to return back to their original position using solenoid and check valves, the reversible models use hydraulic flow to effect movement in both directions. These are often used in applications where tension is to be achieved across a component, or where fine positioning is very important, as the double direction movement can be tuned to exact position required. Common uses include mobility products such as lifts and wheelchairs; as well as bath lifts and other lifting equipment that needs to lower and rise within the same unit.
The reversible power packs are also available mounted to a cylinder for complete actuator manufacturing, and come with a selection of mounting plates for easy installation within whatever apparatus requires dual-direction hydraulic motion. These kits are also fitted with manual override function and have thermal relief valves, to release excess pressure from overloading or thermal expansion, which the solo units do not.
YouTube user maskinsmidjur has created, what seems to be, the world's smallest hydraulic bottle jack, which he claims is capable of lifting up to 1100 kg – a video he posted, shows him using the tiny jack to lift one side of his car. The jack itself is just over an inch tall and functions exactly as the standard sizes do. He made the jack himself and has other videos showing his miniature creations, which include a crossbow and bear trap. Unfortunately, the mini hydraulic jack is not available to buy, which is a real shame as it would make a perfect present for a hydraulic engineer or mechanic. Recreating this jack would take some real skill and dedication to make something this small, and perhaps this is the preserve of miniature model enthusiasts. It would certainly make a great addition to a scale model of an automotive workshop and would even come in handy for propping up loose hanging doors, as it would slide in easily underneath.
The smallest genuine hydraulic jack we could find is this bottle jack, from SGS Engineering. Capable of lifting up to 10 tons it operates at 700 bar with a 9.1 ton load, and lifts from 120mm to 149mm. The jack can be used vertically and horizontally and is a versatile little piece of equipment that would be very useful in many industries, as it is small enough to slide into very narrow gaps. There are models of hydraulic jacks available for remote control car enthusiasts, and they might make a good conversation piece in a workshop office, but many of these models actually use a spring mechanism to mimic the movement, rather than real hydraulic technology.
Building one of these tiny jacks would be a great project for getting would-be engineers into the world of hydraulics and understanding how they work, as well as the many applications of hydraulic technology and the equipment it is used in. With access to metalworking equipment, a very small hydraulic jack could be fabricated using the micro packs from Hydraproducts and some sheet metal, resulting in a very impressive science project for budding engineers or a nice conversational piece for hydraulically minded people.
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 .
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.
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.
Injuries are a relatively common occurrence for people working with hydraulics, especially those working in the maintenance and/or repair of hydraulic equipment. The most serious injury is a pressurised fluid injection, but accidents can also happen with moving parts when the stored energy in the system is not released before inspections and repairs are made. Unfortunately, it is not routine for tags and gauges to be used to denote places where energy is stored. The engineer must study the schematic thoroughly before starting any investigative work, in order to be sure that there is no danger of anything moving while they are working on the machinery.
If pressure gauges were used to show the residual pressure left in moving parts the engineer could utilise the pressure relief valve to release the stored energy and make the hydraulic equipment safe to work on. Relieving pressure stops anything moving of its own accord, which could be dangerous, and also reduces the risk of high pressure hydraulic fluid injection injuries, which can be fatal.
When inspecting for leaks in seals and hoses, it is important that pressure is released before checking but even then, it is not advisable to check with your hands. Instead, perform a visual inspection and look for other signs of leaks, such as fluid on the floor or on parts of machinery that sit underneath the suspected location of the leak.
Hydraulic equipment can be just as dangerous as electrical circuits for those investigating and repairing faults; but electrical work is governed by strict regulations which include the use of lockout tags and labels denoting the location of potentially dangerous components. Hydraulic equipment is not covered by such stringent regulations and as such, it is at the discretion of the designer whether pressure gauges and safety accessories are included in the machinery at the time of building. These items can be retrofitted by the owner, but this is not often done and this means hydraulic engineers must spend a lot of time reading manuals and schematics to understand where the dangers lurk, before being able to safely get on with any repair work.
Just because it isn't legally required, there are no good arguments for overlooking these safety precautions, but several reasons why they should be addressed., such as: reduced downtime on repair and maintenance tasks, a reduction in the potential for workplace injuries and a speedier repair. All effected by removing the need to spend time studying diagrams to pinpoint potential dangers. Employee health and safety is of paramount importance to employers, and this could well be the biggest reason why hydraulic equipment should be fitted with pressure gauges, relief valves and lockout tags, to prevent tampering with settings and to alert engineers to the locations to address first.
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