Principles of Oil Hydraulics

What are the basic components of oil hydraulic system, how do these components work together to support industrial applications, and how can we keep them working safely and efficiently? This website serves to answer these questions.

oil hydraulic pump

Oil Hydraulic System Basics

Here are some components of a basic hydraulic system: We have the pump, relief valve, directional control valves, and cylinder cap. This has been mentioned before. The relief valve and pump are next to the reservoir. We are now changing the direction of the valves, pushing oil into the rod end to retract the cylinder. And over here, we are injecting oil into the rod end to extend the cylinder. The rod-end oil is then returned to the tank. Click here. The reservoir is also refilled with oil from the cap. This is an animated drawing, considering our small setup.

Cylinder Expansion

The cylinder will expand in less than a minute. Why? We only have a 100-liter pump per minute and a 100-liter cylinder in this region. A 100-liter-per-hour pump and 100 liters of water are also required. The cylinder will expand in a minute. We assume a ratio of two to one area. 50 liters of rod volume is equal to 50 liters. The cylinder expands in one minute, and it pumps out 50 liters every minute. The rod tip's flow rate is, therefore, 50 liters per minute. We will therefore have 100 liters of oil when we switch on the directional control valve, and we can pump oil into the rod tip. This activity has a two-to-one area ratio. We will then withdraw in thirty seconds. Then, in less than 30 seconds, we will expend 100 liters of oil.

Oil Flow Rate

However, the flow rate is always expressed in liters per minute. This means that the flow rate is 200 liters per minute. People have tried to ask me why I produce oil. I hope they could. This is how we continue to do it. We pump in 100 liters per minute. The chamber holds 100 liters. The hydraulic cylinder retracts in about a minute, and we expend 100 liters in less than a minute. However, the flow rate is 200 liters per hour. The cylinder's faster retraction speed causes the return flow rate to increase. That's it for this little system. Here's the sketch. The circuit will also be covered. Oil is coming in from the south. The oil flows through the directional valve to the cylinder. Rod-end oil returns to the tank. We must choose pipe diameters and valve sizes in a hydraulic system. Be careful. Once we have reached this point, switch the valve, and the cylinder will retract faster. Assuming that the cylinder is producing 200 liters of fluid per minute, the pipe out here must be capable of holding 200 liters.

Oil Directional Valves

The directional valve must also be capable of handling 200 L/min. A return line filter will be installed to handle 200 liters per hour. Our pressure-line filtration would also be 100 liters per minute. Depending on the size of the piston, the cylinder will retract faster. Our ratio would be 2 to 1. This concludes our story. This will allow you to interpret the sign and see the cylinder expand or retract every time. It shows our four-stroke, three-directional control valve. It is controlled by a solenoid. These are the solenoids. This sign is spring-centered. It will lengthen the cylinder when the "A" solenoid activates. When the "a" solenoid is activated, the symbol will cause the cylinder to move in the direction of the sign. OK. Now we can activate the solenoid. We now activate the solenoid. The middle envelope is gone, P to A, the cylinder extends, and rod oil returns to the tank. Now that the valve has been lowered to neutral, we are hydraulically locked against all closed ports. The right-hand solenoid has been energized. We retract the cylinder, and then the middle solenoid disappears. Then, the hydraulic lock is restored.

Components of an Oil Hydraulic Circuit

Here's a quick look at the components of a hydraulic system. It is simple to arrange, with the electric motor and pump at the bottom, followed by the relief valve. This is the relief valve for pilots. The power triangle shows that there is a spring inside the spring. Next, we have the pressure line filter, which is located over there. Then, our four-stroke, three-port, three-position directional control valve It houses both the A envelope and the B envelope. The ones in the middle are a zero envelope and a solenoid. The little diagonal lines indicate coil winding. We have a cylinder, return, and filter lines.

Oil Hydraulic Circuit Design

This gives us an understanding of the fundamentals of how circuits are built together. A fundamental elementary circuit, perhaps? Another interesting one is the determination of pipe dimensions. To determine the diameter of a pipe, the formula is simple. To determine the velocity of the fluid within the pipeline, multiply Q by twenty-one point two and then divide V by V. Once you have the answer, click the square root button to calculate the diameter. The diameter will now be displayed in millimeters. Q will then be shown in liters per hour, and V will show the fluid velocity in meters per second. Below is a slide that will show you how to determine the twenty-one comma (2/2), or the twenty-one point (2/2). Let's take a closer look. What is the formula for determining the pipe size? A is Q multiplied by V. Q is in meters per minute, and V is the distance in meters per second. The answer will be in square meters, evidently.

Hydraulic Oil Pipe Sizing

You cannot buy pipe in square meters. A pipe cannot be purchased in square meters. It must be measured in millimeters. To get the answer, divide the result by velocity in meters per second. If we have more divisions than we can divide, we must flip it. Then we have meters divided per second, followed closely by seconds over meters. We can nullify; we have nullified, and then we get meters squared. The solution is meters squared. We cannot buy plumbing in square meters, as we have already stated. Let's now look at our formula. The area is Q multiplied by V. This will convert the flow rate to liters. We then divide 60 by 60 to convert liters per minute to liters per second. This information is then entered into the calculation, and it equals the area. We take the area and add it to the calculation. We then multiply the area by four. Multiplying one thousand by four yields four thousand divided by sixty, and then PI. Here are the twenty-one commas: 2 2 0 7. We will add a few numbers to the list. We follow the 21-comma, 2-word rule. We multiply the flow rate by twenty-one points two, then divide by - on the suction line and 3 m/s on the pressure line.

Loses in Oil Hydraulic Systems

To ensure there is not a big loss of oil, it is very important to select a pipe with the right diameter. If there are losses, this would mean that we have to spend money to push the oil down the pipes. This demonstration gives us an idea. The process would be identical if we had a glass tube. We could just run water through it. It happens down below, where there is no pressure. As we reverse the process, however, the pressure increases due to the resistance and friction of the pipe. This increase in pressure can be converted into mechanical leverage for industrial applications. This is a very unique arrangement.

Energy Conservation

We'll show you what's happening now that we have reached the topic of energy conservation. We have a venturi in the middle. Fluid is flowing through the hydrostatic drive. When we have higher velocities, there is a pressure drop in the pipeline. This means that we have high pressure here and high velocity there, as well as a pressure reduction. This line is slightly lower because of the length of the pipe. We are only showing this section of the venturi. The text now reads: "As the fluid accelerates through the venturi, pressure decreases." The text concludes that the pressure rises as the fluid velocity slows with increasing dimension. Let's now take a look at the second.

Increasing Pressure

The velocity drops and the pressure goes up because we have the same-diameter pipe inside the outlet. The pressure has risen here. Although it is a very small amount, it is enough to show that energy cannot just be transformed but not destroyed. Let's now look at another example. This section will discuss Pascal's law and give an example. The force is on top, the liquid is inside, and arrows are pointing everywhere. Pascal's law states that pressure applied to a confined liquid transmits without diminution in all directions. It acts with equal force in all areas and at right angles.

Pascal's Law

Pascal's law governs hydraulics in general. This is a history lesson. Blaise Pascal was exactly who? He lived between 1623 and 1662. He died at 39 years old. He was a mathematician. Amazingly, he graduated college at the age of 16. His last five years were spent researching hydraulics. We use Pascal instead of Newtons per square meter to express pressure. Let's now move on to the next minor issue. We just talked about Pascoe's law, but I wanted to briefly review it. This means that when pressure is applied to a fluid, it acts in the same way in all areas. Pascal's law applies to hydraulics in all aspects. Pressure is present throughout the entire system and not at any one location. We now have an illustration of Pascal’s law. Once again, the cylinder is sent out, and we have right-angled arrows leading to its rear. Our resistance causes us to feel pressure. Pressure is created by the resistance of the load. This note shows how pressure can be applied in all directions. Let's do it again. We've done it. We see arrows coming in every direction, at either 90° or right angles. Then, resistance occurs, and we can see high pressure on our pressure gauge. Fluid is being compressed into the cylinder, which is something that we should always remember when dealing with hydraulic pressures.

Compressibility of Hydraulic Fluids

Some people believe liquids can't be compressed. However, this is incorrect. High pressures can cause problems with fluid compressibility. This article gives us an idea. The fluid's compressibility is approximately one percent per 14 megapascals (MPa) for oil and about one percent per 21 MPa for water.

Bulk Modulus of Water

Water has a slightly higher bulk modulus than oil. One would need to add a liter more oil to raise the pressure to 14 MPa. This is based on the cylinder being 100 liters full. This is why we have drawn a miniature hydraulic cylinder. The cylinder contains 100 liters of fluid when fully expanded. We added another liter of oil to achieve this pressure. If the pressure was, for instance, 28 MPa, the cylinder would have about two liters of oil. If we have a press that is bringing down high pressure and we add an extra liter of oil to the cylinder, and then if the solenoid valve is changed to retract the piston at the speed of a moving solenoid, we will experience a huge shock in the hydraulic system. This could cause cracking and possibly lead to pipes leaking.

System Decompression

The system must first be decompressed. After that, the cylinder can be pulled back. This may take only seconds. This will not only reduce production but also prevent the hydraulic system from being stressed. The hydraulic system should not be subjected to shock. Another example. This is another example. The sand and rock decompress naturally when loaded into the truck. We must be careful, just like with the media. Decompression is essential, as we have already mentioned. This is an example of hydraulic pressure that is caused by resistance to the pump's flow rate and not the pump itself. Many people cite the hydraulic pump as the source of pressure in their hydraulic system. This is incorrect, as pressure is generated by the load's resistance. There have been instances when a very expensive pump was forced to be replaced due to a sudden loss of pressure. There is still no pressure, even after installing a brand-new pump.

Damaged Hydraulic Seals

Further inspection revealed that the seals on the hydraulic cylinder were damaged. A broken spring and relief valve were also found. It is difficult to blame the pump if there is no pressure. Pumps provide oil, and pressure is created by the resistance of the load placed on the cylinder. Let's take a look at the animation. We send our cylinder. Naturally, there is no pressure. The pressure gauge now reads zero. Now that resistance exists, pressure starts to rise and can be seen on the pressure gauge. The pressure rises only when the cylinder meets resistance, as shown in the previous illustration. Another idea is the image at the bottom of this page.

Oil Reservoir

We may imagine passing through this area, which contains a reservoir. This pump is receiving the oil. Let's pretend these little triangles are needle valves. When we turn the needle valve in, there is no flow resistance. Thus, no pressure exists. But if resistance is applied, pressure increases. We are now. Let's do it again. We install our needle valve and add resistance to the line. The pressure has increased. To release the excess pressure, we will need a relief valve if we increase our pressure. This gives a glimpse of what's happening here.