Hydraulic system: calculation, scheme, device. Types of hydraulic systems. Repairs. Hydraulic and pneumatic systems

The hydraulic system is a device designed to convert a small force into a significant one, using some kind of fluid to transfer energy. There are many types of nodes functioning according to this principle. The popularity of systems of this type is due primarily to the high efficiency of their work, the reliability and relative simplicity of the design.

Scope of use

A wide application of this type of system was found:

  1. In industry. Very often, hydraulics is an element of the design of metal-cutting machines, equipment designed to transport products, to load / unload them, and so on.
  2. In the aerospace industry. Similar systems are used in various kinds of controls and chassis.
  3. In agriculture. It is through hydraulics that the hinged equipment of tractors and bulldozers is usually controlled.
  4. In the field of cargo transportation. In cars, a hydraulic braking system is often installed.
  5. In ship equipment. Hydraulics in this case is used in steering, is part of the design scheme of turbines.

Operating principle

Any hydraulic system operates on the principle of a conventional liquid lever. Supplied inside the assembly, the working fluid (in most cases, oil) creates the same pressure at all its points. This means that, with a small effort on a small area, you can withstand a significant load on a large.

Next, consider the principle of the operation of such a device using the example of such a unit as the hydraulic brake system of a car. The design of the latter is quite simple. Its scheme includes several cylinders (main brake, filled with liquid, and auxiliary). All these elements are connected to each other by tubes. When the driver presses the pedal, the piston in the master cylinder starts to move. As a result, the liquid begins to move through the tubes and gets into the auxiliary cylinders located next to the wheels. After that, braking is triggered.

Arrangement of industrial systems

Hydraulic brake of the car - the design, as you can see, is quite simple. In industrial machines and mechanisms, liquid devices are more complicated. The design they have may be different (depending on the scope of application). However, the schematic diagram of the hydraulic system of an industrial sample is always the same. It usually includes the following elements:

  1. A liquid tank with a neck and a fan.
  2. Coarse filter. This element is designed to remove from the incoming fluid into the system of various kinds of mechanical impurities.
  3. Pump.
  4. Control system.
  5. The working cylinder.
  6. Two fine filters (on the supply and return lines).
  7. Distribution valve. This element of the structure is designed to direct the liquid to the cylinder or back to the tank.
  8. Reverse and safety valves.

The operation of the hydraulic system of industrial equipment is also based on the principle of a liquid lever. Under the influence of gravity oil in such a system gets into the pump. Then it goes to the control valve, and then to the piston of the cylinder, creating pressure. The pump in such systems is not designed to absorb liquid, but only to move its volume. That is, the pressure is not created as a result of its work, but under the load from the piston. Below is a schematic diagram of the hydraulic system.

Advantages and disadvantages of hydraulic systems

The merits of the nodes working on this principle include:

  • The ability to move loads of large dimensions and weight with maximum accuracy.
  • Practically unlimited range of speeds.
  • Smoothness of work.
  • Reliability and long service life. All components of such equipment can be easily protected against overload by installing simple pressure relief valves.
  • Economical operation and small size.

In addition to the advantages, there are hydraulic industrial systems, of course, and certain drawbacks. These include:

  • Increased risk of fire during operation. Most liquids used in hydraulic systems are flammable.
  • Sensitivity of equipment to contamination.
  • The possibility of oil leaks, and therefore the need to eliminate them.

Hydraulic system calculation

When designing such devices, many different factors are taken into account. These include, for example, the kinematic coefficient of viscosity of the liquid, its density, the length of the pipelines, the diameters of the rods, and so on.

The main purposes of performing calculations of such a device as a hydraulic system are most often the definition:

  • Characteristics of the pump.
  • Values of the stroke of the rods.
  • Working pressure.
  • Hydraulic characteristics of highways, other elements and the whole system.

The hydraulic system is calculated using various kinds of arithmetic formulas. For example, pressure losses in pipelines are defined as follows:

  1. The estimated length of the mains is divided by their diameter.
  2. The product of the density of the liquid used and the square of the average flow velocity are divided into two.
  3. Multiply the values obtained.
  4. Multiply the result by the path loss factor.

The formula itself looks like this:

  • Δp i = λ x l i (p): d x pV 2 : 2.

In general, in this case the calculation of losses in the mains is carried out approximately on the same principle as in simple structures such as hydraulic heating systems. To determine the characteristics of the pump, the magnitude of the stroke of the piston, etc., other formulas are used.

Types of hydraulic systems

All such devices are divided into two main groups: open and closed type. The schematic diagram of the hydraulic system considered above relates to the first variety. Open devices are usually devices of low and medium power. In more complex systems of a closed type, a hydraulic motor is used instead of a cylinder. The liquid enters it from the pump, and then returns to the pipeline again.

How to repair

As the hydraulic system in machines and mechanisms plays an important role, its service is often trusted by highly qualified specialists engaged in this particular type of company activity. Such firms usually provide a full range of services related to the repair of special equipment and hydraulics.

Of course, in the arsenal of these companies there is all equipment necessary for the production of such works. Repair of hydraulic systems is usually performed on site. Before it is carried out, in most cases, various kinds of diagnostic measures should be performed. To this end, companies engaged in servicing hydraulics use special facilities. The staff members of such firms are also usually brought with them to eliminate the problems.

Pneumatic systems

In addition to hydraulic, pneumatic devices can be used to drive units of various kinds. They work roughly the same way. However, in this case, the mechanical energy is converted into compressed air, not water. And hydraulic, and pneumatic systems quite effectively cope with their task.

The advantage of devices of the second type is, first of all, the lack of the need to return the working fluid back to the compressor. The advantage of the same hydraulic systems in comparison with pneumatic systems is that the environment in them does not overheat and is not supercooled, and therefore, no additional nodes and parts need be included in the circuit.

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