A hydraulic system is a device designed to convert a small force into a significant force using any fluid to transfer energy. There are many kinds 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
Widespread use of this type of system found:
- In industry. Very often, hydraulics are an element of the construction of metal-cutting machines, equipment intended for the transportation of products, their loading / unloading, etc.
- In the aerospace industry. Similar systems are used in various controls and chassis.
- In agriculture. It is through hydraulics that the attachments of tractors and bulldozers are usually controlled.
- In the field of cargo transportation. In cars, a hydraulic brake system is often installed .
- In ship equipment. Hydraulics in this case is used in steering, is included in the design of turbines.
Operating principle
Any hydraulic system works on the principle of a conventional fluid lever. The working medium supplied into such a unit (in most cases, oil) creates the same pressure at all points. This means that by applying a small force on a small area, you can withstand a significant load on a large one.
Next, we consider the principle of operation of such a device on the example of such a unit as a hydraulic brake system of a car. The design of the latter is quite simple. Its scheme includes several cylinders (brake master, filled with fluid, and auxiliary). All these elements are connected to each other by tubes. When the driver presses the pedal, the piston in the master cylinder moves. As a result, the liquid begins to move through the tubes and enters the auxiliary cylinders located near the wheels. After that, braking is triggered.
The device of industrial systems
The hydraulic brake of the car - the design, as you see, is quite simple. Industrial machines and mechanisms use more fluid devices. Their design may be different (depending on the scope). However, the schematic diagram of the hydraulic system of an industrial design is always the same. Usually it includes the following elements:
- Liquid tank with neck and fan.
- Coarse filter. This element is designed to remove various kinds of mechanical impurities from the fluid entering the system.
- Pump.
- Control system.
- Slave cylinder.
- Two fine filters (on the supply and return lines).
- Control valve This structural element is designed to direct fluid to the cylinder or back into the tank.
- Check and safety valves.
The hydraulic system of industrial equipment is also based on the principle of fluid lever. Under the influence of gravity, the oil in such a system enters 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 intended to absorb liquid, but only to move its volume. That is, pressure is created not as a result of its operation, but under load from the piston. Below is a schematic diagram of a hydraulic system.
Advantages and disadvantages of hydraulic systems
The advantages of nodes working on this principle include:
- The ability to move cargo of large dimensions and weight with maximum accuracy.
- Virtually unlimited speed range.
- Smoothness of work.
- Reliability and long service life. All components of such equipment can be easily protected from overload by installing simple pressure relief valves.
- Profitability in work and small sizes.
In addition to the advantages, hydraulic industrial systems have, of course, certain disadvantages. These include:
- Increased risk of fire during operation. Most fluids used in hydraulic systems are flammable.
- Sensitivity of equipment to pollution.
- The possibility of oil leaks, and therefore the need to eliminate them.
Calculation of the hydraulic system
When designing such devices, many different factors are taken into account. These include, for example, the kinematic coefficient of viscosity of a liquid, its density, length of pipelines, rod diameters, etc.
The main goals of calculating a device such as a hydraulic system are most often to determine:
- Pump specifications.
- Values โโof 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:
- The estimated length of the lines is divided by their diameter.
- The product of the density of the fluid used and the square of the average flow rate are divided into two.
- Multiply the obtained values.
- Multiply the result by the travel loss coefficient.
The formula itself looks like this:
- โp i = ฮป x l i (p): d x pV 2 : 2.
In general, in this case, the calculation of losses in highways is carried out approximately according to the same principle as in such simple structures as hydraulic heating systems. Other formulas are used to determine pump performance, stroke, etc.
Types of hydraulic systems
All such devices are divided into two main groups: open and closed type. The principle diagram of the hydraulic system considered by us refers to the first variety. The open design is usually of low and medium power devices. In more complex closed-type systems, a hydraulic motor is used instead of a cylinder. The fluid enters it from the pump, and then returns to the line again.
How is repair done
Since the hydraulic system plays a significant role in machines and mechanisms, its maintenance is often entrusted to highly qualified specialists engaged in this particular type of activity of companies. 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 everything necessary for the production of such work equipment. Repair of hydraulic systems is usually done on site. Before carrying out this, in most cases, various kinds of diagnostic measures should be performed. For this, companies involved in the maintenance of hydraulics use special installations. The necessary components to resolve the problems of such companies are also usually brought with them.
Pneumatic systems
In addition to hydraulic, pneumatic devices can be used to drive the nodes of various mechanisms. They work approximately on the same principle. However, in this case, the energy of compressed air, and not water, is converted into mechanical energy. Both hydraulic and pneumatic systems quite effectively cope with their task.
The advantage of devices of the second variety is, first of all, the lack of the need to return the working fluid back to the compressor. The advantage of hydraulic systems in comparison with pneumatic systems is that the medium in them does not overheat and does not overcool, and therefore, no additional nodes and parts need to be included in the circuit.