Installing filters in the hydraulic system. Hydraulic tank filter

KENTEK company on favorable conditions offers a wide selection of hydraulic filters for special equipment. The catalog includes popular consumables for machines of both Asian and European brands, including: DOOSAN DAEWOO, Caterpillar, KOMATSU, MANITOU, HITACHI and others. All products sold are of enviable quality and attractive price.

Hydraulic filters for special equipment: features

Filters for hydraulics for excavators and other special equipment are characterized by high dirt capacity and efficiency, which is the result of the most rational use of the internal space of products. High-strength cases are completely tight, which provides high reliability and durability.

The main feature of hydraulic filters for special equipment is that these compact devices are designed to operate in conditions of sharp pressure drops and intensive changes in the direction of flow of the working medium.

KENTEK special equipment hydraulic filters: benefits of collaboration

• Professional support . Before purchasing hydraulic filters for loaders or excavators, customers can consult our technical experts, who will quickly select the necessary components for a particular model. If necessary, we will offer a certified alternative if the previously operated name is discontinued.
• Big choice . We offer hydraulic filters for excavators and loaders of all brands that are represented in the CIS regardless of the model and date of manufacture or country of assembly.
• Attractive prices . KENTEK is a direct distributor of tradable brands that allows you to create the most attractive sales conditions. It is possible to order hydraulic filters for special equipment from us in bulk with payment by bank transfer. There are special conditions for dealers.
• Guarantees . Each item is sold with a manufacturer’s warranty and undergoes a thorough check both when it arrives at the warehouse and before it is sent to the client, which minimizes the likelihood of a defective item being delivered.

Buy inexpensive filter hydraulic excavator in St. Petersburg

In order to purchase hydraulic filters for excavators on favorable conditions, it is enough to call KENTEK managers in St. Petersburg and inform the numbers of the used components. Using an individual approach, for each client we will provide the best conditions for cooperation without sacrificing the quality of products or services.

The selection of the filter and its proper installation in the hydraulic system should be made as carefully as the selection of the remaining elements of the hydraulic drive.

When choosing the installation scheme, it is necessary to take into account many factors: the source of pollution; sensitivity of hydraulic drive elements to pollution; machine operation mode; operating pressure; regularity and irregularity of service; type of working fluid; Operating conditions.

Installation is possible on the suction, pressure and drain lines (Fig. 5.7), as well as in the branches.

Installation of filters on the suction hydraulic line F4  provides protection of all elements of a hydraulic system.

Disadvantages: the suction capacity of the pumps will deteriorate and cavitation may occur. Additionally, an indicator is installed that turns off the pump drive together with a non-return valve, which switches on when unacceptable clogging occurs. The pressure drop on them should not be large. Fine filtering is not possible.

Installation of filters in the pressure head hydraulic line F5  provides protection for all elements except the pump. Clogging can cause destruction of the filter elements. For this, safety valves are installed.

Disadvantages: Costly filter housing and filter element since high strength is required. We have to stop the system to change the filter element.

Installation of filters on the drain hydraulic line F1  the most common, since the filters do not experience high pressure, do not create additional resistance on the suction and pressure lines and retain all mechanical impurities contained in the working fluid returning to the hydraulic tank.

Disadvantages: It is required to install safety valves in the filter and stop the system to change the filter element. It does not protect highly sensitive elements, creates a backwater in the drain hydroline.

Fig.5.7.  - Filter switching schemes: a  - on the soaking-up hydroline; b  - in pressure head hydroline; in - in a drain hydroline

Filters jellied F2  (filler neck). Clean the working fluid again poured into the hydraulic tank.

Installation in a bypass (bypass) line F6. The task of these filters is to clean the working fluid in the hydraulic tank during its circulation. In most cases, filter systems are used, consisting of a pump and a filter, or a pump, a filter and an oil cooler.

Advantages: uniform filtration independent of the work process, cheap filter housing and filter element. When changing the filter element, the system does not stop.

Disadvantages: Does not protect highly sensitive elements, increased energy consumption by the system due to the use of an additional pump. Increased investment in the purchase of a filter system.

Filters in the bypass line should be provided in case severe pollution from the environment is expected (test benches, installations operating in conditions of significant dustiness).

Air filter  (breather) F3. The task of these filters is to clean the air entering the hydraulic tank when the volume of oil in the tank changes during operation.

07.09.2012

The main function of hydraulic filters is to protect the hydraulic system and protect its components from wear. Filters ensure that the main components of the hydraulic system are maintained. Hydraulic filters are used in hydraulic systems and transmissions of earthmoving, loading, forestry machines, in road-building machinery, in equipment of chemical, concrete, asphalt plants, drilling rigs, as well as in agricultural machinery. Hydraulic filters ensure the safety of systems when operating under extreme pressures. That is why high-quality hydraulic filters and their components are an opportunity to maintain the operability of hydraulic systems and transmissions, thereby saving the owner of the equipment.

Most of the defects that appear in hydraulic systems are associated with pollution. Thus, insufficient hydraulic fluid filtration is 80% of system defects. Contaminants are formed in the liquid as a result of mechanical wear of the parts. During friction, the parts form metal chips that enter the hydraulic fluid. In addition to it, emulsified or free water can act as a pollutant. Various types of pollutants can also enter the system from the air.

Also, pollution is initially found in new oil - water, silicon, fibers, various metals. And during operation, additional contaminants enter the liquid from the breather filter and the seals of the working hydraulic cylinders. Therefore, to ensure high-quality and reliable operation of the equipment, the use of filters is a prerequisite.

Each filter has an important criterion - filtering efficiency. It is calculated based on the number of pollutants before and after it. Moreover, as the filter is used and clogged during operation, the coefficient changes. Therefore, it is necessary to carefully monitor the condition of the filters and change them as necessary.

Differences of hydraulic filters from oil and fuel

The main differences between hydraulic filters and fuel and oil analogues are as follows:

• Hydraulic filters have a high working pressure - up to 450 bar.
• Hydraulic filters have a large pressure drop.
• Able to withstand greater fluid flow - over 500 liters per minute.
• Other types of filter materials are used as cleaning, barrier elements.

As a rule, several filters are installed in hydraulic systems. Each of them performs its own special functions:

• In the tank - coarse filters. For their manufacture, metal fiber from 90 mµ to 120 mµ is used. These filters can be equipped with a safety mechanism.
• Suction filters. They can be installed directly in or on the hydraulic tank itself. 20 micron fiberglass or cellulose suction filters are produced. Additionally equipped with a thin mesh network, trapping particles with a diameter of 25 to 60 microns.
• Pressure filters. They are installed in the working system between the pump and the component that must be protected from contamination. These filters are able to withstand high pressures - 430 bar.
• Drain filters. They are installed in a drainage water supply that fits the tank. These types of filters are mounted in those systems in which it is not possible to install pressure and suction filters, as well as in equipment that use hydraulic cylinders.
• Breather filter. Installed on the tank. Its function is to prevent air pollution from entering the tank.
• Additional filters. They are used in systems containing a large volume of oil, as well as when connecting multiple hydraulic systems to one tank. These filters control and maintain the required level of cleanliness in the system.

In addition to the main types of filters, the use of additional cleaning devices is possible. One of them is a mobile system. Its function is to clean the working hydraulic fluid. The main advantage of such systems is that they work simultaneously with the system - there is no need to stop the workflow to start them. Mobile hydraulic fluid cleaning systems are able to remove air, foreign particles and partially oil pollution from the working medium. The cleaning process occurs by recirculating the liquid in the tank.

Filters are used to clean the working fluid from impurities contained in it. These impurities consist of foreign particles entering the hydraulic system from the outside (through gaps in the seals, when filling and adding working fluid to the hydraulic tank, etc.), from the wear products of the hydraulic unit and the products of oxidation of the working fluid.

Mechanical impurities cause abrasive wear and lead to jamming of moving pairs, worsen the lubrication of the friction parts of the hydraulic drive, reduce the chemical resistance of the working fluid, clog narrow channels in the control hydraulic equipment.

Impurities are delayed by filters (Fig. 3), the principle of operation of which is based on the passage of fluid through filtering elements (slotted, mesh, porous) or through force fields (separators). In the first case, impurities are trapped on the surface or in the depth of the filter elements, in the second, the working fluid passes through an artificially created magnetic, electric, centrifugal or gravitational field, where impurities settle.

Figure 6. Fluid Filtration Scheme

By the fineness of cleaning, i.e. according to the size of the detained particles, the filters are divided into coarse, normal and fine filters.

Coarse filters retain particles up to 0.1 mm in size (mesh, plate) and are installed in the holes for filling the working fluid in hydraulic tanks, in suction and pressure hydraulic lines and are used for preliminary cleaning.

Filters of normal cleaning retain particles from 0.1 to 0.05 mm (mesh, plate, magnetically mesh) and are installed on pressure and drain hydraulic lines.

Fine filters retain particles less than 0.05 mm in size (cardboard, felt, ceramic), are designed for low flow rates and are installed in branches from hydraulic lines.

Depending on the installation locations of the filters in the hydraulic system, high filters and low pressure filters are distinguished. The latter can only be installed on suction or drain lines.

\u003e Filter designs

Strainers are installed on the suction and drain lines, as well as in the filling openings of the hydraulic tanks. The filter element is a brass mesh, the mesh size of which determines the fineness of cleaning the working fluid. The mesh is set in one or more layers. To reduce the resistance, the filter surface is made as large as possible.

Figure 7: Strainer

1 - case; 2 - mesh; 3 - disks; 4 - perforated tube; 5 - a nut; 6 - gaskets.

Fig. 4. The design of the strainer is shown. The filter consists of a housing 1 with openings for passing the working fluid and covered with two layers of mesh 2. The end surfaces of the filter are closed by two disks 3. A steel perforated pipe 4 passes through the central openings of the disks and is connected to the suction pipe of the pump unit.

Wire filters have a similar design. They consist of a pipe with a large number of radial holes or grooves, on the outer surface, which is wound round a calibration wire of circular or trapezoidal cross-section. The gap between the rows of wires determines the fineness of the filtration of the working fluid (up to 0.05 mm). The drawback of mesh and wire filters is the difficulty in cleaning the filter elements from contaminants accumulated on their surface.

Plate (slotted) filters are installed on pressure and drain hydraulic lines of hydraulic systems. The plate filter type G41 (Fig. 5) consists of a housing 1, a cover 2 and an axis 3, on which a packet of filtering elements is fixed. A cover having holes for supplying and discharging liquid is bolted to the housing, and the joint between them is sealed with a rubber ring 4. The package of filter elements consists of a set of main 5 and intermediate plates 6. The fluid enters the filter housing and through the slots between the main and intermediate plates enters the internal cavity of the filter formed by cutouts in the main plates. When fluid flows through slots, the mechanical impurities contained in it are delayed. The fineness of cleaning depends on the thickness of the intermediate plates. Slots become clogged during filter operation. For cleaning, scrapers 7, mounted on the hairpin 8, are used. When the handle 3 is rotated by the handle, the scrapers placed between the main and intermediate plates clean the dirt layer at the entrance to the slots. When dirt is accumulated at the bottom of the housing, they are removed through an opening in the lower part of the housing 9. Such a relatively simple cleaning method is the advantage of plate filters.

Picture. 8. Plate filter type G41:

1 - case; 2 - cover; 3 - axis; 4 - rubber ring; 5 - main plates; 6 - intermediate plates; 7 - scrapers; 8 - hairpin; 9 - cork.

G41 plate filters are produced at a flow rate of up to 70 l / min with a pressure drop of 0.1 and 0.2 MPa. Depending on the size of the filters, the smallest size of the retained particles is 0.08, 0.12 and 0.2 mm.

Mesh, wire and slot filters have little resistance when the working fluid flows through them, but the subtlety of their cleaning is small.

To improve the cleaning of the working fluid, fine filters are used, which have high resistance and are designed for low costs. They are installed on branches from hydraulic lines. In order to avoid quick clogging, coarse filters are installed in front of the fine filters.

Fine filters use fabric, cardboard, felt and ceramic filter elements.

Filters with cardboard and fabric elements delay in a single pass a significant (up to 75%) portion of solids larger than 4-5 microns. A diagram of such a filter with a combined element consisting of fine 2 and coarse 1 elements is shown in Figure 8.1. Before opening the bypass valve 3, the liquid passes through both elements in series (Figure 8, a). If the fine-filter element becomes clogged, the bypass valve 3 opens, and the liquid flows through the coarse element to the outlet fitting, bypassing the fine-element (Figure 8, b).

Figure 9. The combined filter from elements of rough and fine cleaning

The paper element is usually made in the form of a cylinder, the walls of which are collected in folds of one form or another to increase the filtering surface (Figure 9).

Felt and cermet filters are fine filters. They are also called deep, since the fluid passes through the thickness of the porous material (filler). They have a higher dirt capacity and a relatively long service life.

Figure 10. Figure 10.1.

Paper filter element Structure of the filter material of sintered balls

Depth-type filters with fillers of porous metals and ceramics obtained by sintering metal and nonmetallic powders are widespread. The porous structure of the cermet filter material is shown in Fig. 8. The fluid is cleaned by flowing along long and winding channels between the balls.

Felt filters (Fig. 9) consist of a housing 1, a cover 2 with holes for supplying and discharging a working fluid, a perforated pipe 3 with filtering elements fixed in it in the form of felt rings 4.

Separators have unlimited throughput with low resistance. The principle of their operation is based on the passage of the working fluid through the force fields that trap impurities. As an example, Fig. 10 shows the design of the magnetic filter C43-3, designed to capture ferromagnetic impurities. The filter consists of a housing 3, a cover 8 with a brass pipe 7 screwed into it, and a magnetic trap. The trap includes a round washer 4 with six holes in which the permanent magnets are pressed 9. The magnets are insulated from the filter cover with a fiber spacer 5. A brass washer 2 is mounted at the bottom of the pipe to shield the magnetic field created by the permanent magnets and prevent its closure to the housing filter.

Figure 11. Felt filter G43 Figure 11.1. Magnetic filter C43-3 1-body; 2-cover; 1-stopper; 2-brass washer; 3-

3-perforated pipe; 4-filter housing; 4-washer; 5-gasket; items 6-seal; 7 brass pipe; 8-cap; 9-magnets.

Installing filters in the hydraulic system

When choosing an installation scheme, many factors must be considered:

Source of pollution;

Sensitivity of hydraulic drive elements to pollution;

Machine operating mode;

Operating pressure;

Regularity and irregularity of service;

Type of working fluid;

Terms of Use.

Installation is possible on the suction, pressure and drain lines (Fig. 7.11), as well as in the branches.

Figure 12. Filter switching schemes:

a - on the suction line; b - in a pressure head hydraulic line; in - in a drain hydroline

Installing filters on the suction line protects all elements of the hydraulic system. Disadvantages: the suction capacity of the pumps will deteriorate and cavitation may occur. Additionally, an indicator is installed that turns off the pump drive together with a non-return valve, which switches on when unacceptable clogging occurs (Figure 12, a).

Installing filters in the pressure hydraulic line protects all components except the pump. Clogging can cause destruction of the filter elements. For this, safety valves are installed (Figure 12, b).

Installing filters on the drain hydraulic line is the most common, since the filters do not experience high pressure, do not create additional resistance on the suction and pressure lines and retain all mechanical impurities contained in the working fluid returning to the hydraulic tank. The disadvantage of this scheme is to create a backwater in the drain hydroline, which is not always desirable.

Hydraulic tank filter  It is intended for cleaning the working fluid from foreign metal impurities remaining in the aggregates and pipelines after assembly, from impurities formed as a result of wear of parts, and from impurities entering the hydraulic system when filling the fluid, as well as during operation - through the tank breather and the gaps between front cover and ram cylinder.

In the hydraulic systems of tractors, agricultural, construction and road machines, metal grids, wire plate parts and with spiral winding are used.

Filters from porous metal obtained by the method of sintering spherical and droplet-like particles, and cermet filters are now being used.

In tractor separate aggregate hydraulic systems, mesh filters are used, which are installed at the end of the drain pipe in the tank. Therefore, they are called drain filters.

Hydraulic Drain Filter

Hydraulic Drain Filter  consists of a stamped housing 12, a lower cover or neck 6, a filter section and a cover 5. The filter section consists of a perforated tube 15, on which a packet of filter elements 13, a ball bypass valve assembly and a reflector 1 are assembled. The bypass valve is assembled on the tube 15. Its details are a cup 9, a spring 8, a ball 7 and a valve body 3. The bypass valve is used to transfer fluid to the hydraulic tank in case of clogging of the filter elements. The opening pressure of the bypass valve in the tractor hydraulic systems is from 0.2 to 0.35 MPa (from 2 to 3.5 kgf / cm2). A reflector 1 is installed on the valve body, which presses the filter section to the filter body. The reflector has a shape that allows it to spring, so it extinguishes strong jets of liquid and protects the mesh elements from its sharp impacts.

Fig. Diagram of the drain filter of the tractor hydraulic system:
  1 - reflector; 2 - seal; 3 - body of the safety valve; 4 - a sealing ring; 5 - filter cover; 6 - a flange; 7 - safety valve; 8 - spring; 9 - a supporting glass; 10 - reflector washer; 11 - washer; 12 - filter housing; 13 - filter element; 14 - washer; 15 - filter pipe; 16 is a magnet.