The installation of hydraulic system, including the installation of hydraulic pipelines, hydraulic components, auxiliary components, etc., is to connect the various units or components of the system to form a circuit through fluid connectors (a general term for oil pipes and joints) or hydraulic manifolds. This article shares the installation requirements and precautions of hydraulic pipelines, hydraulic components, and auxiliary components in hydraulic systems.

According to the connection form of hydraulic control components, they can be divided into integrated type (hydraulic station type) and distributed type. Both types need to be connected through fluid connectors.

1. Installation of pipe connectors

(1) Installation and requirements of oil suction pipe

① The oil suction pipe should be as short as possible, with few bends and appropriate pipe diameter. It should not be too thin.

② The oil suction pipe should be tightly connected and should not leak, so as to prevent the pump from sucking in air during operation, causing noise in the system and making it impossible to suck oil. Therefore, it is recommended to use sealant to connect the oil suction pipe at the pump suction port.

③ Except for plunger pumps, filters should be installed on the oil suction pipe of hydraulic pumps. The oil filtration accuracy is usually 100-200 mesh. The flow capacity of the filter is at least twice the rated flow of the pump. At the same time, it is necessary to consider the convenience of disassembly and assembly during cleaning. Generally, in the design process of the oil tank, a hand hole is opened near the oil suction filter of the hydraulic pump based on this consideration.

(2) Installation and requirements of oil return pipe

① The main oil return pipe of the actuator and the oil return pipe of the overflow valve should extend below the oil tank liquid level to prevent oil from splashing and forming bubbles. At the same time, in order to further improve the efficiency and safety of the system, the oil return pipe should be cut into a 45° bevel facing the oil tank wall.

② When the oil drain port of the pressure reducing valve, sequence valve, solenoid valve, etc. with external leakage is connected to the oil return pipe, no back pressure is allowed. Otherwise, the oil drain port should be connected back to the oil tank separately to avoid affecting the normal operation of the valve.

③ The oil pipe installed in a horizontal plane should have a slope of 3/1000 to 5/1000. When the pipeline is too long, a pipe clamp for clamping the oil pipe should be fixed every 500mm.

(3) Installation and requirements of pressure oil pipes

The installation location of pressure oil pipes should be as close as possible to equipment and infrastructure, and it is also necessary to facilitate the connection and maintenance of branch pipes. To offset the vibration that may be generated by the pressure oil pipes, the pipelines should be installed in a solid position. Where vibration may occur, dampers should be added to eliminate vibration. In addition, wooden blocks or hard rubber pads can be installed on pipe clamps to prevent metal parts from directly contacting the pipelines, thereby further reducing vibration and noise.

(4) Installation and requirements of rubber hoses

① To protect the pipeline, sharp turns should be avoided. The bending radius R should be greater than 9 to 10 times the outer diameter of the pipe, and the bend should be made at least 6 times the diameter of the joint. When the hose is bent, the hose joint should be installed on the same motion plane to prevent twisting. At the same time, the connection should remain freely suspended to avoid unnecessary bending due to its own weight.

② The hose cannot work under tension and should have a certain margin (length change is about 4%). If the hose is too long or subjected to sharp vibration, it is advisable to clamp it with a pipe clamp, but hoses used under high pressure should use as few clamps as possible, because the hose will deform under pressure and friction energy loss will occur at the clamp.

③ Install the hose away from heat sources as much as possible, and install a heat insulation board or heat insulation sleeve when necessary. It must be ensured that the hose and the joint are compatible with the environmental conditions.

2. Installation of hydraulic components

Installation and specific requirements of various hydraulic components. Hydraulic components should be cleaned with kerosene during installation. All hydraulic components need to be tested for pressure and sealing performance. Installation can only begin after the test is qualified. To prevent potential accidents caused by accuracy problems, various automatic control instruments should be calibrated before installation.

The installation of hydraulic components mainly refers to the installation of hydraulic valves, hydraulic cylinders, hydraulic pumps and auxiliary components.

(1) installation and requirements of hydraulic valves

Before installing hydraulic components, check the certificate of conformity and review the instructions for the unpacked hydraulic components. If they are qualified products with complete procedures and are not products that have been rusted due to long-term outdoor storage, no additional tests are required, and re-cleaning is not recommended. They can be directly disassembled and assembled.

If a fault occurs during the test run, the components should be disassembled and assembled only when the judgment is accurate and necessary. Especially for foreign products, it is not allowed to be disassembled and assembled at will to avoid affecting the accuracy of the product when it leaves the factory.

When installing hydraulic valves, attention should be paid to the following:

①When installing, attention should be paid to the orientation of the oil inlet and return ports of each valve component.

②If the installation location is not specified, it should be installed in a location that is convenient for use and maintenance. Generally, the directional control valve should be installed with the axis level. When installing the reversing valve, it is necessary to tighten the four screws evenly, usually in groups in diagonal order.

③For valves installed with flanges, the screws should not be tightened too much, because excessive tightening sometimes causes poor sealing. When the original seals or materials cannot meet the sealing requirements, the form or material of the seals should be replaced.

④For the convenience of manufacturing and installation, some valves often have two holes with the same function. After installation, the unused one should be blocked.

⑤For valves that need to be adjusted, they are usually rotated in a clockwise direction to increase the flow and pressure; rotated in a counterclockwise direction to reduce the flow or pressure.

⑥When installing, if some valves and connectors are not available, it is allowed to use hydraulic valves with a flow rate exceeding 40% of their rated flow rate instead.

(2) Installation and requirements of hydraulic cylinders

The installation of the hydraulic cylinder must ensure that it is stable and reliable. All piping connections should be tightened and there should be no looseness. In addition, the mounting surface of the hydraulic cylinder and the sliding surface of the piston must maintain sufficient parallelism and verticality.

When installing hydraulic cylinders, pay attention to the following:

① For mobile cylinders with fixed feet, the central axis should be concentric with the axis of the load force to avoid lateral force, which can easily cause seal wear and piston damage. When installing hydraulic cylinders for moving objects, keep the cylinder and the moving object parallel in their movement direction on the guide surface.

② Install the sealing gland screws of the hydraulic cylinder body and tighten them to ensure that the piston floats over the full stroke to prevent the influence of thermal expansion.

3. Installation and requirements of hydraulic pumps

When the hydraulic pump is arranged on a separate oil tank, there are two installation methods: horizontal and vertical. In vertical installation, the pipelines and pumps are all inside the oil tank, which is convenient for collecting leaked oil and has a neat appearance. In horizontal installation, the pipelines are exposed outside, which is convenient for installation and maintenance.

Hydraulic pumps are generally not allowed to bear radial loads, so electric motors are often used to drive directly through elastic couplings. During installation, the motor and the shaft of the hydraulic pump should have a high concentricity, the deviation should be less than 0.1mm, and the inclination angle should not be greater than 1° to avoid adding additional loads to the pump shaft and causing noise.

In the case where belt or gear drive must be used, it should be ensured that the hydraulic pump does not bear radial and axial loads. The working principle of hydraulic motors is like that of pumps. Although some motors can tolerate a certain radial or axial load, the load should not exceed the allowable value specified by the manufacturer. For oil suction capacity, some pumps can withstand a higher oil suction height, while some pumps stipulate that the oil suction port must be below the oil level. For pumps without self-priming ability, auxiliary pumps are required for oil supply.

When installing a hydraulic pump, please note:

1) The inlet, outlet and rotation direction of the hydraulic pump should comply with the requirements marked on the pump and must not be reversed.

2) When installing the coupling, do not hit the pump shaft hard to avoid damaging the pump rotor.

4. Installation and requirements of auxiliary components

In addition to fluid connectors, the auxiliary components of the hydraulic system also include filters, accumulators, coolers and heaters, sealing devices, and pressure gauges and pressure gauge switches. Although these auxiliary components play an auxiliary role in the hydraulic system, their importance must not be ignored during the installation process. If improperly installed, it may seriously affect the normal operation of the hydraulic system.

Attention should be paid to the installation of auxiliary components:

1) The installation should strictly follow the position specified in the design, and attention should be paid to neatness and aesthetics.

2) Before installation, kerosene should be used for cleaning and inspection.

3) While complying with the design regulations, the convenience of use and maintenance of the equipment should be optimized as much as possible.