Hydraulic Parts

What are the hydraulic parts？

Hydraulic systems are widely used as general equipment in industry, which increase force by changing pressure. In terms of composition, the hydraulic system consists of two parts: hydraulic accessories and working medium. Hydraulic accessories can be further divided into four parts: power components, execution components, control components and auxiliary components.

1 Power Hydraulic Accessories
Power components refer to various hydraulic pumps and their prime movers, which are used to convert the mechanical energy provided by the prime mover (electric motor or internal combustion engine) into pressure energy of the fluid and output oil with a certain pressure.

1) There are two structural types of gear oil pumps and double-chamber pumps (including external meshing and internal meshing).
2) Vane oil pumps (including single-stage pumps, variable displacement pumps, double-stage pumps and duplex pumps).
3) The plunger oil pump is divided into an axial piston oil pump and a radial piston oil pump. The axial piston pump has a fixed displacement pump and a variable displacement pump (variable displacement pumps are also divided into manual variables, pressure compensation variables, servo variables, etc.). They are structurally divided into two oil distribution methods: end face Oil distribution and valve oil distribution. The oil distribution method of radial piston pump is basically valve oil distribution.

2Control hydraulic accessories
Control hydraulic accessories mainly refer to various pressure, flow, direction control valves and their control hydraulic accessories. They are used to control the liquid pressure, flow and direction from the power source to the actuated hydraulic accessories in the regulation system, thereby controlling the output of the actuated hydraulic accessories. The force, speed and direction to ensure that the host working mechanism driven by the actuated hydraulic accessories completes the predetermined movement pattern.

1) Pressure valve
(1) Pressure control valves include: relief valves, electromagnetic relief valves, unloading relief valves, one-way relief valves and pressure reducing valves, one-way pressure reducing valves, sequence valves and one-way sequence valves.
(2) Sequence valves are divided into seven types: direct control sequence valve, remote control sequence valve, unloading valve, direct control one-way sequence valve, remote control one-way sequence valve, direct control balancing valve and remote control balancing valve, and pressure Relays and various pressure control valves. They are used in various hydraulic transmission systems according to different usage conditions and characteristics.
2) Directional control valve
Directional control valves include check valves, hydraulic control check valves, electromagnetic reversing valves, solenoid ball valves, electromagnetic reversing valves, manual reversing valves and manual rotary valves.
3) Flow control valve
Flow control valves include throttle valves, one-way throttle valves, speed regulating valves, one-way speed regulating valves, stroke throttle valves, stroke one-way throttle valves and stroke one-way speed regulating valves, etc.

Installation Tips for Hydraulic Accessories

The performance level of the connecting screws used for valves in hydraulic accessories must comply with the manufacturer's requirements and must not be replaced at will. Coupling screws should be tightened evenly (do not hit with a hammer or pull hard) and should not be unscrewed out of alignment. The mounting plane of the valve should be in complete contact with the mounting plane of the base plate or oil manifold block. (2) Pay attention to the direction of the oil inlet and return port. If some valves are installed improperly, accidents may occur. For ease of installation, some valves usually have two holes with the same function, and the unused holes should be blocked after installation. (3) The installation method of hydraulic valves should comply with the regulations of the manufacturer and system design drawings. (4) Flat valves or cartridge valves must have correct orientation measures. (5) In order to ensure safety, the effects of gravity, impact and vibration on the main components of the valve must be considered when installing the valve. (6) Under normal circumstances, the directional valve should be installed so that the axis is horizontal; (7) For valves that generally need to be adjusted (such as flow valves, pressure valves, etc.), the flow and pressure will increase when rotating clockwise, and when rotating counterclockwise Flow and pressure will be reduced.

1. Hydraulic fittings pipeline: (1) Oil pipes should be selected according to pressure and application conditions. The oil pipe must have sufficient strength. The inner wall should be smooth, clean, and free of sand, rust, and scale. For pipes stored for a long time, they should be pickled, cleaned, cleaned and inspected before processing. (2) When cutting pipes with a saw, the non-perpendicularity between the cross-section and the axis direction should be ±0.5°, the sharp edges should be rounded and iron filings removed. When processing bent pipes, the cross-sectional ovality is allowed to be 10%. When the outer diameter is less than 14mm, the pipe can be bent by hand and general tools. Thicker steel pipes should be bent using a manual or electric pipe bender, and the bending radius should generally be greater than 3 times the outer diameter of the pipe. (3) The requirements for installing pipelines are that the pipelines should be short and have as few turns as possible. The pipelines should be equipped with exhaust devices to facilitate deflation during startup. (4) When installing rubber hoses, avoid sharp turns. The bending radius R ≥ (9~l0) D (D is the outer diameter of the hose). Do not bend near the root of the connector, the distance L ≥ 6D from the hose connector to the start of the bend. The hose must not be twisted during operation. (5) The oil suction pipe must not leak or have excessive resistance to prevent difficulty in suction or cavitation during oil suction. (6) The oil return pipe hole must extend below the oil level in the fuel tank to prevent splashing and air bubbles. The return pipe of the relief valve cannot be directly connected to the inlet of the pump. It must pass through the fuel tank, otherwise the oil temperature will be too high. (7) The installation procedure of all pipelines should be carried out in two steps. Trial assembly should be carried out first, and pipe joints and flanges should be spot welded at appropriate locations. After all pipes have passed trial assembly, they should be removed and pickled before formal installation.

2. Other hydraulic accessories: (1) All hydraulic accessories should undergo pressure and sealing tests and can be installed only after passing the test. Before installation, various automatic control instruments should be calibrated to avoid errors. (2) When installing various control valves, pay attention to the directions of their oil inlets and return ports. When installing flanged valves, do not overtighten the screws, otherwise a poor seal may result. (3) The hydraulic cylinder is installed firmly and reliably. To prevent the effects of thermal expansion, one end of the cylinder must remain floating when the stroke is large and the temperature is high. The sealing ring of the hydraulic cylinder should not be too tight, especially the U-shaped ring, to avoid excessive resistance. (4) The different axial deviations between the hydraulic pump drive shaft and the motor drive shaft should be less than 0. Flexible couplings are usually used for connection. It is not allowed to use tape to directly drive the pump shaft to rotate to prevent the pump shaft from being subjected to excessive radial force and affecting the normal operation of the pump. (5) When installing the hydraulic pump, its rotation direction and oil inlet and outlet should meet the technical requirements.