Oil Tank

Each piece of hydraulic equipment should have its own tank. The oil tank maintenance should be filled with oil, emit heat, escape air, settle impurities, separate water, and perform various functions, such as mounting components

(machine) filter

The function of the filter is to remove solid contaminants from the oil. Approximately 80 per cent of hydraulic system failures are caused by contaminated oil. Keeping the oil clean is the key to reliable operation of the hydraulic system, and the filter is the main means of keeping the oil clean.

Filter Type

Filters can be installed in different parts of the hydraulic system to perform different tasks, which determines the different types of filters:

A. Suction filter to protect hydraulic pumps

B. High-pressure filter protects downstream parts of the pump from contamination

C. Oil return filter to reduce oil contamination

D. Off-line filters, continuous filtration to maintain cleanliness

E. Oil drain filter to prevent contaminants from entering the tank

F. Safety filters to protect low contamination and low resistance parts

G. Ventilation filters to protect against airborne contaminants

G. Ventilation filters to protect against airborne contaminants

H. Oil filling filter to prevent the intrusion of contaminants during oil filling

Classification of hydraulic pumps

A. Quantitative pumps: gear pumps, screw pumps, quantitative vane pumps, quantitative radial piston pumps, quantitative axial piston pumps.

B. Variable pumps: variable vane pumps, variable radial piston pumps, variable axial piston pumps

C. Gear pumps: a pump that consists of two or more gears sealed in a casing to convey liquids by the change in volume of the workspace produced during mutual meshing.

In its most basic form, a hydraulic pump engages and rotates two gears of the same size in a closely matched housing. The inside of the casing has a shape similar to an ‘8,’ with two gears mounted inside. The outer diameter and sides of the gears closely match the casing. Hydraulic fluid enters between the two gears through the suction port and fills the space. As the teeth rotate, they move along the housing and discharge when the two teeth finally mesh.

Since the liquid cannot be compressed, the liquid and the teeth cannot occupy the same space at the same time and therefore the liquid is excluded. This phenomenon occurs continuously due to the continuous engagement of the teeth, thus providing a continuous discharge volume at the pump outlet. Each time the pump rotates, the discharge volume is the same. With the uninterrupted rotation of the drive shaft, the pump discharges fluid uninterruptedly.

hydraulic motor

High-speed hydraulic motor:

A. Quantitative hydraulic motors (gear motors, screw motors, quantitative vane motors, quantitative radial piston motors, quantitative axial piston motors)

B. Variable hydraulic motors (variable radial piston motors, variable axial piston motors)

2. Low-speed hydraulic motor:

A. Single-action hydraulic motors (radial piston hydraulic motors)

B. Multifunctional hydraulic motors (radial piston hydraulic motors, vane motors, cycloidal motors)

hydraulic cylinder

The role of the hydraulic cylinder: the hydraulic energy is converted into mechanical energy actuator.

The input to a hydraulic cylinder is the flow and pressure of the fluid, and the output is the speed and force of the linear motion. The piston of the hydraulic cylinder completes linear reciprocating motion, but its linear displacement output is limited. Hydraulic cylinders basically consist of a cylinder and cylinder head, a piston and rod seal, a cushioning device and an exhaust device. Cushioning device and exhaust device depends on the specific application, other devices side is essential.

Hydraulic cylinders are used in a wide range of applications, they are the main actuator for inheriting loads and can utilise a small space to obtain a large force, they have been widely used in various industries.

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Pressure control valves

Pressure control valves can be divided into: safety valves, solenoid relief valves, overflow valves, sequence valves, unloading valves, counterbalance valves, backpressure valves, pressure reducing valves, buffer valves, manual remote control valves, pressure relays, pressure gauge protection valves and so on.

The working principle of overflow valves: overflow valves mainly include direct-acting overflow valves and pilot operated overflow valves. As it is the basis of all kinds of overflow valves, we focus on the working principle of direct-acting overflow valves

In a direct-acting overflow valve, the force acting on the centre of the moving valve is in direct balance with the spring force. When the liquid pressure exceeds the pre-adjusted spring force, the valve’s center opens, allowing pressurized oil to overflow and maintain stable inlet pressure. When the pressure decreases, the spring force closes the valve. Direct-acting overflow valve structure is simple, high sensitivity, but the static pressure regulation deviation (the difference between the regulation pressure and the opening pressure) is large, the dynamic characteristics of the cone and other structural forms, the ball valve response is fast, sensitive action, but poor stability, noise. People usually use it as a pilot valve for safety and pressure valves. Slide valve overflow valve slow response, overpressure, but good stability.

The main function of the overflow valve is to keep the pressure of the oil circuit system constant, to prevent the system from overloading, to protect the pump and the oil circuit system safety.

The main performance requirements of overflow valve are: large pressure regulation range, small pressure regulation deviation, small pressure swing, sensitive action, large overflow capacity, small pressure loss, good noise characteristics.

Flow control valves

A flow control valve is a valve that regulates the speed of movement of an actuator (hydraulic cylinder or hydraulic motor) by controlling the flow rate through a throttle port at a certain differential pressure.

Install throttle valves, including speed control valves, relief throttle valves, and shunt collector valves, horizontally.

Throttle valve: Throttle valve is a kind of control system by changing the throttle speed control system, i.e. inlet throttle speed control system, loop throttle speed control system and bypass throttle speed control system. Throttle valve has no negative flow feedback function, can not make up for the speed instability caused by load change. Use it primarily in cases of small load changes or low-speed stability requirements.

Directional control valves primarily open the oil circuit or change the direction of oil flow to control the start and stop of the actuating element, as well as adjust pressure and speed. Directional valves can be classified into check valves and directional valves according to their use.

Check Valve: Only allows oil to flow in one direction, not the reverse.

Directional Valve: A directional valve is a control valve that can change the direction of hydraulic oil flow in a hydraulic system. By changing the position between the spool and the valve body to change the direction of oil flow.